带有 SHAwithECDSA 的 Java Signature.sign() 在多次运行时产生不同的结果

Question

我正在尝试使用 SHAwithECDSA 对一个不会改变的字节流进行签名，私钥也不会改变。无论您运行代码的频率如何，这都应该产生相同的结果。然而，我遇到了一些我无法解释的随机性，因为每次运行时结果输出都会发生变化。

这是我所做的(最小示例):

public byte[] sign() {
    Signature ecdsa = Signature.getInstance("SHA256withECDSA", "SunEC");

    // This is a hexadecimal byte sequence I need to sign
    String dataToBeSigned = "808112B43A3A381D1797BBBBBB973B99" + 
                         "9737B93397AA2917B1B0B737B734B1B0" + 
                         "B616B2BC3497A1AB43A3A381D1797BBB" +
                         "BBB973B999737B933979918181897981" +
                         "A17BC36B63239B4B396B6B7B93291B2B" +
                         "1B239B096B9B430991A9B22062349443" +
                         "1025687474703A2F2F7777772E77332E" +
                         "6F72672F54522F63616E6F6E6963616C" +
                         "2D6578692F4852D0E8E8E0745E5EEEEE" +
                         "EE5CEE665CDEE4CE5E646060625E6068" +
                         "5EF0DAD8CADCC646E6D0C2646A6C841A" +
                         "36BC07A00CB7DCAD662F3088A60A3D6A" +
                         "99431F81C122C2E9F1678EF531E95523" +
                         "70";

    String hexPrivKey = "B9134963F51C4414738435057F97BBF1" +
                        "010CABCB8DBDE9C5D48138396AA94B9D";
    byte[] privKey = DatatypeConverter.parseHexBinary(hexPrivKey);

    ecdsa.initSign(getPrivateKey(privKey));
    ecdsa.update(dataToBeSigned);
    byte[] signature = ecdsa.sign();

    System.out.println("Signature: " + DatatypeConverter.printHexBinary(signature));
}

public ECPrivateKey getPrivateKey(byte[] privateKeyBytes) {
    try {
        AlgorithmParameters parameters = AlgorithmParameters.getInstance("EC");
        parameters.init(new ECGenParameterSpec("secp256r1"));

        ECParameterSpec ecParameterSpec = parameters.getParameterSpec(ECParameterSpec.class);
        ECPrivateKeySpec ecPrivateKeySpec = new ECPrivateKeySpec(new BigInteger(privateKeyBytes), ecParameterSpec);

        ECPrivateKey privateKey = (ECPrivateKey) KeyFactory.getInstance("EC").generatePrivate(ecPrivateKeySpec);

        return privateKey;
    } catch (NoSuchAlgorithmException | InvalidKeySpecException | InvalidParameterSpecException e) {
        System.out.println(e.getClass().getSimpleName() + " occurred when trying to get private key from raw bytes", e);
        return null;
    }
}

您是否有任何提示，为什么我每次运行此代码时都不会产生相同的签名输出？提出了类似的问题here ，但还没有找到真正的答案。

另一个与此相关的问题:我看到 Signature 类提供了另一个 initSign 方法:initSign(私钥私钥，SecureRandom 随机)为什么我要在创建签名时插入随机源/种子？如果随机种子未知，接收方应该如何验证该签名？

感谢您的宝贵意见!马克

Answer 1

specification of the algorithm解释一下:

One characteristic of DSA and ECDSA is that they need to produce, for each signature generation, a fresh random value (hereafter designated as k). For effective security, k must be chosen randomly and uniformly from a set of modular integers, using a cryptographically secure process. Even slight biases in that process may be turned into attacks on the signature schemes.

所以您所看到的是完全正常的。当然，算法的设计者让接收者可以验证签名，否则就没有意义了。这就是您的测试应该验证的内容。