CN1620005A - Method of safety transmitting key - Google Patents

Abstract

The invention discloses a method for securely sending a transmission key. The shared key is set separately at both communication parties in advance. The method includes: the sending end generates a random number R1, and then uses the generated random number R1, shared key, and The transmission key and the selected encryption algorithm generate the encryption key Kc, and calculate its own digest word; the sender sends the information carrying the calculated digest word, the generated random number R1 and the encryption key Kc to Receiver: After receiving the information, the receiver first obtains the transmission key according to the shared key, the received random number R1, the encryption key Kc and the selected encryption algorithm; calculates its own signature, and then judges the calculation Whether the signed word is consistent with the received digest word, if yes, the received information is correct information; otherwise, the received information is wrong information. This method can not only make the key secret transmission between two entities, but also ensure mutual identity authentication between entities.

Description

A method for securely sending transmission keys

technical field

The invention relates to data security transmission technology, in particular to a method for securely sending a transmission key under the client-server framework.

Background technique

In various communication systems, especially mobile communication systems, in order to ensure the security and confidentiality of information between users, the realization of secure communication is very important, which requires encrypted protection of the transmitted data, and then requires Encrypted keys are determined and transmitted between entities. In some client-server (C-S, Client-Server) framework applications, only two-party key transmission is involved. For example: in a wireless local area network (WLAN) system, the key transmission between the access controller (AC) and the access point (AP), and the key transmission between the AP and the terminal (STA) all belong to the Client-Server framework Under the key transmission, here, one party can be used as Client, and the other party can be used as Server. Whether between STAs and APs or between APs and ACs, if security protection is not implemented, there will be security risks. Therefore, when the two parties transmit the key, they need to protect the transmitted key information, and also need to authenticate the identities of the two parties to ensure that the mutual key transmission is between legitimate users.

At present, between any two entities that carry out encrypted data transmission, only symmetric keys are manually set during network construction, and no key transmission mechanism is adopted. When confidential information is to be transmitted between two entities, one end uses the set key to encrypt, and the other end uses the same key to decrypt, and a one-way message transmission completes the process of confidential information transmission. However, this method can only perform simple confidential information transmission, and the two ends of the transmission of confidential information cannot perform mutual authentication, so it cannot resist the attack of the middleman.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for safely sending a transmission key, so that it can ensure the secret transmission of the key between two entities.

A further object of the present invention is to ensure mutual identity authentication between two entities.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A method for securely sending a transmission key, in which a shared key K _i is set in advance at both communication parties, the method further includes:

a. The sender generates a random number R1, and then uses the generated random number R1, the shared key K _i , the transmission key master_key to be sent, and the selected encryption algorithm to generate an encryption key Kc, and calculates its own digest word ;

b. The sending end sends the information carrying the digest word calculated in step a, the generated random number R1 and the encryption key Kc to the receiving end;

c. After receiving the information sent in step b, the receiving end first obtains the transmission key master_key according to the shared key K _i , the received random number R1, the encryption key Kc and the selected encryption algorithm; and calculates its own Signature word, and then judge whether the calculated signature word is consistent with the received digest word, if yes, the received information is correct information; otherwise, the received information is wrong information.

Wherein, the digest word in step a is calculated according to the random number R1, the encryption key Kc, the transmission key master_key to be sent and the selected signature word algorithm.

The method further includes:

d. The receiving end randomly generates a random number R2, and calculates the digest word R2-R for authentication, and then sends the generated random number R2 and the calculated digest word R2-R to the sending end;

e. The sender calculates the signature used by itself based on the received random number R2, the encryption key Kc generated by itself, the selected signature algorithm f2, and the transmission key master_key to be sent, and then judges the calculated signature Whether it is equal to the received summary word R2-R, if they are equal, the peer end is the legal party through the authentication, otherwise, the peer end is the illegal party, and the current authentication process ends;

f. The sending end calculates the digest word R2_digt for authentication according to the received random number R2, the shared key K _i and the selected signature algorithm f2, and sends the digest word R2_digt to the receiving end;

g. The receiving end calculates the signature word used by itself according to the random number R2 generated by itself, the shared key Ki and the selected signature algorithm f2, and then judges whether the calculated signature word is equal to the received digest word R2-R , if they are equal, the peer end is the legal party through the authentication, otherwise, the peer end is the illegal party.

