TWI835580B - Multiple terminal end-to-end encryption communication method and computer readable medium - Google Patents

Abstract

The invention discloses a multiple terminal end-to-end encryption communication method and computer readable medium. A sending terminal generates a temporary key pair with a temporary public key and a temporary private key for a receiving account, and then calculates an account public key and the temporary private key to generate a ratchet key. Next, the sending terminal uses the ratchet key to derive a message key, and uses the message key to encrypt a message to generate a message ciphertext, and then uploads the message ciphertext and key information to a server. Thereafter, the server sends the message ciphertext and the key information to multiple receiving terminals. When the receiving terminal receives the message ciphertext, the receiving terminal uses the key information to generate the message key, and then uses the message key to decrypt the message from the message ciphertext.

Description

End-to-end encrypted communication method and computer-readable medium for multiple terminals

The present invention relates to a multi-terminal end-to-end encrypted communication technology (communication message encryption technology), and in particular to a multi-terminal end-to-end encrypted communication method and computer-readable medium.

Most of the current common multi-terminal end-to-end encrypted communication methods (such as instant messaging message encryption methods) can be divided into the following two types of technologies.

The first type of technology: the sending terminal conducts independent one-to-one encrypted communication with each receiving terminal. Since the messages between each terminal are independently encrypted, as the number of terminals grows, the calculations of the server and terminal will increase. volume and communication volume.

The second type of technology: the sending terminal randomly generates a set of keys, synchronizes this key to all receiving terminals through end-to-end encryption, and each terminal uses the key derivation function (KDF) to convert the key Derived into the message key used for encryption and decryption of subsequent messages. However, this second type of technology requires the key to be encrypted and then uploaded to the server, and the key synchronization will still be affected by the number of terminals.

Furthermore, the current mainstream instant messaging service providers use the above-mentioned first type of technology and the second type There are some methods proposed in the technology, but the number of terminals will still affect the performance. There is no solution that can combine performance, security and usability, and there is still a lot of room for improvement.

Therefore, how to provide an innovative multi-terminal end-to-end encrypted communication technology or communication message encryption technology to solve any of the above problems or provide related methods has become a major research topic for those skilled in the art.

The multi-terminal end-to-end encrypted communication method of the present invention includes: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal publicizes the account number of the receiving account. The key and the temporary private key of the temporary key pair are calculated to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the sending terminal The terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate the message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; and the server transmits the message The ciphertext and key information are sent to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, each receiving terminal uses the key information sent by the server to generate the corresponding ratchet gold The message key of the key allows each receiving terminal to use the message key corresponding to the ratchet key to decrypt the message from the message ciphertext.

The computer-readable medium of the present invention is used in a computing device or computer and stores instructions to execute the above-mentioned end-to-end encrypted communication method for multiple terminals.

Therefore, the present invention provides an innovative multi-terminal end-to-end encrypted communication method and computer-readable medium, which allows the user to use multiple terminals (such as a sending terminal/receiving terminal) at the same time. Multiple terminals send and receive message ciphertext (encrypted messages), and the communication between terminals Information can remain consistent. That is to say, the present invention can achieve message consistency between terminals, so that when a user uses any terminal to send or receive a message, the user's other terminals can automatically synchronize the message.

Furthermore, the present invention can use a ratchet key (ratchet method) to generate a message key to ensure forward security or forward secrecy (FS) of the message or message key. Or, when the terminal (such as the sending terminal) sends a message, the present invention can perform key exchange with the account public key of the receiving account, and then use the ratchet key to derive the message key to encrypt the message. It can be decrypted by multiple terminals of the receiving account, which is conducive to end-to-end encryption of the terminal account, and the number of message ciphertext sent by the terminal will not increase as the number of user terminals increases.

In addition, the present invention also discloses a multi-terminal end-to-end encrypted communication system including: a sending terminal, a receiving terminal and a server, wherein the sending terminal generates a temporary public key and a temporary private key for the receiving account. The temporary key pair is then used by the sending terminal to calculate the account public key of the receiving account and the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account. The ratchet key derives the message key, and then the sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal combines the message ciphertext with the gold Upload the key information to the server; and the server sends the message ciphertext and key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, each receiving terminal The key information sent by the server is used to generate a message key corresponding to the ratchet key, so that each receiving terminal can use the message key corresponding to the ratchet key to decrypt the message from the message ciphertext. In addition, the system implements the multi-terminal end-to-end encrypted communication method of the present invention to improve overall performance, security and usability.

In order to make the above-mentioned features and advantages of the present invention more clearly understandable, examples are given below. And provide detailed explanations with the attached drawings. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the scope of the invention.

a: first account

a1,a2: terminal

a3: New terminal

b:Second account

b1,b2: new terminal

c:server

P12 to P13: Program

P22 to P23: Program

P31, P34, P36 to P37: Program

P43,P45 to P47: Program

P61 to P63: Program

S11 to S14: Steps

S21 to S22: Steps

S31 to S38: Steps

S41 to S48: Steps

S51 to S59: Steps

Figure 1 is a schematic flowchart of adding a terminal in the end-to-end encrypted communication method for multiple terminals of the present invention.

FIG. 2 is a schematic flowchart of the initialization of an account key pair in the multi-terminal end-to-end encrypted communication method of the present invention.

FIG. 3 is a schematic flowchart of updating an account key pair in the multi-terminal end-to-end encrypted communication method of the present invention.

Figure 4 is a schematic diagram of the process of removing a terminal in the multi-terminal end-to-end encrypted communication method of the present invention.

FIG. 5 is a schematic flow chart of sending and receiving messages in the multi-terminal end-to-end encrypted communication method of the present invention.

FIG. 6 is a schematic diagram of the key derivation method in the multi-terminal end-to-end encrypted communication method of the present invention.

FIG. 7 is a schematic diagram of an embodiment of the newly added terminal shown in FIG. 1 in the multi-terminal end-to-end encrypted communication method of the present invention.

FIG. 8 is a schematic diagram of an embodiment of the initialization of the account key pair shown in FIG. 2 in the multi-terminal end-to-end encrypted communication method of the present invention.

FIG. 9 is a schematic diagram of an embodiment of updating the account key pair shown in FIG. 3 in the multi-terminal end-to-end encrypted communication method of the present invention.

FIG10 is a schematic diagram of an implementation example of removing the terminal shown in FIG4 in the end-to-end encrypted communication method of multiple terminals of the present invention.

FIG. 11 is a schematic diagram of an embodiment of sending and receiving messages shown in FIG. 5 in the multi-terminal end-to-end encrypted communication method of the present invention.

The embodiments of the present invention are described below through specific specific embodiments. Persons familiar with the art can understand other advantages and effects of the present invention from the content disclosed in this specification, and can also implement it through other different specific equivalent embodiments or Use.

Figures 1 to 5 are respectively flow diagrams of adding a terminal, initializing the account key pair, updating the account key pair, removing the terminal, and sending and receiving messages in the multi-terminal end-to-end encrypted communication method of the present invention.

In one embodiment, "at least one" in the present invention represents more than one (such as one, two or more than three), and "plurality" represents more than two (such as two, three, four, five or more than ten). "Terminal" can be a communication terminal, electronic terminal, user device, smart phone, tablet computer, personal computer, notebook computer, desktop computer, etc. "New terminal" can be a new or newly added terminal, " "Old terminal" can be an old or original terminal. "Message" can be a communication message or instant messaging message, etc. "Message ciphertext" can be an encrypted message, etc. "Send message" means sending a message, and "receive" means receiving a message. However, the present invention is not limited to what is mentioned in each embodiment.

The multi-terminal end-to-end encrypted communication method of the present invention is also called a multi-terminal end-to-end instant messaging encryption method or an instant messaging message encryption method, and can be divided into the following three embodiments: [1] adding a new terminal, [2] removing a terminal, and [3] sending and receiving messages.

[1] Add terminal: As shown in Figure 1, the process of "adding terminal" may include the following steps S11 to step S14. That is, when the user adds at least one (eg, multiple) new terminals, the new terminal can upload the public key (eg, terminal public key) to the server, and then add or update the account key pair later.

