CN108242997B - Method and device for secure communication - Google Patents

Abstract

The invention relates to the field of information security, and discloses a method and device for secure communication. In the embodiment of the present invention, verify whether the public key of the CA is complete and whether the digital signature of the CA is valid; if the public key of the CA is complete and the digital signature of the CA is valid, the CA and the TA generate a symmetric key through three-way handshake, and according to the symmetric key key for encrypted communication. In the embodiment of the present invention, by verifying the public key and digital signature of the CA, the tampered or counterfeited CA can be effectively identified. The CA and the TA generate a symmetric key through three-way handshake, and perform encrypted communication according to the symmetric key, ensuring that The confidentiality and integrity of the communication content effectively prevent attackers from stealing sensitive data or destroying the communication system.

Description

Method and device for secure communication

technical field

The present invention relates to the field of information security, in particular to a method and device for secure communication.

Background technique

In the terminal equipment system that introduces TEE (Trusted Execution Environment), including TEE and REE (Rich Execution Environment, rich execution environment) two subsystems, TEE is responsible for processing transactions that require higher security protection, such as secret keys Storage, encryption and decryption, fingerprint recognition, etc., REE is a common operating system, such as Android Android system, iOS Apple system, etc., running on the REE operating system CA (Client Application, customer application) and TA (Trusted Application, trusted application) applications) communicate through shared memory, as shown in FIG. 1 , the rich execution environment 11 includes a client application 111 and a rich execution environment operating system 112, and the trusted execution environment 13 includes a trusted application 131 and a trusted execution environment operating system 132, The client application 111 communicates with the trusted application 131 through the shared memory 12. The existing technical solutions generally protect the integrity or confidentiality of the TEE operating system and the TA, and some solutions also protect the integrity of the REE operating system. .

However, in the process of implementing the present invention, the inventor of the present application found that, for CA, the existing solutions either have no protection, or the protection is not strong enough, for example, when CA adopts the form of Android APK (Android Package, Android installation package) , CA APK can be signed, but Android uses a self-signed method. The signed certificate used in this self-signed method is not issued by an authoritative certification authority, but generated by the developer himself. Since the self-signed certificate cannot be used for authentication The root certificate of the organization is verified, so an additional mechanism must be added to protect the integrity of the public key in the self-signed certificate, but Android does not have a relevant mechanism, so the integrity of the CA cannot be guaranteed in essence, that is to say, the CA may has been tampered with or counterfeited without the system being able to detect it. Attackers can pose a threat to the TEE system by tampering with or counterfeiting the CA, such as stealing sensitive data and disrupting the normal operation of the TEE system. In addition, the existing scheme does not protect the confidentiality and integrity of the shared memory communication between the CA and the TA, and the TEE specification maker GlobalPlatform (Global Platform International Standards Organization) has not released relevant specifications, so that attackers can pass the REE system on the system. Malware steals or modifies the content of communications, thereby stealing sensitive data or disrupting the normal operation of TEE systems.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a method and device for secure communication. By verifying the integrity of the CA's public key and the validity of the CA's digital signature, it can effectively identify the tampered or counterfeited CA, CA The symmetric key is generated through three-way handshake with the TA, and encrypted communication is performed according to the symmetric key, which ensures the confidentiality and integrity of the communication content, and effectively prevents attackers from stealing sensitive data or destroying the communication system.

In order to solve the above technical problems, embodiments of the present invention provide a method for secure communication, including:

Verify that the CA's public key is complete and the CA's digital signature is valid;

If the public key of the CA is complete and the digital signature of the CA is valid, the CA and the TA generate a symmetric key through a three-way handshake, and perform encrypted communication according to the symmetric key.

Embodiments of the present invention also provide a safety communication device, comprising:

A verification module for verifying whether the public key of the CA is complete and whether the digital signature of the CA is valid;

generating a symmetric key module for generating a symmetric key between the CA and the TA through a three-way handshake after verifying that the CA's public key is complete and the CA's digital signature is valid;

A communication module, configured to perform encrypted communication between the CA and the TA according to the symmetric key.