Wherein, the digest word in step d is calculated according to the shared key K _i , the random number R2 generated by the receiving end, the random number R1 generated by the sending end and the selected signature algorithm; or based on the shared key K _i , the receiving end The random number R2 generated by the receiving end, the transmission key master_key to be sent, and the selected signature algorithm are calculated; or based on the shared key K _i , the random number R2 generated by the receiving end, the random number R1 generated by the sending end, It is calculated from the transmission key master_key to be sent and the selected signature algorithm.

In the above solution, the selected encryption algorithm is MD5 algorithm. The selected signature algorithm is MD5 algorithm. The sending end is a client or a server.

Therefore, in the method for safely sending transmission keys provided by the present invention, a key must be pre-shared between two communication entities, and the problem of secret key transmission between entities under the C-S framework can be solved by using the pre-shared key. The invention uses the random number and the shared key of both parties as the parameters of the signature algorithm, so that two communication entities can mutually confirm each other's identity, and can safely complete the process of transmitting the transmission key.

The present invention can take the process of confirming the identity of the other party as an optional process. If the identity confirmation of the other party is not performed, the processing flow of the secure transmission key of the present invention is simple and easy, and saves resources on the Server side; if the identity of the other party is confirmed, the present invention The invention combines the process of identity authentication and secure key transmission, so that the two processes of mutual identity authentication and secure key transmission work together to ensure the minimum transmission process under the condition of meeting the security requirements.

Description of drawings

Fig. 1 is a schematic flow chart of an implementation of the method of the present invention;

Fig. 2 is a schematic flow chart of another implementation of the method of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The basic idea of the present invention is: using the pre-shared key, one end securely transmits the owned transmission key master_key to the other end. Specifically, a key K _i is shared between the client and the server; the end to send the transmission key master_key generates a random number R, and uses the shared key K _i , the generated random number R, and the selected encryption Algorithm f1, signature algorithm f2, and the transmission key master_key to be sent, calculate the encryption key and digest word actually sent; the end receiving the transmission key bases on the received digest word, random number, encryption key and shared secret Key K _i , get the real transmission key master_key, and at the same time calculate the signature to verify the correctness of the information.

Here, the shared key K _i is usually securely stored in advance at the client end and the server end. Generally, the shared key is stored in a physical manner, and no one can read it after writing. The transmission key master_key to be sent can be obtained in various ways, such as: generated by a random number, or preset.

The selected encryption algorithm f1 and signature algorithm f2 can use any existing algorithm, and the client and the server should respectively retain at least one set of key generation algorithm and digital signature algorithm, and require both parties to have at least one set of the same key Generate algorithm and digital signature algorithm, client side and server side use the encryption algorithm and signature algorithm selected by both parties in advance to carry out the corresponding calculation.

The end to send the transmission key master_key may be the client end or the server end. The following only uses the client to send the transfer key master_key and the server to receive it as an example.

As shown in Figure 1, the method for safely sending the transmission key of the present invention includes the following steps:

Step 101: The client side wants to send its own transmission key master_key, then the client side first randomly generates a random number R1, and then uses the shared key K _i , the generated random number R1, and the selected encryption algorithm fl, according to the formula (1) Generate the encryption key Kc of the transmission key master_key:

Kc=f1(Ki, R1)master_key (1) and, according to the generated random number R1, the selected signature algorithm f2, and the calculated encryption key Kc, the client calculates the currently used Summary word Digt:

Digt＝f2(R1, Kc, master_key) (2)

Step 102: The client sends information {R1, Kc, Digt} carrying the random number R1, the encryption key Kc, and the digest word Digt to the server.