Step S11: The new terminal generates a public and private key pair through Elliptic Curve Cryptography (ECC). In order to avoid confusion in subsequent explanations, this public and private key pair is named a terminal key pair, and this terminal key pair can Has the terminal public key and terminal private key.

Step S12: The new terminal uploads the terminal public key of the terminal key pair to the server.

Step S13: The server returns the valid terminal information list under the user's current account to the new terminal.

Step S14: The new terminal determines that the account key pair should be initialized or updated based on the valid terminal information list. For example, if the effective terminal information list only records information about new terminals (that is, newly added terminals), the new terminal will initialize its account key pair (see Figure 2); conversely, if the effective terminal information list does not only record information about new terminals (that is, the newly added terminal) information also records the information of other terminals (old terminals), then the new terminal updates the account key pair (see Figure 3).

[1-1] As shown in Figure 2, the process of "initialization of account key pair" may include the following steps S21 to step S22.

Step S21: The new terminal generates a public-private key pair through elliptic curve cryptography (ECC). This public and private key pair can be named an account key pair, and the account key pair can have an account public key and an account private key.

Step S22: The new terminal uploads the account public key of the account key pair to the server for storage. This completes the initialization of the account key pair. Then, the server can respond to the new terminal with a unique account public key identification code ID based on the account public key of the account key pair.

[1-2] As shown in Figure 3, the process of "updating the account key pair" may include the following steps S31 to step S38.

Step S31: The new terminal obtains the current account private key from the old terminal through a method other than the server. For example, non-server methods may include: displaying the current account private key on the screen of the old terminal in hexadecimal (HEX), text (such as numbers/characters/special symbols) or quick response code (QR code), etc. , and then the new terminal obtains the current account private key from the screen of the old terminal through this hexadecimal (HEX), text or quick response code (QR code).

Step S32: The new terminal generates the first update parameter. For example, the first update parameter may be a number (such as a positive integer).

Step S33: The new terminal uses the current account private key and the first update parameter to generate a first new account key pair having a first new account public key and a first new account private key.

Step S34: The new terminal generates a public-private key pair through elliptic curve cryptography (ECC). This public-private key pair may be called a first temporary key pair, and the first temporary key pair may have a first temporary public key and a first temporary private key.

Step S35: The new terminal sequentially uses the terminal public keys of multiple (all) old terminals and the first temporary private key of the first temporary key pair to encrypt the first update parameter.

Step S36: The new terminal uploads the first new account public key, the first temporary public key and the encrypted first update parameter to the server.

Step S37: The server synchronizes the encrypted first update parameters to multiple (all) old terminals.

Step S38: Multiple (all) old terminals update their account key pairs.

[2] Removing the terminal: As shown in Figure 4, the process of "removing the terminal" may include the following steps S41 to step S48. That is, when the user removes another terminal by operating the terminal, the account key pair needs to be updated, and then the update information of the account key pair is synchronized to other terminals.

Step S41: The operation terminal generates the second update parameter. For example, the second update parameter may be a number (such as a positive integer).

Step S42: The operating terminal uses the current account private key and the second update parameter to generate a second new account key pair having a second new account public key and a second new account private key.

Step S43: The operating terminal generates a public-private key pair through elliptic curve cryptography (ECC). This public-private key pair may be called a second temporary key pair, and the second temporary key pair may have a second temporary public key and a second temporary private key.

Step S44: The operating terminal sequentially uses the terminal public key and the second temporary private key of the terminals other than the terminal to be removed to encrypt the second update parameter.

Step S45: The operating terminal uploads the second new account public key, the second temporary public key, the encrypted second update parameter and the terminal identification code ID of the terminal to be removed to the server.

Step S46: The server invalidates the terminal to be removed and notifies the terminal to be removed.

Step S47: The server synchronizes the encrypted second update parameter to other terminals except the terminal to be removed.

Step S48: Terminals other than the terminal to be removed update their own account key pairs.

[3] Sending and receiving messages: As shown in Figure 5, the process of "sending and receiving messages" may include the following steps S51 to step S59. That is, the sending terminal sends message ciphertext (added Encrypted message), the sending terminal and the receiving terminal generate corresponding message keys through a common ratchet key and a common derivation method to encrypt or decrypt the message.

Step S51: The sending terminal selects an account in the chat room that has not yet generated message ciphertext (encrypted message) as the receiving account.

Step S52: If the sending terminal has not generated a ratchet key for the receiving account, the sending terminal generates a third temporary key pair with a third temporary public key and a third temporary private key for the receiving account, and then the sending terminal generates a third temporary key pair for the receiving account. The messaging terminal operates the account public key of the receiving account and the third temporary private key of the sending terminal's third temporary key pair to generate a ratchet key (such as the Nth generation ratchet key) for the receiving account. N represents a positive integer, such as N=1,2,3….

Step S53: The sending terminal uses the ratchet key of the receiving account to derive the message key (such as the Nth generation message key), and updates the ratchet key (such as the Nth generation ratchet key) to the next generation ratchet key. (Such as the N+1 generation ratchet key).

Step S54: The sending terminal encrypts the message using the message key derived from the ratchet key of the receiving account to generate message ciphertext (encrypted message).

Step S55: Does the sending terminal check whether the message ciphertext (encrypted message) has been generated for multiple/all accounts in the chat room? If yes (message ciphertext has been generated for multiple/all accounts in the chat room), then continue to step S56; otherwise, if not (message ciphertext has not been generated for multiple/all accounts in the chat room), then return to the above. Step S51.

Step S56: The sending terminal uploads all message ciphertext (encrypted message) and key information to the server. For example, the key information may include the generation number of the ratchet key used (such as the Nth generation) and the account public key identification code ID when the ratchet key was derived. If the ratchet key is the first-generation ratchet key, then the key information A third temporary public key needs to be included (appended).

Step S57: The server checks the validity of the account public key of the receiving account. If the account public key is invalid, the server replies with the latest account public key to the sending terminal, so that the sending terminal regenerates the ratchet key and discards the message ciphertext (encrypted message); otherwise, if the account is public If the key is valid, continue to step S58.

Step S58: The server sends the message ciphertext (encrypted message) and key information to multiple (all) receiving terminals under the receiving account.

Step S59: When each receiving terminal receives the message (message ciphertext), if each receiving terminal checks that the message does not have a ratchet key for the sending terminal, each receiving terminal will combine the third temporary public key with the receiving terminal. The account private key of the message account is calculated to generate a ratchet key (such as the first generation or Nth generation ratchet key). Then, each receiving terminal uses the key information sent by the server to generate a message key corresponding to the algebra of the ratchet key (such as the first generation or Nth generation message key), and then each receiving terminal uses the corresponding ratchet key. The message key is the algebra of the key used to decrypt the message.

FIG. 6 is a schematic diagram of the key derivation method in the multi-terminal end-to-end encrypted communication method of the present invention. As shown in the figure, the sending terminal can calculate the account public key of the receiving account and the third temporary private key to generate a ratchet key (such as the first-generation ratchet key), and the receiving terminal will use the third temporary public key. The key is calculated with the account private key of the receiving account to generate a ratchet key (such as the first generation ratchet key).

In addition, the sending terminal can use the keyed-hash message authentication code (HMAC) and the first constant to derive the ratchet key into a message key (such as the first-generation message key) to send the message. The terminal uses a message key (such as a first-generation message key) to perform symmetric encryption of the message to generate message ciphertext (encrypted message). Similarly, the receiving terminal can also use the key hash message authentication code (HMAC) and the first constant to derive the ratchet key into a message key (such as the first-generation message key), and then the receiving terminal uses the message key (such as the first generation message key) convert the message ciphertext (plus encrypted message) to decrypt the message.