Compared with the prior art, the embodiment of the present invention can effectively identify the tampered or counterfeited CA by verifying the integrity of the public key of the CA and the validity of the digital signature, and the CA and the TA generate a symmetric key through three-way handshake. encrypted communication according to the symmetric key, which ensures the confidentiality and integrity of the communication content, and effectively prevents attackers from stealing sensitive data or destroying the communication system.

In addition, the verifying whether the public key of the CA is complete and whether the digital signature of the CA is valid specifically includes: the trusted execution environment operating system detects whether the first digest of the public key of the CA is stored in the TA. The second digest is the same as the second digest of the public key, wherein the second digest is the second digest of the public key generated according to a preset digest algorithm; if the first digest is the same as the second digest, the rich execution environment operating system According to the public key, verify whether the digital signature of the CA is valid; if the digital signature of the CA is valid, the CA is complete. By detecting whether the first digest is the same as the second digest, the tampered or counterfeited CA public key can be effectively identified, and by verifying the validity of the CA's digital signature, the tampered or counterfeited CA can be effectively identified, thus ensuring that the CA completeness.

In addition, before the trusted execution environment operating system detects whether the first digest of the public key of the CA is the same as the second digest stored in the TA, the method further includes: the rich execution environment operating system according to the predetermined A digest algorithm is provided, the first digest is calculated, and the first digest is sent to the trusted execution environment operating system. It is convenient for the operating system of the trusted execution environment to effectively identify the public key of the CA that is counterfeited or tampered with in the communication process.

In addition, the CA and the TA generate a symmetric key through a three-way handshake, which specifically includes: the CA sends the generated first random number and the algorithm list of the symmetric encryption algorithm and the message authentication code algorithm; the TA sends the selected The identifier of the algorithm in the algorithm list, the generated public key of the RSA public-private key pair, and the generated second random number; the CA sends the third random number encrypted according to the RSA public key; the CA and the TA are respectively The symmetric key is generated according to the first random number, the second random number and the third random number. CA and TA generate a symmetric key through three-way handshake, which ensures the security of the key, thereby ensuring the confidentiality and integrity of the communication content, and effectively preventing attackers from stealing sensitive data or damaging the communication system.

Description of drawings

1 is a schematic diagram of the interaction between a trusted execution environment and a rich execution environment in the prior art;

2 is a flowchart of a method for secure communication according to the first embodiment of the present invention;

3 is a flowchart of a method for secure communication according to a second embodiment of the present invention;

4 is a schematic structural diagram of a safety communication device according to a third embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a safety communication device according to a fourth embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, each embodiment of the present invention will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art will appreciate that, in the various embodiments of the present invention, many technical details are set forth in order for the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be realized.

A first embodiment of the present invention relates to a method for secure communication. The specific process is shown in Figure 2.

In step 201, verify whether the public key of the client application is complete and whether the digital signature is valid. If the public key of the client application is complete and the digital signature of the client application is valid, step 202 is executed, otherwise, the end.

Specifically, verify whether the public key of the client application CA is complete and whether the digital signature of the CA is valid. If the public key of the CA is complete and the digital signature of the CA is valid, it means that the CA has not been tampered or counterfeited by the attacker, and proceed to step 202 , the client application and the trusted application generate a symmetric key through three-way handshake, otherwise, it means that the CA has been tampered or counterfeited by the attacker, and the communication will be terminated immediately, thereby effectively identifying the tampered or counterfeited CA.

In step 202, the client application and the trusted application generate a symmetric key through three-way handshake.

Specifically, when the CA is not tampered with or counterfeited by the attacker, the client application CA and the trusted application TA generate a symmetric key through a three-way handshake process, which ensures the security of the key, and thus ensures the confidentiality and integrity of the communication content. Integrity, effectively preventing attackers from stealing sensitive data or destroying communication systems.

In step 203, encrypted communication is performed according to the symmetric key.

