sm2withsm3签名算法

### 使用 SM2 和 SM3 实现数字签名算法 #### 数字签名概述 数字签名是一种用于确认数据的真实性和完整性的重要机制。SM2 是一种基于椭圆曲线密码学的非对称加密标准，而 SM3 则是中国国家商用密码管理局颁布的一种哈希函数标准。 #### 签名生成过程 为了创建一个安全有效的数字签名，通常会先利用散列函数处理原始消息得到固定长度的消息摘要，再通过私钥对该摘要进行加密形成最终的签名。具体到 SM2 和 SM3 的组合使用上： 1. 对待签发的数据 `msg` 应用 SM3 散列算法获取其摘要值 `z=Hash(msg)`[^1]。 2. 将上述获得的摘要作为输入传递给 SM2 算法中的签名部分，依据发送方持有的私钥完成实际签名操作 `(r,s)=Sign(z,privKey)`。 ```csharp using System; using Org.BouncyCastle.Crypto.Parameters; // 假设已安装 Bouncy Castle NuGet 包 using Org.BouncyCastle.Math; public class Sm2Sm3Signature { public static Tuple<BigInteger,BigInteger> Sign(string messageText, ECPrivateKeyParameters privateKey){ byte[] msgBytes = Encoding.UTF8.GetBytes(messageText); // Step 1: Compute the hash of the message using SM3. var sm3Digest = new Org.BouncyCastle.Crypto.Digests.SM3Digest(); byte[] hashedMessage = new byte[sm3Digest.GetDigestSize()]; sm3Digest.BlockUpdate(msgBytes, 0, msgBytes.Length); sm3Digest.DoFinal(hashedMessage, 0); // Convert to BigInteger as required by some libraries for signing operations. BigInteger z = new BigInteger(1,hashedMessage); // Step 2: Perform signature with private key and computed hash value. // Note this is a simplified representation assuming existence of such method within library used. return GenerateSignatureWithPrivatekey(privateKey,z); } } ``` #### 签名验证过程 接收者接收到带有签名的信息后，需执行如下步骤来检验该签名是否合法： 1. 同样采用 SM3 函数重新计算所收信息的内容摘要 `z'=Hash(receivedMsg)`[^3]。 2. 调用 SM2 中定义的方法并传入对方提供的公钥以及之前求得的新鲜摘要来进行校验工作 `Verify((r',s'),pubKey,z')`。 ```csharp // Assuming we have received r, s values from sender along with their public key parameters. public static bool Verify(Tuple<BigInteger,BigInteger> signTuple,ECPublicKeyParameters publicKey,string receivedMessage){ byte[] recvdMsgBytes = Encoding.UTF8.GetBytes(receivedMessage); var sm3DigestForVerification = new Org.BouncyCastle.Crypto.Digests.SM3Digest(); byte[] recalculatedHashedMessage = new byte[sm3DigestForVerification.GetDigestSize()]; sm3DigestForVerification.BlockUpdate(recvdMsgBytes, 0, recvdMsgBytes.Length); sm3DigestForVerification.DoFinal(recalculatedHashedMessage, 0); BigInteger rzPrime = new BigInteger(1,recalculatedHashedMessage); // Simplified call to verification function provided by cryptographic library being utilized. return ValidateSignature(signTuple.Item1,signTuple.Item2,publicKey,rzPrime); } ```