In order to ensure the security of the key, each time the message key is generated, the ratchet key will be updated to the next generation ratchet key, that is, the key hash message authentication code (HMAC) is used with the second constant to update the Nth generation ratchet key. The key is derived to the N+1 generation ratchet key (i.e., the next generation ratchet key). The aforementioned N represents a positive integer (such as N=1, 2, 3...), the first constant and the second constant can both be arbitrary values, and the first constant is different from the second constant.

As an example, the present invention uses the Elliptic Curve Diffie-Hellman key exchange (ECDH) protocol. To make the explanation easier to understand, assume that there is a first account a in a chat room. With the second account b, the first account a has valid terminal a1 and terminal a2, while the second account b does not have a valid terminal yet.

Message：代表訊息(如即時通訊訊息)，且訊息包括但不限於文字、圖片、音訊、影片或檔案格式等。

CT_Message^a1_b：代表終端a1所產生之訊息密文，且僅第二帳號b之終端可以解密。

(

,

)代表終端a1之終端公鑰、終端私鑰。

(

,

)：代表第一帳號a之帳號公鑰、帳號私鑰。

(

,

)：代表終端a1所產生之臨時公鑰、臨時私鑰。 The meanings of the symbols in this embodiment are explained below with examples.

Message: represents a message (such as an instant messaging message), and the message includes but is not limited to text, pictures, audio, video or file formats, etc.

CT_Message ^a1_b : represents the ciphertext of the message generated by terminal a1, and only the terminal with second account b can decrypt it.

(

,

) represents the terminal public key and terminal private key of terminal a1.

(

,

): represents the account public key and account private key of the first account a.

(

,

): represents the temporary public key and temporary private key generated by terminal a1.

ECDH(P,R)：代表透過橢圓曲線密碼學(ECC)之公鑰P與私鑰R進行橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定之運算結果。

G：代表橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定所使用之橢圓曲線之基點。

AES_encrypt(Key,Plaintext)：代表透過進階加密標準(Advanced Encryption Standard；AES)演算法(如AES256演算法)，將明文Plaintext(即未加密之訊息)使用金鑰Key進行加密以產生訊息密文Ciphertext。

AES_decrypt(Key, Ciphertext)：代表透過進階加密標準(AES)演算法(如AES256演算法)，將訊息密文Ciphertext使用金鑰Key進行解密以產生明文Plaintext(即已解密之訊息)。

HMAC(Key,Message)：代表使用金鑰Key將訊息Message進行金鑰雜湊訊息認證碼(HMAC)與安全雜湊演算法(Secure Hash Algorithm；SHA)之函數運算，且安全雜湊演算法可為安全雜湊演算法256位元(Secure Hash Algorithm 256-bit；SHA256)等。 also,

ECDH(P,R): represents the calculation result of the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol through the public key P and private key R of Elliptic Curve Cryptography (ECC).

G: represents the base point of the elliptic curve used by the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol.

AES _encrypt (Key, Plaintext): represents the use of the Advanced Encryption Standard (AES) algorithm (such as the AES256 algorithm) to encrypt the plaintext (ie, unencrypted message) using the golden key to generate a message encryption key. Ciphertext.

AES _decrypt (Key, Ciphertext): represents the use of the Advanced Encryption Standard (AES) algorithm (such as the AES256 algorithm) to decrypt the message Ciphertext using the key to generate the plaintext (i.e. the decrypted message).

HMAC (Key, Message): Represents the use of the key Key to perform function operations on the message Message between the key hash message authentication code (HMAC) and the secure hash algorithm (Secure Hash Algorithm; SHA), and the secure hash algorithm can be secure hash. Algorithm 256-bit (Secure Hash Algorithm 256-bit; SHA256), etc.

Figure 7 is a schematic diagram of an embodiment of the "new terminal" shown in Figure 1 in the multi-terminal end-to-end encrypted communication method of the present invention. As shown in Figure 7, when the scenario of adding a terminal is implemented, assuming that the first account a adds a new terminal a3, and the second account b adds a new terminal b1, then this embodiment may include the following procedures P11 to P14 the content.

與終端私鑰

之終端金鑰對，第二帳號b之新終端b1透過橢圓曲線密碼學(ECC)之方式產生一具有終端公鑰

與終端私鑰

之終端金鑰對，新終端a3保存自己之終端金鑰對之終端私鑰

，且新終端b1保存自己之終端金鑰對之終端私鑰

。 Procedure P11 (see step S11 in Figure 1): The new terminal a3 of the first account a and the new terminal b1 of the second account b each generate a terminal public key and a terminal private key through elliptic curve cryptography (ECC). Terminal key pair. For example, the new terminal a3 of the first account a generates a terminal public key through elliptic curve cryptography (ECC).

with terminal private key

For the terminal key pair, the new terminal b1 of the second account b generates a terminal public key through elliptic curve cryptography (ECC).

with terminal private key

The terminal key pair, the new terminal a3 saves the terminal private key of its own terminal key pair

, and the new terminal b1 saves the terminal private key of its own terminal key pair

.

至伺服器c，且新終端b1上傳自己之終端金鑰對之終端公鑰

至伺服器c。 Procedure P12 (see step S12 in Figure 1): The new terminal a3 and the new terminal b1 upload the terminal public keys of their own terminal key pairs to the server c. For example, the new terminal a3 uploads the terminal public key of its own terminal key pair

to server c, and the new terminal b1 uploads the terminal public key of its own terminal key pair

to server c.

Program P13 (see step S13 in Figure 1): Server c returns the valid terminal information list Passed to new terminal a3 and new terminal b1. For example, server c returns the valid terminal information list [a1, a2, a3] of the first account a to the new terminal a3, and returns the valid terminal information list [b1] of the second account b to the new terminal b1.

Program P14 (see step S14 in Figure 1): The new terminal a3 and the new terminal b1 are respectively judged based on the valid terminal information list [a1, a2, a3] of the first account a and the valid terminal information list [b1] of the second account b. The account key pair should be initialized or updated. For example, since the first account a already has valid terminal a1 and terminal a2, the new terminal a3 needs to update the account key pair. The second account b does not yet have a valid terminal, and the new terminal b1 is the only valid terminal of the second account b, so the new terminal b1 needs to initialize the account key pair.

Figure 8 is a schematic diagram of an embodiment of the "initialization of the account key pair" shown in Figure 2 in the multi-terminal end-to-end encrypted communication method of the present invention. As shown in FIG. 8 , when the scenario of initializing the account key pair is implemented, assuming that the new terminal b1 generates an account key pair, this embodiment may include the following contents from procedures P21 to P23.

與帳號私鑰

之帳號金鑰對。 Procedure P21 (see step S21 in Figure 2): The new terminal b1 generates an account public key through elliptic curve cryptography (ECC).

with account private key

The account key pair.

至伺服器c中儲存，即完成帳號金鑰對之初始化。 Procedure P22 (see step S22 in Figure 2): The new terminal b1 uploads the account public key of the account key pair of the second account b (see Figure 7)

Store it in server c, which completes the initialization of the account key pair.

回應具有唯一值之帳號公鑰識別碼ID予新終端b1。 Procedure P23: Server c can use the account public key of the account key pair of the second account b

Respond to the new terminal b1 with the account public key identification code ID having a unique value.

Figure 9 is a schematic diagram of an embodiment of the "update of account key pair" shown in Figure 3 in the multi-terminal end-to-end encrypted communication method of the present invention. As shown in Figure 9, the account key pair is updated. When implementing this scenario, assuming that the new terminal a3 updates the account key pair, this embodiment may include the following contents from procedures P31 to P39.

。例如，由終端a1(如舊終端)之螢幕以16進位(HEX)等方式顯示第一帳號a目前之帳號私鑰

，再由使用者於新終端a3輸入第一帳號a目前之帳號私鑰

。 Procedure P31 (see step S31 in Figure 3): The new terminal a3 obtains the current account private key of the first account a (see Figure 7) from the terminal a1 (such as the old terminal) without going through the server c.

. For example, the current account private key of the first account a is displayed on the screen of terminal a1 (such as the old terminal) in a hexadecimal (HEX) format.

, and then the user enters the current account private key of the first account a in the new terminal a3

.