Specifically, when the sender sends a letter to the receiver, it first encrypts the content to be sent according to the symmetric key, and then sends it to the receiver through the shared memory. When the receiver replies to the sender, it also encrypts the content to be sent according to the symmetric key. Encrypted, and then sent to the sender through shared memory, thus effectively preventing attackers from stealing sensitive data.

Compared with the prior art, in this embodiment, by verifying the integrity of the public key of the CA and the validity of the digital signature, the CA that has been tampered with or counterfeited can be effectively identified, and the CA and the TA generate a symmetry through a three-way handshake. The key is encrypted and the communication is encrypted according to the symmetric key, which ensures the confidentiality and integrity of the communication content, and effectively prevents attackers from stealing sensitive data or destroying the communication system.

A second embodiment of the present invention relates to a method for secure communication. The second embodiment is further improved on the basis of the first embodiment. The main improvement lies in that: in the second embodiment of the present invention, not only the process of verifying the public key and digital signature of the CA is given, but also The specific process of CA and TA generating a symmetric key through three-way handshake is also given, as shown in Figure 3.

In step 301, the public key of the client application and the digital signature generated according to the private key of the client application are saved.

Specifically, the CA stores the public key and the digital signature generated according to the CA's private key, wherein the public key and the private key are a public-private key pair generated according to a preset digital signature algorithm, that is to say, the digital signature will be generated according to the preset digital signature algorithm. The generated public key of the CA asymmetric public-private key pair, and the digital signature generated by the CA based on the private key of the asymmetric public-private key pair, are stored in the CA's software package, wherein the preset digital signature algorithm may be an RSA encryption algorithm, DSA (Digital Signature Algorithm, digital signature algorithm) or ECDSA (elliptic curve digital signature algorithm, elliptic curve digital signature algorithm).

In step 302, a first digest of the client application's public key is calculated.

Specifically, the rich execution environment operating system calculates the first digest of the public key of the client application according to the preset digest algorithm, that is to say, the rich execution environment operating system REE OS calculates the CA public key in the CA software package according to the preset digest algorithm The digest of the key is recorded as the first digest, wherein the preset digest algorithm can be MD5 (Message Digest Algorithm 5, Message Digest Algorithm 5), SHA1 (Secure Hash Algorithm, Secure Hash Algorithm 1), SHA224 (Secure HashAlgorithm 224, Secure Hash Algorithm 224), SHA256 (Secure Hash Algorithm 256, Secure Hash Algorithm 256), SHA384 (Secure Hash Algorithm 384, Secure Hash Algorithm 384) or SHA512 (Secure HashAlgorithm 512, Secure Hash Algorithm 512).

In step 303, the first digest is sent to the trusted execution environment operating system.

Specifically, the REE OS sends the calculated first digest to the trusted execution environment operating system TEE OS.

In step 304, it is detected whether the first digest is the same as the second digest stored in the trusted application, if it is the same, then step 305 is executed, otherwise, the process ends.

Specifically, the trusted execution environment operating system detects whether the first digest of the CA's public key is the same as the second digest stored in the TA, where the second digest is the second digest of the public key generated according to a preset digest algorithm, That is to say, after TEEOS receives the first digest sent by REE OS, it first reads the digest of the CA public key saved in the TA software package, that is, the second digest, and then checks whether the first digest is the same as the second digest. , if the first digest is the same as the second digest, it means that the CA's public key is complete, indicating that the CA has not been tampered with or counterfeited by the attacker, then step 305 is executed, otherwise, it means that the public key of the CA has been tampered with or counterfeited by the attacker, End the communication directly.

In step 305, verify whether the digital signature of the client application is valid, if it is valid, execute step 306, otherwise end.

Specifically, when the first digest is the same as the second digest, the rich execution environment operating system further verifies whether the digital signature of the CA is valid according to the CA public key. The validity verification of the digital signature, wherein the digital signature verification process is the same as the data signature verification process in the prior art, and will not be repeated here, and the digital signature verification algorithm is consistent with the digital signature algorithm, which can be RSA, DSA or ECDSA, If the digital signature is valid, that is, the verification of the digital signature is passed, indicating that the CA has not been tampered with or counterfeited by the attacker, load and run the CA, and execute step 306; otherwise, directly end the communication without loading the running CA, thereby effectively identifying the tampered CA. , which ensures the integrity of the CA.