Step 103: After receiving the information, the server calculates the receiving key according to the formula (3) according to the shared key _Ki stored in itself, the received random number R1 and the encryption key Kc, and the selected encryption algorithm fl. The key rec_key, that is, the transmission key master_key:

rec_key=fl(Ki, R1)Kc=master_key (3) At the same time, using the received random number R1 and encryption key Kc, the selected signature algorithm f2 and the calculated receiving key rec_key, according to the formula (4 ) calculates the signature Rec_Digt used by itself:

  Rec_Digt＝f2(R1, Kc, rec_key) (4)

Step 104: The server judges whether the signature Rec_Digt calculated by itself is the same as the received digest Digt. If they are the same, that is, Rec_Digt=Digt, it means that the sent information is correct. If they are not the same, it means that the sent information is wrong, end the current process or notify the peer to resend.

In order to prevent possible copying attacks by illegal parties and realize mutual identity authentication between the two parties, steps 105 to 107 can be added, as shown in FIG. 2 .

Step 105: The server randomly generates a random number R2, and then calculates the digest word R2-R for authentication according to formula (5):

R2-R=f2(Ki, R2, R1, master_key) (5) Afterwards, the Server sends the information {R2, R2-R} to the Client.

Here, when calculating the summary word R2-R, the parameters R1 and master_key in formula (5) can be used in full, or only one of R1 and master_key can be selected.

Step 106: The client side verifies that R2-R is correct, then it considers that the transmission key master_key has been sent to the server side correctly. The specific authentication process is: the client calculates the signature word used by itself according to the received R2, the encryption key Kc generated by itself, the selected signature algorithm f2 and the transmission key master_key to be sent, and then judges the calculated Whether the signature word is equal to the received digest word R2-R, if they are equal, it means that the server side has correctly received the transmission key master_key, and it means that the server side is a legal party through the authentication; otherwise, it means that the server side is an illegal party, and the current process.

After the client confirms that the server has correctly received the transmission key master_key, it calculates the digest word R2_digt for authentication according to formula (6):

R2_digit=f2(Ki, R2) (6)

Step 107: the client end sends digital information with the digest word R2_digt to the server end, and the server end can determine that the first message is the message sent by the client end by verifying the received message with the digest word R2_digt, thereby realizing Identification of both parties. The specific verification process is: the server side calculates the signature word used by itself according to the random number R2 generated by itself, the shared key Ki and the selected signature algorithm f2, and then judges the calculated signature word and the received digest word R2 Whether -R is equal, if they are equal, it means that the client side is legal if the authentication is passed; otherwise, it means that the server side is an illegal party.

If the identity of both parties is not confirmed, the generation of R2 can be omitted on the server side, which can save resources on the server side.

In the above scheme, the value of the transmission key master_key can be updated at any time or periodically as needed, and the generation method is also set or generated by random numbers, etc., but the secure transmission process is exactly the same as the above steps, except that the The transfer key master_key values are different.

Taking the AC as the client end and the AP as the server end as an example to further illustrate, in this embodiment, the encryption algorithm f1 and the signature algorithm f2 selected between the AC and the AP are both MD5 algorithms, and the AC needs to send the transmission key master_key For AP, the implementation process is:

1) AC first randomly generates a random number R1, and then uses the shared key _Ki , the generated random number R1, and the selected encryption algorithm MD5 to generate the encryption key Kc of the transmission key master_key according to formula (7):

Kc=MD5(Ki, R1)master_key (7) And, AC calculates the digest word Digt according to the formula (8) according to the generated random number R1, the selected signature algorithm MD5, and the calculated encryption key Kc:

Digt＝MD5(R1, Kc, master_key) (8)

2) AC sends information {R1, Kc, Digt} carrying random number R1, encryption key Kc and digest word Digt to AP.

3) After receiving the information, the AP calculates the receiving key rec_key according to the formula (9) according to the shared key K _i stored by itself, the received random number R1 and the encryption key Kc, and the selected encryption algorithm MD5 , that is, transfer key master_key:

rec_key=MD5(Ki, R1)Kc=master_key (9) At the same time, using the received random number R1 and encryption key Kc, the selected signature algorithm f2 and the calculated receiving key rec_key, according to the formula (10 ) calculates its own signature Rec_Digt:

Rec_Digt＝MD5(R1, Kc, rec_key) (10)

4) The AP judges whether the signature Rec_Digt calculated by itself is the same as the received digest Digt. If they are the same, that is, Rec_Digt=Digt, it means that the information sent is correct. If they are not the same, it means that the sent information is wrong, end the current process or notify the peer to resend.