與第一更新參數Parm以產生一具有第一新帳號公鑰與第一新帳號私鑰之第一新帳號金鑰對。 Program P32 (see steps S32 to S33 in Figure 3): the new terminal a3 generates the first update parameter Parm (such as a number or a positive integer). Then, the new terminal a3 can use the current account private key of the first account a

and the first update parameter Parm to generate a first new account key pair having a first new account public key and a first new account private key.

XOR Parm，亦即將第一帳號a之帳號私鑰

與第一更新參數Parm兩者進行互斥或(XOR)運算以產生第一新帳號金鑰對之第一新帳號私鑰

。

，亦即依據第一新帳號私鑰

與橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定所使用之橢圓曲線之基點G以產生或推論出第一新帳號金鑰對之第一新帳號公鑰

。 For example, the new terminal a3 calculates the following two formulas:

XOR Parm, which is the account private key of the first account a

Perform a mutually exclusive OR (XOR) operation with the first update parameter Parm to generate the first new account private key of the first new account key pair.

.

, that is, based on the first account private key

The base point G of the elliptic curve used in the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol is used to generate or deduce the first new account public key of the first new account key pair.

.

與第一臨時私鑰

之第一臨時金鑰對，再由新終端a3依序使用多個/所有舊終端(如終端a1與終端a2)之終端公鑰與第一臨時私鑰

以加密第一更新參數Parm。 Procedure P33 (see steps S34 to S35 in Figure 3): The new terminal a3 generates a first temporary public key through elliptic curve cryptography (ECC).

with the first temporary private key

The first temporary key pair, and then the new terminal a3 sequentially uses the terminal public keys and the first temporary private keys of multiple/all old terminals (such as terminal a1 and terminal a2)

To encrypt the first update parameter Parm.

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定將終端a1(如舊終端)之終端公鑰

與新終端a3之第一臨時私鑰

進行運算以產生終端a1(如舊終端)與新終端a3兩者之共享臨時金鑰

。

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定將終端a2(如舊終端)之終端公鑰

與新終端a3之第一臨時私鑰

進行運算以產生終端a2(如舊終端)與新終端a3兩者之共享臨時金鑰

。

，亦即透過進階加密標準(AES)演算法將終端a1(如舊終端)與新終端a3兩者之共享臨時金鑰

配合第一更新參數Parm進行運算以產生終端a1(如舊終端)之更新參數密文CT_Parm^a1。

，亦即透過進階加密標準(AES)演算法將終端a2(如舊終端)與新終端a3兩者之共享臨時金鑰

配合第一更新參數Parm進行運算以產生終端a2(如舊終端)之更新參數密文CT_Parm^a2。 For example, the following four formulas are calculated by the new terminal a3:

, that is, according to the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol, the terminal public key of terminal a1 (such as the old terminal)

With the first temporary private key of the new terminal a3

Perform operations to generate the shared temporary key between terminal a1 (such as the old terminal) and the new terminal a3

.

, that is, according to the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol, the terminal public key of terminal a2 (such as the old terminal)

With the first temporary private key of the new terminal a3

Perform operations to generate the shared temporary key between terminal a2 (such as the old terminal) and the new terminal a3

.

, that is, using the Advanced Encryption Standard (AES) algorithm to share the temporary key between terminal a1 (such as the old terminal) and the new terminal a3.

The calculation is performed in conjunction with the first update parameter Parm to generate the update parameter ciphertext CT_Parm ^a1 of the terminal a1 (such as the old terminal).

, that is, using the Advanced Encryption Standard (AES) algorithm to share the temporary key between terminal a2 (such as the old terminal) and the new terminal a3.

The calculation is performed in conjunction with the first update parameter Parm to generate the update parameter ciphertext CT_Parm ^a2 of the terminal a2 (such as the old terminal).

。 Procedure P34: New terminal a3 uploads update information to server c. For example, this update information may include the following information: (1) the update parameter ciphertext CT_Parm ^a1 of terminal a1 and the update parameter ciphertext CT_Parm ^a2 of terminal a2, (2) the first temporary public key of the new terminal a3

.

Procedure P35: After server c receives the update information from new terminal a3, server c performs a legality check. For example, the validity check of server c may include: (1) confirming that there is no valid account public key for the same terminal set, (2) confirming that the object of the update parameter ciphertext is the same as the valid terminal of the account.

Procedure P36: Server c responds with relevant information to new terminal a3. For example, if the result of the legality check performed by server c is legal, server c responds with a unique account public key identification code ID to the new terminal a3; conversely, if the legality check performed by server c is The result is Illegal, server c responds to the new terminal a3 with a valid terminal information list of the current account (such as the first account a).

Procedure P37: When terminal a1 or terminal a2 (such as the old terminal) comes online, server c will synchronize the update information to terminal a1 or terminal a2 (such as the old terminal).

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定將新終端a3之第一臨時公鑰

與終端a1(如舊終端)自己之終端金鑰對之終端私鑰

進行運算以產生終端a1(如舊終端)與新終端a3兩者之共享臨時金鑰

。

，亦即透過進階加密標準(AES)演算法以使用終端a1(如舊終端)與新終端a3兩者之共享臨時金鑰

配合終端a1之更新參數密文CT_Parm^a1來解密出第一更新參數Parm。 Procedure P38: Terminal a1 or terminal a2 (such as the old terminal) uses the terminal private key of its own terminal key pair to decrypt the first update parameter Parm. For example, the following two formulas are calculated by terminal a1 (such as the old terminal):

, that is, according to the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol, the first temporary public key of the new terminal a3

The terminal private key paired with terminal a1 (such as the old terminal)'s own terminal key

Perform operations to generate the shared temporary key between terminal a1 (such as the old terminal) and the new terminal a3

.

, that is, using the Advanced Encryption Standard (AES) algorithm to use the shared temporary key between terminal a1 (such as the old terminal) and the new terminal a3

Cooperate with the update parameter ciphertext CT_Parm ^a1 of the terminal a1 to decrypt the first update parameter Parm.

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定將新終端a3之第一臨時公鑰

與終端a2(如舊終端)自己之終端金鑰對之終端私鑰

進行運算以產生終端a2(如舊終端)與新終端a3兩者之共享臨時金鑰

。

，亦即透過進階加密標準(AES)演算法以使用終端a2(如舊終端)與新終端a3兩者之共享臨時金鑰

配合終端a2之更新參數密文CT_Parm^a2來解密出第一更新參數Parm。 In addition, the following two formulas are calculated by terminal a2 (like the old terminal):

, that is, according to the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol, the first temporary public key of the new terminal a3

Terminal private key paired with terminal a2 (like the old terminal)'s own terminal key

Perform operations to generate the shared temporary key between terminal a2 (such as the old terminal) and the new terminal a3

.

, that is, using the Advanced Encryption Standard (AES) algorithm to use the shared temporary key between terminal a2 (such as the old terminal) and the new terminal a3

Cooperate with the update parameter ciphertext CT_Parm ^a2 of terminal a2 to decrypt the first update parameter Parm.

，亦即將第一帳號a之帳號私鑰

與第一更新參數Parm兩者進行互斥或(XOR)運算以產生第一新帳號金鑰對之第一新帳號私鑰

。

，亦即依據第一新帳號私鑰

與橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定所使用之橢圓曲線之基點G以產生或推論出第一新帳號金鑰對之第一新帳號公鑰

。 Procedure P39 (see step S38 in Figure 3): Terminal a1 or terminal a2 (such as the old terminal) updates its account key pair. For example, the following two formulas are calculated by terminal a1 or terminal a2 (such as the old terminal):

, that is, the account private key of the first account a

Perform a mutually exclusive OR (XOR) operation with the first update parameter Parm to generate the first new account private key of the first new account key pair.

.

, that is, based on the first account private key

The base point G of the elliptic curve used in the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol is used to generate or deduce the first new account public key of the first new account key pair.

.

