密钥协商只要知道步骤,再利用BouncyCastle实现的SM2KeyExchange类来按步骤写,就不难,我们先看步骤:

步骤一：
用户A为发起方，生成随机SM2密钥对，初始化密钥协商
用户A将公钥发送给用户B：0256fbc5499c97e4b3e0b242c78e97f7792b416cbdec84357a7d1e9f52f133982d
用户A将随机公钥发送给用户B：03953b219b0bd5b4a7fc7e56b1a4c7c9623a6ef8fce63535aca2a421be541f2bdc
用户A将自身USERID发送给用户B：31323334353637383132333435363738

步骤二：
用户B为响应方，生成随机SM2密钥对，初始化密钥协商
用户B使用用户A的公钥、随机公钥、USERID来计算密钥及SB
用户B计算的密钥：d454c84c592dda5da97ce0d9b506ab7e

用户B将公钥发送给用户A：029754599adf0d8f71e8cc6bd7c284f0b1e4750c4cb1409d42fe0e4c5690cff705
用户B将随机公钥发送给用户A：021fdfb35f7fb1de5d65b54bd623f3caea0ff8da5e3bc716b6e4342080d8f540f4
用户B将自身USERID发送给用户A：31323334353637383837363534333231
用户B将SB发送给用户A：2b83339652e3706fc5ee2c9c2b3863aa0ee2ca8009f8a780a4da65426c8d3ffb

步骤三：
用户A使用用户B的公钥、随机公钥、USERID来计算密钥及SA，并校验S1==SB
用户A计算的密钥：d454c84c592dda5da97ce0d9b506ab7e

用户A将SA发送给用户B：55449f1296f05c02837e9b6f7be26494327c1548e6de594da3e901186598335f

步骤四：
用户B校验S2==SA

这里不讲原理性的东西,可以去参照规范文档或C语言相关部分,以下是上述步骤的相应代码:

@Test
public void testExchange() {
    // 获取国密曲线
    X9ECParameters gmParameters = GMNamedCurves.getByName("sm2p256v1");
    // 构造Domain参数
    ECDomainParameters gmDomainParameters = new ECDomainParameters(gmParameters.getCurve(),
            gmParameters.getG(), gmParameters.getN());

    try {
        // SM2KeyExchangePrivateParameters及SM2KeyExchangePublicParameters中ephemeral开头的为随机公私钥
        // 知道这个区别，用BC的SM2KeyExchange来实现SM2密钥协商就简单了

        // 用户A
        ECPrivateKeyParameters userAPrivK = new ECPrivateKeyParameters(
                new BigInteger(1, Hex.decodeStrict("a09a8cdea50ce62e172c6aab13d1c74cc7b6b3b1f76b3789bfde4db1c4a95d06")),
                gmDomainParameters);
        ECPublicKeyParameters userAPubK = new ECPublicKeyParameters(gmDomainParameters.getCurve().decodePoint(
                Hex.decode("0256fbc5499c97e4b3e0b242c78e97f7792b416cbdec84357a7d1e9f52f133982d")), gmDomainParameters);

        // FIXME 生产应随机生成
        ECPrivateKeyParameters userARandPrivK = new ECPrivateKeyParameters(
                new BigInteger(1, Hex.decodeStrict("0027ebfb3086a7c993134b3fd7abbc911c561558a0cde7ca5fc230c825025cd3")),
                gmDomainParameters);
        ECPublicKeyParameters userARandPubK = new ECPublicKeyParameters(gmDomainParameters.getCurve().decodePoint(
                Hex.decode("03953b219b0bd5b4a7fc7e56b1a4c7c9623a6ef8fce63535aca2a421be541f2bdc")), gmDomainParameters);

        byte[] userAId = Hex.decodeStrict("31323334353637383132333435363738");

        // 用户A为发起方
        SM2KeyExchangePrivateParameters userAPrivParams = new SM2KeyExchangePrivateParameters(true, userAPrivK, userARandPrivK);
        ParametersWithID userAPrivIdParams = new ParametersWithID(userAPrivParams, userAId);

        SM2KeyExchange userAKeyExchange = new SM2KeyExchange();
        userAKeyExchange.init(userAPrivIdParams);

        System.out.println("步骤一：");
        System.out.println("用户A为发起方，生成随机SM2密钥对，初始化密钥协商");
        System.out.println("用户A将公钥发送给用户B：0256fbc5499c97e4b3e0b242c78e97f7792b416cbdec84357a7d1e9f52f133982d");
        System.out.println("用户A将随机公钥发送给用户B：03953b219b0bd5b4a7fc7e56b1a4c7c9623a6ef8fce63535aca2a421be541f2bdc");
        System.out.println("用户A将自身USERID发送给用户B：31323334353637383132333435363738");
        System.out.println();