Then, the AP randomly generates a random number R2, and calculates the digest word R2-R for authentication according to the formula (11):

  R2-R＝MD5(Ki, R2, R1, master_key) (11)

5) AP sends the information {R2, R2-R} to AC, and AC verifies that R2-R is correct, then it can be considered that the master_key has been sent to AP correctly.

Afterwards, the AC calculates the digest word used for authentication, and sends the calculated signature word digital information to the AP, and the AP can confirm that the first message is sent by the AC by verifying the received message, so that identity confirmation can be realized , effectively preventing possible copying attacks by illegal parties.

Wherein, the verification at the AC or AP side is specifically: the AC or AP calculates the signature used by itself, and compares the calculated signature with the received digest, if they are the same, it means that the authentication is passed and the other party is a legal party; Otherwise, the authentication fails, and the other party is an illegal party.

In the above process, the AC can update the transmission key master_key value at any time or periodically, but the secure transmission process is exactly the same as the above steps.

The solutions described above are applicable to any C-S architecture. In a word, the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (7)

1. A method for securely sending a transmission key, in which the shared key K _i is respectively set at both communication parties in advance, characterized in that the method further comprises: a. The sender generates a random number R1, and then uses the generated random number R1, the shared key K _i , the transmission key master_key to be sent, and the selected encryption algorithm to generate an encryption key Kc, and calculates its own digest word ; b. The sending end sends the information carrying the digest word calculated in step a, the generated random number R1 and the encryption key Kc to the receiving end; c. After receiving the information sent in step b, the receiving end first obtains the transmission key master_key according to the shared key K _i , the received random number R1, the encryption key Kc and the selected encryption algorithm; and calculates its own Signature word, and then judge whether the calculated signature word is consistent with the received digest word, if yes, the received information is correct information; otherwise, the received information is wrong information. 2. The method according to claim 1, wherein the digest word in step a is calculated based on the random number R1, the encryption key Kc, the transmission key master_key to be sent and the selected signature algorithm. 3. The method according to claim 1, further comprising: d. The receiving end randomly generates a random number R2, and calculates the digest word R2-R for authentication, and then sends the generated random number R2 and the calculated digest word R2-R to the sending end; e. The sender calculates the signature used by itself based on the received random number R2, the encryption key Kc generated by itself, the selected signature algorithm f2, and the transmission key master_key to be sent, and then judges the calculated signature Whether it is equal to the received summary word R2-R, if they are equal, the peer end is the legal party through the authentication, otherwise, the peer end is the illegal party, and the current authentication process ends; f. The sending end calculates the digest word R2_digt for authentication according to the received random number R2, the shared key K _i and the selected signature algorithm f2, and sends the digest word R2_digt to the receiving end; g. The receiving end calculates the signature word used by itself according to the random number R2 generated by itself, the shared key Ki and the selected signature algorithm f2, and then judges whether the calculated signature word is equal to the received digest word R2-R , if they are equal, the peer end is the legal party through the authentication, otherwise, the peer end is the illegal party. 4. The method according to claim 3, wherein the digest word in step d is based on the shared key K _i , the random number R2 generated by the receiving end, the random number R1 generated by the sending end, and the selected signature algorithm Calculated; or calculated based on the shared key K _i , the random number R2 generated by the receiving end, the transmission key master_key to be sent, and the selected signature algorithm; or based on the shared key K _i , generated by the receiving end The random number R2 generated by the sender, the random number R1 generated by the sender, the transmission key master_key to be sent, and the selected signature algorithm are calculated. 5. The method according to claim 1, 2 or 3, characterized in that the selected encryption algorithm is MD5 algorithm. 6. The method according to claim 1, 2, 3 or 4, characterized in that the selected signature algorithm is MD5 algorithm. 7. The method according to claim 1, 3 or 4, characterized in that the sending end is a client or a server.

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