Figure 10 is a schematic diagram of an embodiment of "removing the terminal" shown in Figure 4 in the multi-terminal end-to-end encrypted communication method of the present invention. As shown in Figure 10, when the scenario of removing the terminal is implemented, assuming that the user wants to remove the new terminal a3 through the terminal a1 (such as the operating terminal) of the first account a (see Figure 7), then this embodiment may include the following procedures Contents from P41 to Program P49.

與第二新帳號私鑰

之第二新帳號金鑰對。 Program P41 (see steps S41 to S42 in Figure 4): Terminal a1 (such as an operation terminal) generates the second update parameter Parm, and the terminal a1 (such as an operation terminal) can generate a public key with a second new account

with the second new account private key

The second new account key pair.

，亦即將第一帳號a之帳號私鑰

與第二更新參數Parm兩者進行互斥或(XOR)運算以產生第二新帳號金鑰對之第二新帳號私鑰

。

，亦即依據第二新帳號私鑰

與橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定所使用之橢圓曲線之基點G以產生或推論出第二新帳號金鑰對之第二新帳號公鑰

。 For example, the following two formulas are calculated by terminal a1 (such as an operation terminal):

, that is, the account private key of the first account a

Perform a mutually exclusive OR (XOR) operation with the second update parameter Parm to generate the second new account private key of the second new account key pair.

.

, that is, based on the second account private key

Use the base point G of the elliptic curve used in the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol to generate or deduce the second account public key of the second account key pair.

.

與第二臨時私鑰

之第二臨時金鑰對。然後，終端a1(如操作終端)可將第二更新參數Parm加密成終端a2之更新參數密文CT_Parm^a2。 Procedure P42 (see step S43 in Figure 4): Terminal a1 (such as an operating terminal) generates a second temporary public key through elliptic curve cryptography (ECC).

with the second temporary private key

The second temporary key pair. Then, the terminal a1 (such as an operation terminal) can encrypt the second update parameter Parm into the update parameter ciphertext CT_Parm a2 of the terminal ^a2 .

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定將終端a2之終端公鑰

與終端a1(如操作終端)之第二臨時私鑰

進行運算以產生終端a1(如操作終端)與終端a2兩者之共享臨時金鑰

。

，亦即透過進階加密標準(AES)演算法使用終端a1(如操作終端)與終端a2兩者之共享臨時金鑰

將第二更新參數Parm加密成終端a2之更新參數密文CT_Parm^a2。 For example, the following two formulas are calculated by terminal a1 (such as an operation terminal):

, that is, according to the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol, the terminal public key of terminal a2

and the second temporary private key of terminal a1 (such as operating terminal)

Perform operations to generate a shared temporary key between terminal a1 (such as an operating terminal) and terminal a2

.

, that is, using the shared temporary key between terminal a1 (such as an operating terminal) and terminal a2 through the Advanced Encryption Standard (AES) algorithm.

The second update parameter Parm is encrypted into the update parameter ciphertext CT_Parm ^a2 of terminal a2.

，(3)新終端a3(如欲移除之終端)之終端識別碼ID。 Procedure P43: Terminal a1 (such as an operation terminal) uploads update information to server c. For example, this update information may include the following information: (1) the update parameter ciphertext CT_Parm ^a2 of terminal a2, (2) the second temporary public key of terminal a1 (such as an operation terminal)

, (3) The terminal identification code ID of the new terminal a3 (such as the terminal to be removed).

Program P44 (see step S46 in Figure 4): After server c receives the update information from terminal a1 (such as an operation terminal), server c performs a legality check. For example, this legality check may include: (1) confirming that there is no valid account public key for the same terminal set, (2) confirming that the object of the update parameter ciphertext is the same as the valid terminal of the account (excluding the terminal to be removed). If the result of the validity check performed by server c is legal, server c will invalidate the new terminal a3.

Procedure P45: Server c responds with relevant information to terminal a1 (such as operating terminal). For example, if the result of the legality check performed by server c is legal, server c responds with a unique account public key identification code ID to terminal a1 (such as an operation terminal); otherwise, if the result of the legality check performed by server c is If the result of the legality check is illegal, the server c responds to the terminal a1 (such as the operating terminal) with a valid terminal information list of the current account (such as the first account a).

Procedure P46 (see step S46 in Figure 4): Server c notifies the new terminal a3 that it has been removed This new terminal a3.

Procedure P47: When terminal a2 comes online, server c will synchronize the update information to terminal a2.

進行解密以得到第二更新參數Parm。例如，由終端a2運算下列二個公式：

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定將終端a1(如操作終端)之第二臨時公鑰

與終端a2自己之終端金鑰對之終端私鑰

進行運算以產生終端a1(如操作終端)與終端a2兩者之共享臨時金鑰

。

，亦即透過進階加密標準(AES)演算法以使用終端a1(如操作終端)與終端a2兩者之共享臨時金鑰

配合終端a2之更新參數密文CT_Parm^a2來解密出第二更新參數Parm。 Procedure P48: Terminal a2 uses the terminal private key of its own terminal key pair

Decrypt to obtain the second update parameter Parm. For example, the following two formulas are calculated by terminal a2:

, that is, according to the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol, the second temporary public key of terminal a1 (such as an operating terminal)

Terminal private key paired with terminal a2's own terminal key

Perform operations to generate a shared temporary key between terminal a1 (such as an operating terminal) and terminal a2

.

, that is, using the Advanced Encryption Standard (AES) algorithm to use the shared temporary key between terminal a1 (such as an operating terminal) and terminal a2

Cooperate with the update parameter ciphertext CT_Parm ^a2 of terminal a2 to decrypt the second update parameter Parm.

Parm，亦即將第一帳號a之帳號私鑰

與第二更新參數Parm兩者進行互斥或(XOR)運算以產生第二新帳號金鑰對之第二新帳號私鑰

。

，亦即依據第二新帳號私鑰

與橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定所使用之橢圓曲線之基點G以產生或推論出第二新帳號金鑰對之第二新帳號公鑰

。 Procedure P49 (see step S48 in FIG. 4 ): Terminal a2 (such as other terminals) updates its own account key pair. For example, terminal a2 calculates the following two formulas:

Parm, that is, the private key of the first account a

Perform an exclusive OR (XOR) operation with the second update parameter Parm to generate the second new account private key of the second new account key pair

.

, that is, based on the private key of the second new account

The second new account public key of the second new account key pair is generated or inferred from the base point G of the elliptical curve used in the ECDH protocol

.

Figure 11 is a schematic diagram of an embodiment of "sending and receiving messages" shown in Figure 5 in the multi-terminal end-to-end encrypted communication method of the present invention. As shown in Figure 11, when the scenario of sending and receiving messages is implemented, it is assumed that the second account b (see Figure 7) has successfully added a new terminal b2, and the terminal a1 (such as the sending terminal) initially To send a message to the second account b once, this embodiment may include the following contents from program P51 to program P65.

(如第一代棘輪金鑰)。 Procedure P51 (see step S51 in Figure 5): Terminal a1 (such as the sending terminal) selects the second account b as the receiving account, and confirms that no ratchet key is generated for the second account b (such as the receiving account)

(Such as the first generation ratchet key).

與第三臨時私鑰

之第三臨時金鑰對。 Procedure P52 (see step S52 in Figure 5): Terminal a1 (such as the sending terminal) generates a third temporary public key

with the third temporary private key

The third temporary key pair.

(如第一代棘輪金鑰)。例如，由終端a1(如發訊終端)運算下列公式：

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定以使用第二帳號b(如收訊帳號)之帳號公鑰

與終端a1(如發訊終端)之第三臨時私鑰

計算出棘輪金鑰

(如第一代棘輪金鑰)。 Program P53 (see step S52 in Figure 5): Terminal a1 (such as the sending terminal) calculates the ratchet key

(Such as the first generation ratchet key). For example, terminal a1 (such as the sending terminal) calculates the following formula:

, that is, based on the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol to use the account public key of the second account b (such as the receiving account)

and the third temporary private key of terminal a1 (such as the sending terminal)

Calculate the ratchet key

(Such as the first generation ratchet key).