        // 用户B
        ECPrivateKeyParameters userBPrivK = new ECPrivateKeyParameters(
                new BigInteger(1, Hex.decodeStrict("1baa9c7d28281970da2502730abf275d0300ec410390c3d7c2611daa3d9b9892")),
                gmDomainParameters);
        ECPublicKeyParameters userBPubK = new ECPublicKeyParameters(gmDomainParameters.getCurve().decodePoint(
                Hex.decode("029754599adf0d8f71e8cc6bd7c284f0b1e4750c4cb1409d42fe0e4c5690cff705")), gmDomainParameters);

        // FIXME 生产应随机生成
        ECPrivateKeyParameters userBRandPrivK = new ECPrivateKeyParameters(
                new BigInteger(1, Hex.decodeStrict("eed5f1af1daf647f31eebbb4cea58d16bf7716d085c5ef79c543c645c8c44654")),
                gmDomainParameters);
        ECPublicKeyParameters userBRandPubK = new ECPublicKeyParameters(gmDomainParameters.getCurve().decodePoint(
                Hex.decode("021fdfb35f7fb1de5d65b54bd623f3caea0ff8da5e3bc716b6e4342080d8f540f4")), gmDomainParameters);

        byte[] userBId = Hex.decodeStrict("31323334353637383837363534333231");

        // 用户B为响应方
        SM2KeyExchangePrivateParameters userBPrivParams = new SM2KeyExchangePrivateParameters(false, userBPrivK, userBRandPrivK);
        ParametersWithID userBPrivIdParams = new ParametersWithID(userBPrivParams, userBId);

        SM2KeyExchange userBKeyExchange = new SM2KeyExchange();
        userBKeyExchange.init(userBPrivIdParams);

        System.out.println("步骤二：");
        System.out.println("用户B为响应方，生成随机SM2密钥对，初始化密钥协商");

        System.out.println("用户B使用用户A的公钥、随机公钥、USERID来计算密钥及SB");
        // 用A的公钥、随机公钥、USERID生成参数
        // 我这里直接拿A的变量用了，实际要用传过来的公钥、随机公钥、USERID创建对应的userAPubK,、userARandPubK、userAId
        SM2KeyExchangePublicParameters userAPubParams = new SM2KeyExchangePublicParameters(userAPubK, userARandPubK);
        ParametersWithID userAPubIdParams = new ParametersWithID(userAPubParams, userAId);
        byte[][] userBResults = userBKeyExchange.calculateKeyWithConfirmation(128, null, userAPubIdParams);
        System.out.println("用户B计算的密钥：" + Hex.toHexString(userBResults[0]));
        System.out.println();
        System.out.println("用户B将公钥发送给用户A：029754599adf0d8f71e8cc6bd7c284f0b1e4750c4cb1409d42fe0e4c5690cff705");
        System.out.println("用户B将随机公钥发送给用户A：021fdfb35f7fb1de5d65b54bd623f3caea0ff8da5e3bc716b6e4342080d8f540f4");
        System.out.println("用户B将自身USERID发送给用户A：31323334353637383837363534333231");
        System.out.println("用户B将SB发送给用户A：" + Hex.toHexString(userBResults[1]));
        System.out.println();

        // 用B的公钥、随机公钥、USERID生成参数
        // 我这里直接拿B的变量用了，实际要用传过来的公钥、随机公钥、USERID创建对应的userBPubK,、userBRandPubK、userBId
        SM2KeyExchangePublicParameters userBPubParams = new SM2KeyExchangePublicParameters(userBPubK, userBRandPubK);
        ParametersWithID userBPubIdParams = new ParametersWithID(userBPubParams, userBId);
        byte[][] userAResults = userAKeyExchange.calculateKeyWithConfirmation(128, userBResults[1], userBPubIdParams);

        System.out.println("步骤三：");
        System.out.println("用户A使用用户B的公钥、随机公钥、USERID来计算密钥及SA，并校验S1==SB");
        System.out.println("用户A计算的密钥：" + Hex.toHexString(userAResults[0]));
        System.out.println();
        System.out.println("用户A将SA发送给用户B：" + Hex.toHexString(userAResults[1]));
        System.out.println();

        System.out.println("步骤四：");
        // 用户B校验S2==SA
        Assert.assertArrayEquals(userBResults[2], userAResults[1]);
        System.out.println("用户B校验S2==SA");

        // 比较两者计算的密钥是否相等
        Assert.assertArrayEquals(userAResults[0], userBResults[0]);

        // 与预期密钥结果比较
        Assert.assertArrayEquals(userAResults[0], Hex.decodeStrict("d454c84c592dda5da97ce0d9b506ab7e"));
    }catch (Exception ex) {
        Assert.fail(ex.getMessage());
    }
}