In step 306, the client application sends the generated first random number and the algorithm list.

Specifically, the client application sends the generated first random number and the algorithm list of the symmetric encryption algorithm and message authentication code algorithm supported by the CA, wherein the symmetric encryption algorithm can be DES (Data Encryption Standard, data encryption standard), 3DES (Triple Data Encryption Algorithm, triple data encryption algorithm) or AES (Advanced Encryption Standard, Advanced Encryption Standard), etc. The message authentication code algorithm can be HMAC (Hash-based Message Authentication Code, hash-based message authentication code), CBC-MAC (Cipher BlockChaining Message Authentication Code, cipher block chaining message authentication code) or CMAC (Cipher-based Message Authentication Code, password-based message authentication code) ^[ .

In step 307, the trusted application sends the algorithm identifier, the public key and the generated second random number.

Specifically, the TA sends the identifier of the algorithm in the selected algorithm list, the generated public key of the RSA public-private key pair, and the generated second random number, that is, the TA selects the symmetric encryption algorithm and the message authentication code algorithm used by both parties, Generate the RSA public-private key pair and the second random number, and then output the algorithm identifier, the RSA public key pair and the second random number to the CA.

In step 308, the client application sends the encrypted third random number.

Specifically, the CA sends the third random number encrypted according to the RSA public key, that is, the CA regenerates a third random number, and uses the TA's RSA public key to encrypt the third random number, and then encrypts the encrypted third random number. output to TA.

In step 309, the client application and the trusted application generate a symmetric key.

Specifically, CA and TA generate symmetric keys according to the first random number, the second random number, and the third random number, respectively, where TA decrypts the third random number with its own RSA private key, so that both CA and TA have There are three random numbers, namely the first random number, the second random number and the third random number, CA and TA use the same rules to generate keys, such as XOR rules, digest rules and so on.

In step 310, encrypted communication is performed according to the symmetric key.

Specifically, TA and CA conduct encrypted communication based on the same symmetric key and algorithm. The output party first encrypts the message, then calculates the message authentication code for the ciphertext, and then outputs the message authentication code and ciphertext message through the shared memory. The receiver first calculates the message authentication code for the received ciphertext message, and then compares and verifies it with the received message authentication code. If the two are different, it indicates that the message integrity is destroyed. , which ensures the confidentiality and integrity of the communication content and effectively prevents attackers from stealing sensitive data or destroying the communication system.

The embodiments of the present invention not only provide a specific process for verifying the CA's public key and digital signature, but also provide a specific process for CA and TA to generate a symmetric key through three-way handshake, which is convenient for technical personnel to implement the algorithm in practical applications.

The step division of the above various methods is only for the purpose of describing clearly. During implementation, it can be combined into one step or some steps can be split and decomposed into multiple steps, as long as they contain the same logical relationship, they are all within the protection scope of this patent. ;Adding insignificant modifications to the algorithm or process or introducing insignificant designs, but not changing the core design of the algorithm and process are all within the scope of protection of this patent.

The third embodiment of the present invention relates to a secure communication device, as shown in FIG. 4 , including: a verification module 41 , a symmetric key generation module 42 and a communication module 43 .

The verification module 41 is used to verify whether the public key of the CA is complete and whether the digital signature of the CA is valid.

The generating symmetric key module 42 is configured to generate a symmetric key between the CA and the TA through a three-way handshake after verifying that the public key of the CA is complete and the digital signature of the CA is valid.

The communication module 43 is configured to perform encrypted communication between the CA and the TA according to the symmetric key.

It is not difficult to find that this embodiment is a system example corresponding to the first embodiment, and this embodiment can be implemented in cooperation with the first embodiment. The relevant technical details mentioned in the first embodiment are still valid in this embodiment, and are not repeated here in order to reduce repetition. Correspondingly, the related technical details mentioned in this embodiment can also be applied to the first embodiment.