(如第一代棘輪金鑰)與第一常數衍生出訊息金鑰

，並由終端a1(如發訊終端)使用第二常數將棘輪金鑰

(如第一代棘輪金鑰)更新成下一代棘輪金鑰

(如第二代棘輪金鑰)。 Program P54 (see step S53 in Figure 5): Terminal a1 (such as the sending terminal) uses the ratchet key

(such as the first generation ratchet key) and the first constant to derive the message key

, and the terminal a1 (such as the sending terminal) uses the second constant to change the ratchet key

(such as the first generation ratchet key) updated to the next generation ratchet key

(Such as the second generation ratchet key).

，亦即使用金鑰雜湊訊息認證碼(HMAC)配合第一常數(如0x1)將棘輪金鑰

(如第一代棘輪金鑰)衍生為訊息金鑰

(如第一代訊息金鑰)。

，亦即使用第二常數(如0x2)將棘輪金鑰

(如第一代棘輪金鑰)更新成下一代棘輪金鑰

(如第二代棘輪金鑰)。 For example, terminal a1 (such as the sending terminal) calculates the following two formulas:

, that is, using the key hash message authentication code (HMAC) and the first constant (such as 0x1) to convert the ratchet key

(such as the first generation ratchet key) is derived as a message key

(Such as the first generation message key).

, that is, using a second constant (such as 0x2) to change the ratchet key

(such as the first generation ratchet key) updated to the next generation ratchet key

(Such as the second generation ratchet key).

Message)，亦即透過進階加密標準(AES)演算法以使用訊息金鑰

(如第一代訊息金鑰)將訊息Message進行加密而產生訊息密文

。 Procedure P55 (see step S54 in Figure 5): The terminal a1 (such as the sending terminal) uses the message key to encrypt the message Message to generate the message ciphertext CT_Message ^a1_b . For example, terminal a1 (such as the sending terminal) calculates the following formula:

Message), that is, using the message key through the Advanced Encryption Standard (AES) algorithm

(such as the first generation message key) encrypts the message to generate the message ciphertext

.

(如第一代棘輪金鑰)。 Procedure P56: Terminal a1 (such as the sending terminal) selects the first account a as the receiving account and confirms that no ratchet key is generated for the first account a

(Such as the first generation ratchet key).

與第三臨時私鑰

。 Procedure P57: Terminal a1 (such as the sending terminal) generates the third temporary public key of terminal a1

with the third temporary private key

.

(如第一代棘輪金鑰)。例如，由終端a1(如發訊終端)運算下列公式：

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定以使用第一帳號a之帳號公鑰

與終端a1(如發訊終端)之第三臨時私鑰

計算出棘輪金鑰

(如第一代棘輪金鑰)。 Program P58: Terminal a1 (such as the sending terminal) calculates the ratchet key

(Such as the first generation ratchet key). For example, terminal a1 (such as the sending terminal) calculates the following formula:

, that is, using the account public key of the first account a according to the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol

and the third temporary private key of terminal a1 (such as the sending terminal)

Calculate the ratchet key

(Such as the first generation ratchet key).

(如第一代棘輪金鑰)衍生出訊息金鑰

(如第一代訊息金鑰)，並使用第二常數將棘輪金鑰

(如第一代棘輪金鑰)更新成下一代棘輪金鑰

(如第二代棘輪金鑰)。 Procedure P59: Terminal a1 (such as the sending terminal) uses the ratchet key

(such as the first generation ratchet key) derived from the message key

(such as the first generation message key), and use the second constant to convert the ratchet key

(such as the first generation ratchet key) updated to the next generation ratchet key

(Such as the second generation ratchet key).

，亦即使用金鑰雜湊訊息認證碼(HMAC)配合第一常數(如0x1)將棘輪金鑰

(如第一代棘輪金鑰)衍生為訊息金鑰

(如第一代訊息金鑰)。

，亦即使用第二常數(如0x2)將棘輪金鑰

(如第一代棘輪金鑰)更新成下一代棘輪金鑰

(如第二代棘輪金鑰)。 For example, terminal a1 (such as the sending terminal) calculates the following two formulas:

, that is, using the key hash message authentication code (HMAC) and the first constant (such as 0x1) to convert the ratchet key

(such as the first generation ratchet key) is derived as a message key

(Such as the first generation message key).

, that is, using a second constant (such as 0x2) to change the ratchet key

(such as the first generation ratchet key) updated to the next generation ratchet key

(Such as the second generation ratchet key).

，亦即透過進階加密標準(AES)演算法以使用訊息金鑰

(如第一代訊息金鑰)將訊息Message進行加密而產生訊息密文CT_Message^a1_a。 Procedure P60: The terminal a1 (such as the sending terminal) encrypts the message Message to generate the message ciphertext CT_Message ^a1_a . For example, terminal a1 (such as the sending terminal) calculates the following formula:

, that is, using the message key through the Advanced Encryption Standard (AES) algorithm

(such as the first generation message key) encrypts the message Message to generate the message ciphertext CT_Message ^a1_a .

Procedure P61 (see step S56 in Figure 5): Terminal a1 (such as the sending terminal) uploads the message ciphertext and key information to server c. For example, the message ciphertext and key information about the first account a may include: (1) message ciphertext CT_Message ^a1_a , (2) key information (the account public key identification code ID used, the algebra of the ratchet key), (3) If the ratchet key is a first-generation ratchet key, a third temporary public key needs to be included (additional). In addition, the message ciphertext and key information about the second account b (such as the receiving account) may include: (1) message ciphertext CT_Message ^a1_b , (2) key information (account public key identification code ID, ratchet The algebra of the key), (3) If the ratchet key is a first-generation ratchet key, a third temporary public key needs to be included (additional).

Program P62 (see step S57 in Figure 5): After receiving the message ciphertext, server c checks whether the account public key is valid. If the account public key is valid, server c responds that the account public key is valid. Valid relevant information (such as correct or successful) is sent to terminal a1 (such as the sending terminal), and the message ciphertext is stored; on the contrary, if the account public key is invalid, server c responds with relevant information that the account public key is invalid (such as error or failure) to terminal a1 (such as the sending terminal).

Procedure P63 (see step S58 in Figure 5): After the terminal a2, the new terminal b1 or the new terminal b2 (such as the receiving terminal) comes online, the corresponding message ciphertext (encrypted message) is received from the server c.

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定以使用終端a1(如發訊終端)之第三臨時公鑰

與第二帳號b(如收訊帳號)之帳號私鑰

計算出對應之棘輪金鑰

。此外，由終端a2(如收訊終端)運算下列公式：

，亦即依據橢圓曲線迪菲-赫爾曼金鑰交換(ECDH)協定以使用終端a1(如發訊終端)之第三臨時公鑰

與第一帳號a之帳號私鑰

計算出對應之棘輪金鑰

。 Program P64 (see step S59 in Figure 5): Terminal a2, new terminal b1 or new terminal b2 (such as the receiving terminal) derives the corresponding ratchet key. For example, the following formula is calculated by the new terminal b1 or new terminal b2 (such as the receiving terminal):

, that is, based on the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol to use the third temporary public key of terminal a1 (such as the sending terminal)

and the account private key of the second account b (such as the receiving account)

Calculate the corresponding ratchet key

. In addition, the terminal a2 (such as the receiving terminal) calculates the following formula:

, that is, based on the Elliptic Curve Diffie-Hellman Key Exchange (ECDH) protocol to use the third temporary public key of terminal a1 (such as the sending terminal)

and the account private key of the first account a

Calculate the corresponding ratchet key

.

