OSCCA algorithm

Design objective

Bases on [national cryptography standard] (http://www.gmbz.org.cn/main/bzlb.html), FISCO has realized the national encryption and decryption, signature, verification, Hash algorithm, national cryptography SSL communication protocol, and integrated into the FISCO BCOS platform, and to achieve full support for commercial password identified by the National Cryptographic Bureau.

The national cryptography version of FISCO BCOS replaces the cryptographic algorithms of the underlying modules such as transaction signature verification, p2p network connection, node connection, and data disk encryption with the national cryptography algorithm.

The different features between national cryptography version of FISCO BCOS and the standard version are as follows:

	standard FISCO BCOS	national cryptography FISCO BCOS
SSL connect	Openssl TLSv1.2 protocol	national cryptography TLSv1.1 protocol
signature verification	ECDSA signature algorithm	SM2 signature algorithm
Message digest algorithm	SHA-256 SHA-3	SM3 message digest algorithm
Disk encryption algorithm	AES-256 encryption algorithm	SM4 encryption algorithm
Certificate mode	OpenSSL certificate mode	National cryptography double certificate mode
Contract compiler	Ethereum solidity compiler	National cryptography solidity compiler

(Note: National cryptography algorithms SM2, SM3, SM4 are developed based on [national cryptography standards] (http://www.gmbz.org.cn/main/bzlb.html))

System framework

The overall framework of the system is shown below:

National cryptography SSL 1.1 establish process

The authentication among the nodes of national cryptography FISCO BCOS selects the ECDHE_SM4_SM3 cipher suite of the national cryptography SSL 1.1 for the establishment of SSL connect. The differences are shown in the following table:

	OpenSSL	National cryptography SSL
Cipher suite	Adopts ECDH, RSA, SHA-256, AES256 and other cryptographic algorithms	Adopts national cryptography
PRF algorithm	SHA-256	SM3
Key exchange method	Transmits elliptic curve parameters and the signature of current message	Current message signature and encryption certificate
Certificate mode	OpenSSL certificate mode	National cryptography double certificate modes, encryption certificate and signature certificate.

Data structure difference

The difference in data structure between the national cryptography version and the standard version of FISCO BCOS is as follows:

Algorithm type	Standard FISCO BCOS	National cryptography FISCO BCOS
signature	ECDSA (Public and private key length: 512 bits, 256 bits)	SM2 (Public and private key length: 512 bits, 256 bits)
hash	SHA3 (Hash string length: 256 bits)	SM3 (Hash string length: 256 bits)
Symmetric encryption and decryption	AES (Encryption key length: 256 bits)	SM4 (Symmetric key length: 128 bits)
Transaction length	520bits(identifier is 8bits, signature length is 512bits)	1024bits(128 bytes, public key is 512bits, signature length is 512bits)