国密算法c#和Java互通

最近和外部系统对接，使用了国密算法，且我们这边是c#，对方是Java，折腾了一番后，把踩过的坑记录下来，有需要的可以参考。

一、密钥生成

我们这边生成密钥是用的bouncycastle.crypto库，一开始对方是用Java自带的加密库生成的密钥，结果是双方都使用不了对方的密钥，后来我们两边都统一使用bouncycastle.crypto库来生成密钥，问题解决。

二、密文格式

c#这边默认的密文格式是C1C2C3，而Java那边使用格式一开始是C1C3C2，导致加解密、加验签不成功，后来两边统一使用C1C2C3，问题解决。

总结：c#和Java国密互通，两边的密钥生成以及加解密、加验签都要统一使用bouncycastle.crypto库，密文格式也最好统一，如果不统一，需要C1C2C3和C1C2C3进行转换。

附加解密、加验签的代码

加密

cs 复制代码

public string EncryptM2(string message, string key)
        {
            X9ECParameters curve = ECNamedCurveTable.GetByName("sm2p256v1");
            ECPoint q = curve.Curve.DecodePoint(Base64.Decode(key));
            ECDomainParameters domain = new ECDomainParameters(curve);
            ECPublicKeyParameters pubk = new ECPublicKeyParameters("EC", q, domain);

            // 创建SM2加密器
            SM2Engine sm2Engine = new SM2Engine();
            sm2Engine.Init(true, new ParametersWithRandom(pubk, new SecureRandom()));

            byte[] dataBytes = Encoding.UTF8.GetBytes(message);
            byte[] encryptedData = sm2Engine.ProcessBlock(dataBytes, 0, dataBytes.Length);

            return Base64.ToBase64String(encryptedData);
        }

解密

cs 复制代码

public string DecryptM2(string message, string key)
        {
            X9ECParameters curve = ECNamedCurveTable.GetByName("sm2p256v1");
            ECDomainParameters domain = new ECDomainParameters(curve);
            BigInteger d = new BigInteger(1, Base64.Decode(key));
            ECPrivateKeyParameters prik = new ECPrivateKeyParameters(d, domain);

            // 创建SM2加密器
            SM2Engine sm2Engine = new SM2Engine();
            sm2Engine.Init(false, prik);

            byte[] encryptedData = Base64.Decode(message);
            byte[] decryptedData = sm2Engine.ProcessBlock(encryptedData, 0, encryptedData.Length);

            return Encoding.UTF8.GetString(decryptedData);
        }

加签

cs 复制代码

public string SignM2(string strPrivateKey, string strData)
        {
            byte[] messageBytes = System.Text.Encoding.UTF8.GetBytes(strData);

            X9ECParameters curve1 = ECNamedCurveTable.GetByName("sm2p256v1");
            ECDomainParameters domain1 = new ECDomainParameters(curve1);
            BigInteger d = new BigInteger(1, Base64.Decode(strPrivateKey));
            ECPrivateKeyParameters privKey = new ECPrivateKeyParameters(d, domain1);

            ISigner signer = SignerUtilities.GetSigner("SM3withSM2");
            signer.Init(true, new ParametersWithRandom(privKey, new SecureRandom()));
            signer.BlockUpdate(messageBytes, 0, messageBytes.Length);
            byte[] signature = signer.GenerateSignature();

            return Base64.ToBase64String(signature);
        }

验签

cs 复制代码

public bool verifySignM2(string strPublickey, string strData, string strSign)
        {
            byte[] messageBytes = System.Text.Encoding.UTF8.GetBytes(strData);
            byte[] signature = Base64.Decode(strSign);

            X9ECParameters curve = ECNamedCurveTable.GetByName("sm2p256v1");
            ECPoint q = curve.Curve.DecodePoint(Base64.Decode(strPublickey));
            ECDomainParameters domain = new ECDomainParameters(curve);
            ECPublicKeyParameters pubk = new ECPublicKeyParameters("EC", q, domain);

            ISigner signer = SignerUtilities.GetSigner("SM3withSM2");
            signer.Init(false, pubk);
            signer.BlockUpdate(messageBytes, 0, messageBytes.Length);
            bool isVerified = signer.VerifySignature(signature);
            return isVerified;
        }