，亦即使用金鑰雜湊訊息認證碼(HMAC)配合第一常數(如0x1)將棘輪金鑰

(如第一代棘輪金鑰)衍生為訊息金鑰

(如第一代訊息金鑰)。

，亦即使用金鑰雜湊訊息認證碼(HMAC)配合第二常數(如0x2)將棘輪金鑰

(如第一代棘輪金鑰)更新成下一代棘輪金鑰

(如第二代棘輪金鑰)。

CT_Message^a1_b)，亦即透過進階加密標準(AES)演算法以使用訊息金鑰

(如第一代訊息金鑰)與訊息密文CT_Message^a1_b解密出訊息Message。 Procedure P65 (see step S59 in Figure 5): The terminal a2, the new terminal b1 or the new terminal b2 (such as the receiving terminal) uses the first constant or the second constant to decrypt the message (message ciphertext). For example, the following three formulas are calculated by the new terminal b1 or new terminal b2 (such as the receiving terminal):

, that is, using the key hash message authentication code (HMAC) and the first constant (such as 0x1) to convert the ratchet key

(such as the first generation ratchet key) is derived as a message key

(Such as the first generation message key).

, that is, using the key hash message authentication code (HMAC) and the second constant (such as 0x2) to convert the ratchet key

(such as the first generation ratchet key) updated to the next generation ratchet key

(Such as the second generation ratchet key).

CT_Message ^a1_b ), that is, using the message key through the Advanced Encryption Standard (AES) algorithm

(such as the first-generation message key) and the message ciphertext CT_Message ^a1_b to decrypt the message Message.

，亦即使用金鑰雜湊訊息認證碼(HMAC)配合第一常數(如0x1)將棘輪金鑰

(如第一代棘輪金鑰)衍生為訊息金鑰

(如第一代訊息金鑰)。

，亦即使用金鑰雜湊訊息認證碼(HMAC)配合第二常數(如0x2)將棘輪金鑰

(如第一代棘輪金鑰)更新成下一代棘輪金鑰

(如第二代棘輪金鑰)。

Message=AESdecrypt

，亦即透過進階加密標準(AES)演算法以使用訊息金鑰

(如第一代訊息金鑰)與訊息密文CT_Message^a1_a解密出訊息Message。 In addition, the following three formulas are calculated by terminal a2 (such as the receiving terminal):

, that is, using the key hash message authentication code (HMAC) and the first constant (such as 0x1) to convert the ratchet key

(such as the first generation ratchet key) is derived as a message key

(Such as the first generation message key).

, that is, using the key hash message authentication code (HMAC) and the second constant (such as 0x2) to convert the ratchet key

(such as the first generation ratchet key) updated to the next generation ratchet key

(Such as the second generation ratchet key).

Message=AES decrypt

, that is, using the message key through the Advanced Encryption Standard (AES) algorithm

(such as the first-generation message key) and the message ciphertext CT_Message ^a1_a to decrypt the message Message.

Furthermore, the present invention also provides a computer-readable medium for an end-to-end encrypted communication method for multiple terminals, which is applied to a computing device or computer with a processor and/or memory, and the computer-readable medium stores a voice message. instructions, and can utilize a computing device or computer to execute the computer-readable medium through a processor and/or memory to execute the above content when the computer-readable medium is executed.

In one embodiment, the processor may be a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), a microcontroller (MCU), etc., and the memory may be a random access memory (RAM), a unique memory (RAM), or a random access memory (RAM). Read memory (ROM), memory card, hard drive (such as cloud/network/external hard drive), optical disk, pen drive, database, etc., and the computing device or computer can be a computer, tablet, personal computer, notebook type computer, Desktop computers, servers (such as cloud/remote/network servers), smartphones, etc., but are not limited to this.

In summary, the multi-terminal end-to-end encrypted communication method and computer-readable medium of the present invention have at least the following features, advantages or technical effects.

1. When the user owns multiple terminals (such as a sending terminal/receiving terminal), the user can simultaneously use multiple terminals to send and receive message ciphertext (encrypted messages), and the messages between the terminals can be maintained. consistent.

2. The present invention enables message consistency between terminals, so that when a user uses any terminal to send or receive a message, the user's other terminals can automatically synchronize the message.

3. The present invention enables multiple (all) user terminals to have the same account key pair, so that when the number of user terminals increases, the number of message ciphertexts (encrypted messages) sent will not increase. .

4. The present invention uses multiple terminals of the same user to share the same account key pair. When the terminal (such as the sending terminal) sends a message, the terminal performs key exchange with the account public key of the receiving account, and then uses the ratchet key. The message key is derived to encrypt the message. This message can be decrypted by multiple (all) terminals of the receiving account, which is conducive to end-to-end encryption of the account by the terminal, and the ciphertext of the message sent by the terminal (encrypted The number of messages) will not increase as the number of user terminals increases.

5. The sending terminal of the present invention can only send one message ciphertext (encrypted message), so that multiple (all) terminals under the receiving account can decrypt the message ciphertext (encrypted message).

6. The message key of the present invention is generated through negotiation between multiple terminals. There is no need to upload the message key to the server, and the message key does not need to be encrypted in any form.

7. The present invention can update the account key pair when the user changes the terminal and Synchronization mechanism to achieve end-to-end encryption protection even after the terminal changes.

8. When the user changes the terminal, the present invention can ensure the security of end-to-end encryption by updating the account key pair, so that the new terminal can receive and decrypt the new message ciphertext (encrypted message), and The removed terminal cannot receive and decrypt new messages.

9. When the user changes the terminal, the terminal of the present invention will update the account key pair and synchronize and update the user's other terminals to ensure that the account key pairs of each terminal are consistent.

10. The present invention can use a ratchet key (ratchet method) to generate a message key to ensure forward security or forward secrecy (FS) of the message or message key.

11. The message key used in the message encryption of the present invention is generated through a one-way hash function (such as the key hash message authentication code HMAC), so even if a third party (such as a hacker) obtains contemporary messages The key cannot be reversely deduced from the previous (such as the previous generation) message key, so as to maintain the forward security or forward secrecy (FS) of the message or message key.

12. Multiple (all) terminals of the same user of the present invention can have the same account key pair. When a terminal wants to send a message, Elliptic Curve Diffie-Hellman Key Exchange (ECDH) can be used. ) protocol and key ratchet method, the temporary private key and the account public key of the receiving account are calculated to obtain the message key to encrypt the message, so that the number of sent message ciphertext (encrypted message) is not affected by the user's terminal Affected by quantity, forward security or forward secrecy (FS) of messages or message keys can also be maintained.

The above embodiments are only illustrative of the principles, characteristics and effects of the present invention, and are not intended to limit the scope of the present invention. Anyone skilled in the art can make the above-mentioned modifications without violating the spirit and scope of the present invention. Modify and change the implementation form. Any equivalent changes and modifications made using the contents disclosed in the present invention shall still be covered by the patent application. therefore, The scope of protection of the rights of the present invention shall be as listed in the patent application scope.

S51 to S59: Steps

Claims (14)