It is worth mentioning that each module involved in this embodiment is a logical module. In practical applications, a logical unit may be a physical unit, a part of a physical unit, or multiple physical units. A composite implementation of the unit. In addition, in order to highlight the innovative part of the present invention, this embodiment does not introduce units that are not closely related to solving the technical problem proposed by the present invention, but this does not mean that there are no other units in this embodiment.

A fourth embodiment of the present invention relates to a safety communication device. The fourth embodiment is further improved on the basis of the third embodiment. The main improvement lies in that: in the fourth embodiment of the present invention, not only the verification module 41, the symmetric key generation module 42 and the communication module 43 are included, but also the It includes: a CA storage module 44, a first digest calculation module 45, and a first digest sending module 46, wherein the detection module 41 specifically includes: a digest detection sub-module 411, a digital signature detection sub-module 412 and a determination sub-module 413, which generate a symmetric encryption module. The key module 42 specifically includes: a first CA sending submodule 421 , a TA sending submodule 422 , a second CA sending submodule 423 , a CA key generating submodule 424 , and a TA key generating submodule 425 , as shown in FIG. 5 .

The CA storage module 44 is used for the CA to store the public key and the digital signature generated according to the private key of the CA, wherein the public key and the private key are a public-private key pair generated according to a preset digital signature algorithm.

The first digest calculation module 45 is used for the rich execution environment operating system to calculate the first digest according to a preset digest algorithm.

The first digest sending module 46 is configured to send the first digest to the trusted execution environment operating system.

The verification module 41 is used to verify whether the public key of the CA is complete and whether the digital signature of the CA is valid.

The digest detection sub-module 411 is used for the trusted execution environment operating system to detect whether the first digest of the public key of the CA is the same as the second digest stored in the TA.

The digital signature verification sub-module 412 is used for, when the first digest is the same as the second digest, the rich execution environment operating system to verify whether the digital signature of the CA is valid according to the public key.

The determining sub-module 413 is used for determining that the CA is complete when the digital signature verification of the CA is valid.

The generating symmetric key module 42 is configured to generate a symmetric key between the CA and the TA through a three-way handshake after verifying that the public key of the CA is complete and the digital signature of the CA is valid.

The first CA sending sub-module 421 is used for the CA to send the generated first random number and the algorithm list of the symmetric encryption algorithm and the message authentication code algorithm.

The TA sending sub-module 422 is used for the TA to send the identifier of the algorithm in the selected algorithm list, the generated public key of the RSA public-private key pair, and the generated second random number.

The second CA sending sub-module 423 is used for the CA to send the third random number encrypted according to the RSA public key.

Specifically, in practical applications, the first CA sending sub-module 421 and the second CA sending sub-module 423 may be combined together, or may be separated.

The CA key generation sub-module 424 is configured to generate the CA key of the symmetric key according to the first random number, the second random number and the third random number.

The TA key generation sub-module 425 is configured to generate the TA key of the symmetric key according to the first random number, the second random number and the third random number.

The communication module 43 is configured to perform encrypted communication between the CA and the TA according to the symmetric key.

Since the second embodiment corresponds to the present embodiment, the present embodiment can be implemented in cooperation with the second embodiment. The relevant technical details mentioned in the second embodiment are still valid in this embodiment, and the technical effects that can be achieved in the second embodiment can also be achieved in this embodiment, and in order to reduce repetition, they will not be repeated here. Correspondingly, the related technical details mentioned in this embodiment can also be applied to the second embodiment.

Those skilled in the art can understand that all or part of the steps in the method of the above embodiments can be completed by instructing the relevant hardware through a program. The program is stored in a storage medium and includes several instructions to make a device (which may be a single-chip microcomputer) , chip, etc.) or a processor (processor) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: flash memory (Flash Memory), U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and other various A medium on which program code can be stored.

Those of ordinary skill in the art can understand that the above-mentioned embodiments are specific examples for realizing the present invention, and in practical applications, various changes in form and details can be made without departing from the spirit and the spirit of the present invention. scope.