An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated with the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the message key is derived from the ratchet key for the receiving account. The sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; And the server sends the message ciphertext and the key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, each receiving terminal The key information sent by the server is used to generate the message key corresponding to the ratchet key, so that each receiving terminal can use the message key corresponding to the ratchet key to decrypt the message ciphertext. The message; wherein, the multi-terminal end-to-end encrypted communication method further includes: the new terminal generates a terminal key pair with a terminal public key and a terminal private key through elliptic curve cryptography, so as to be uploaded by the new terminal The terminal public key of the terminal key pair is sent to the server, and then the server returns the valid terminal information list under the user's current account to the new terminal, so that the new terminal can make judgments based on the valid terminal information list. The account key pair should be initialized or updated. An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated on the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; The sending terminal uses the ratchet key of the receiving account to derive a message key, and then the sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate The message ciphertext allows the sending terminal to upload the message ciphertext and key information to the server; and the server sends the message ciphertext and key information to multiple recipients under the receiving account. When each receiving terminal receives the message ciphertext, each receiving terminal uses the key information sent by the server to generate the message key corresponding to the ratchet key. Each receiving terminal uses the message key corresponding to the ratchet key to decrypt the message from the message ciphertext; wherein, the multi-terminal end-to-end encrypted communication method further includes: the new terminal uses elliptic curve cryptography Generate an account key pair with an account public key and an account private key, and upload the account public key of the account key pair from the new terminal to the server for storage to complete the initialization of the account key pair, and then The server responds to the new terminal with a unique account public key identification code based on the account public key of the account key pair. An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated with the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the message key is derived from the ratchet key for the receiving account. The sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; And the server sends the message ciphertext and the key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, each receiving terminal Use this server The key information sent by the server is used to generate the message key corresponding to the ratchet key, so that each receiving terminal can use the message key corresponding to the ratchet key to decrypt the message from the message ciphertext. ; Among them, the end-to-end encrypted communication method of multiple terminals further includes: the new terminal obtains the current account private key from the old terminal through a method other than the server, and the new terminal generates update parameters to use the new terminal. The terminal uses the current account private key and the update parameters to generate a new account key pair with a new account public key and a new account private key, and then the new terminal generates a first temporary public key pair through elliptic curve cryptography. A first temporary key pair with a first temporary private key. An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated with the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the message key is derived from the ratchet key for the receiving account. The sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; And the server sends the message ciphertext and the key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, each receiving terminal The key information sent by the server is used to generate the message key corresponding to the ratchet key, so that each receiving terminal can use the message key corresponding to the ratchet key to decrypt the message ciphertext. The message; wherein, the multi-terminal end-to-end encrypted communication method further includes: the new terminal uses the terminal public key of the old terminal and the first temporary private key of the first temporary key pair to encrypt the updated parameters, so that the new terminal uses The new terminal uploads the new account public key, the first temporary public key and the encrypted update parameters to the server. The server then synchronizes the encrypted update parameters to the old terminal so that the old terminal can update its own account key pair. A multi-terminal end-to-end encrypted communication method, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account The public key is calculated with the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the message key is derived from the ratchet key for the receiving account. The sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; And the server sends the message ciphertext and the key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, each receiving terminal Use the key information sent by the server to generate the message key corresponding to the ratchet key, so that each receiving terminal can use the message key corresponding to the ratchet key to decrypt the message ciphertext. The message; wherein, the multi-terminal end-to-end encrypted communication method further includes: generating update parameters by the operation terminal, so that the operation terminal uses the current account private key and the update parameters to generate a new account public key and a new account The new account key pair of the private key is then used by the operation terminal to generate another temporary key pair with another temporary public key and another temporary private key through elliptic curve cryptography. An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated on the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; The sending terminal uses the ratchet key of the receiving account to derive a message key, and then the sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate The message ciphertext allows the sending terminal to upload the message ciphertext and key information to the server; and the server sends the message ciphertext and key information to multiple recipients under the receiving account. When each receiving terminal receives the message ciphertext, each receiving terminal uses the key information sent by the server to generate the message key corresponding to the ratchet key. Each receiving terminal uses the message key corresponding to the ratchet key to decrypt the message from the message ciphertext; wherein, the multi-terminal end-to-end encrypted communication method further includes: the operation terminal uses the message to be removed The terminal public key and another temporary private key of other terminals other than the terminal are used to encrypt the update parameters, so that the operation terminal combines the new account public key, another temporary public key, the encrypted update parameters and the one to be removed. The terminal identification code of the terminal is uploaded to the server, and then the server invalidates the terminal to be removed, so that the server can synchronize the encrypted update parameters to other terminals except the terminal to be removed. Then, other terminals other than the terminal to be removed update their own account key pairs. An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated with the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the message key is derived from the ratchet key for the receiving account. The sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; as well as The server sends the message ciphertext and the key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, it can be used by each receiving terminal. The key information sent by the server is used to generate the message key corresponding to the ratchet key, so that each receiving terminal uses the message key corresponding to the ratchet key to decrypt the message ciphertext. message; wherein, the multi-terminal end-to-end encrypted communication method further includes: the server checks the validity of the account public key of the receiving account. If the account public key is invalid, the server replies with the latest account number The public key is given to the sending terminal so that the sending terminal regenerates the ratchet key and discards the message ciphertext. If the account public key is valid, the server combines the message ciphertext and the key information. Sent to the multiple receiving terminals under the receiving account. The end-to-end encrypted communication method for multiple terminals as described in claim 7 further includes the step of using the key hash message authentication code and the first constant to derive the ratchet key as the message key by the sending terminal. The sending terminal uses the message key to perform symmetric encryption of the message to generate the message ciphertext, and then the receiving terminal uses the message key to decrypt the message ciphertext to obtain the message. An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated with the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the message key is derived from the ratchet key for the receiving account. The sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; as well as The server sends the message ciphertext and the key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, it can be used by each receiving terminal. The key information sent by the server is used to generate the message key corresponding to the ratchet key, so that each receiving terminal uses the message key corresponding to the ratchet key to decrypt the message ciphertext. message; wherein, the multi-terminal end-to-end encrypted communication method further includes: the new terminal performs a mutual exclusive OR operation on the account private key and the update parameter to generate a new account private key of the new account key pair, and the new account private key is generated by the new terminal. The new terminal generates or infers the new account public key of the new account key pair based on the new account private key of the new account key pair and the base point of the elliptic curve used in the elliptic curve Diffie-Hellman key exchange protocol. , and then the new terminal generates a first temporary key pair with a first temporary public key and a first temporary private key through elliptic curve cryptography. An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated with the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the message key is derived from the ratchet key for the receiving account. The sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; And the server sends the message ciphertext and the key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, each receiving terminal The key information sent by the server is used to generate the message key corresponding to the ratchet key, so that each receiving terminal can use the message key corresponding to the ratchet key to decrypt the message ciphertext. the message; Among them, the end-to-end encrypted communication method of multiple terminals further includes: the new terminal calculates the terminal public key of the old terminal and the first temporary private key of the new terminal according to the elliptic curve Diffie-Hellman key exchange protocol. To generate a shared temporary key between the old terminal and the new terminal, and then the new terminal uses the Advanced Encryption Standard algorithm to calculate the shared temporary key between the old terminal and the new terminal with the updated parameters. To generate the updated parameter ciphertext of the old terminal. An end-to-end encrypted communication method for multiple terminals, including: the sending terminal generates a temporary key pair with a temporary public key and a temporary private key for the receiving account, and then the sending terminal generates the account number of the receiving account. The public key is calculated with the temporary private key of the temporary key pair to generate a ratchet key for the receiving account; the sending terminal uses the ratchet key for the receiving account to derive the message key, and then the message key is derived from the ratchet key for the receiving account. The sending terminal uses the message key derived from the ratchet key of the receiving account to encrypt the message to generate message ciphertext, so that the sending terminal uploads the message ciphertext and key information to the server; And the server sends the message ciphertext and the key information to multiple receiving terminals under the receiving account, so that when each receiving terminal receives the message ciphertext, each receiving terminal The key information sent by the server is used to generate the message key corresponding to the ratchet key, so that each receiving terminal can use the message key corresponding to the ratchet key to decrypt the message ciphertext. The message; wherein, the multi-terminal end-to-end encrypted communication method further includes: after the server receives the update information from the new terminal, the server performs a legality check, wherein the legality check of the server Including: confirming that there is no valid account public key for the same terminal set, and confirming that the object of the update parameter ciphertext is the same as the valid terminal of the account. The end-to-end encrypted communication method for multiple terminals as described in claim 11, further comprising the step of using the account public key by the sending terminal according to the elliptic curve Diffie-Hellman key exchange protocol. The ratchet key is calculated with the temporary private key of the messaging terminal, and the messaging terminal uses the ratchet key and the first constant to derive the message key, and the messaging terminal uses the second constant to derive the message key. The ratchet key is updated to the next generation ratchet key. The end-to-end encrypted communication method for multiple terminals as described in claim 11 further includes: the sending terminal using a key hash message authentication code and a first constant to derive the ratchet key as the message key, and using the key hash message authentication code and the first constant The sending terminal uses the second constant to update the ratchet key to the next generation ratchet key. A computer-readable medium, used in a computing device or computer, stores instructions to execute the multi-terminal end-to-end encrypted communication method described in any one of claims 1 to 13.

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