Claims (4)

1. A method for secure communication, wherein a client application CA applied to a same terminal device and a trusted application TA corresponding to the CA comprise:

verifying whether the public key of the CA is complete and whether the digital signature of the CA is valid specifically includes: the CA stores a public key and a digital signature generated according to a private key of the CA, wherein the public key and the private key are a public and private key pair generated according to a preset digital signature algorithm; the rich execution environment operating system calculates a first abstract of a public key of a CA (conditional access) according to a preset abstract algorithm, and sends the first abstract of the public key of the CA to the trusted execution environment operating system; the trusted execution environment operating system detects whether a first abstract of a public key of the CA is the same as a second abstract stored in the TA, wherein the second abstract is the second abstract of the public key generated according to the preset abstract algorithm; if the first abstract is the same as the second abstract, the rich execution environment operating system verifies whether the digital signature of the CA is valid according to the public key; if the digital signature of the CA is valid, the CA is complete;

and if the public key of the CA is complete and the digital signature of the CA is valid, the CA and the TA generate a symmetric key through three-way handshake, and carry out encryption communication according to the symmetric key.

2. The method according to claim 1, wherein the CA and the TA generate the symmetric key through three-way handshake, specifically comprising:

the CA sends the generated first random number and an algorithm list of a symmetric encryption algorithm and a message authentication code algorithm;

the TA sends the selected identifier of the algorithm in the algorithm list, the generated public key of the RSA public and private key pair and the generated second random number;

the CA sends a third random number encrypted according to the RSA public key;

and the CA and the TA respectively generate the symmetric key according to the first random number, the second random number and the third random number.

3. A secure communication device, wherein a client application CA and a trusted application TA corresponding to the CA are applied to the same terminal device, the secure communication device comprising:

the verification module is used for verifying whether the public key of the CA is complete and whether the digital signature of the CA is valid;

the symmetric key generation module is used for generating a symmetric key of the CA and the TA through three-way handshake after verifying that the public key of the CA is complete and the digital signature of the CA is valid;

a communication module, configured to perform encrypted communication between the CA and the TA according to the symmetric key;

wherein the verification module specifically comprises: the device comprises a digest detection submodule, a digital signature verification submodule and a determination submodule;

the digest detection submodule is used for a trusted execution environment operating system to detect whether a first digest of a public key of the CA is the same as a second digest stored in the TA;

the digital signature verification submodule is used for verifying whether the digital signature of the CA is valid or not according to the public key when the first abstract is the same as the second abstract by the rich execution environment operating system;

the determining submodule is used for determining that the CA is complete when the digital signature of the CA is verified to be valid;

the apparatus further comprises: the system comprises a first abstract calculation module, a first abstract sending module and a CA storage module;

the first abstract calculation module is used for calculating a first abstract of the public key of the CA by the rich execution environment operating system according to a preset abstract algorithm;

the first digest sending module is configured to send a first digest of the public key of the CA to the trusted execution environment operating system;

the CA storage module is used for storing the public key and a digital signature generated according to a private key of the CA by the CA, wherein the public key and the private key are a public and private key pair generated according to a preset digital signature algorithm.

4. The secure communications device of claim 3, wherein the module for generating a symmetric key specifically comprises: the first CA sending submodule, the TA sending submodule, the second CA sending submodule, the CA key generating submodule and the TA key generating submodule;

the first CA sending submodule is used for the CA to send the generated first random number, the algorithm list of the symmetric encryption algorithm and the message authentication code algorithm;

the TA sending submodule is used for sending the selected identifier of the algorithm in the algorithm list, the generated public key of the RSA public and private key pair and the generated second random number by the TA;

the second CA sending submodule is used for sending a third random number encrypted according to the RSA public key by the CA;

the CA key generation submodule is used for generating a CA key of the symmetric key according to the first random number, the second random number and the third random number;

and the TA key generation submodule is used for generating the TA key of the symmetric key according to the first random number, the second random number and the third random number.

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