使用BouncyCastle验证Java中的ECDSA签名时出错

2023-01-04 10:29:01

我已经测试了一个解决方案,以验证与给定数据完美配合的ECDSA签名(How can I get a PublicKey object from EC public key bytes?).

这是数据：

byte[] pubKey = DatatypeConverter.parseHexBinary("049a55ad1e210cd113457ccd3465b930c9e7ade5e760ef64b63142dad43a308ed08e2d85632e8ff0322d3c7fda14409eafdc4c5b8ee0882fe885c92e3789c36a7a");
byte[] message = DatatypeConverter.parseHexBinary("54686973206973206a75737420736f6d6520706f696e746c6573732064756d6d7920737472696e672e205468616e6b7320616e7977617920666f722074616b696e67207468652074696d6520746f206465636f6465206974203b2d29");
byte[] signature = DatatypeConverter.parseHexBinary("304402205fef461a4714a18a5ca6dce6d5ab8604f09f3899313a28ab430eb9860f8be9d602203c8d36446be85383af3f2e8630f40c4172543322b5e8973e03fff2309755e654");

这是代码(打印为true)：

private static boolean isValidSignature(byte[] pubKey, byte[] message,byte[] signature) throws NoSuchAlgorithmException, NoSuchProviderException, InvalidKeyException, SignatureException, InvalidKeySpecException {
    Signature ecdsaVerify = Signature.getInstance("SHA256withECDSA", new BouncyCastleProvider());
    ecdsaVerify.initVerify(getPublicKeyFromBytes(pubKey));
    ecdsaVerify.update(message);
    return ecdsaVerify.verify(signature);
}

private static PublicKey getPublicKeyFromBytes(byte[] pubKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
    ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec("prime256v1");
    KeyFactory kf = KeyFactory.getInstance("ECDSA", new BouncyCastleProvider());
    ECNamedCurveSpec params = new ECNamedCurveSpec("prime256v1", spec.getCurve(), spec.getG(), spec.getN());
    ECPoint point =  ECPointUtil.decodePoint(params.getCurve(), pubKey);
    ECPublicKeySpec pubKeySpec = new ECPublicKeySpec(point, params);
    ECPublicKey pk = (ECPublicKey) kf.generatePublic(pubKeySpec);
    return pk;
}

public static void main (String[] args) {
    System.out.println(isValidSignature(pubKey, message, signature));
}

当我将签名和数据更改为已经实现的系统的示例输入时,我的问题出现了：

final static byte[] pubKey = DatatypeConverter.parseHexBinary("0447303876C6FED5550DF3EE1136989FCD87293D54A5D8E2F2F6D7FBE9A81089B889A5917443AF33E696178CEF4C9D6A4288B2745B29AF6C8BCAD1348F78EB9F9B");
final static byte[] message = DatatypeConverter.parseHexBinary("02158001f53611a06e2d1a270000013ed9305dc2780524015110500000002d0100140092569202017aa00c5dd30000000000000000000000000000000007d1000001020001b20788b80059f48d95cdefc8c6000200200030d41e0000012016840310a50733a9870fffd0430100");
final static byte[] signature = DatatypeConverter.parseHexBinary("531F8918FF250132959B01F7F56FDFD9E6CA3EC2144E12A6DA37C281489A3D96");

新数据输出此错误：

java.security.SignatureException: error decoding signature bytes.
    at org.bouncycastle.jcajce.provider.asymmetric.util.DSABase.engineVerify(Unknown Source)
    at java.security.Signature$Delegate.engineVerify(Signature.java:1178)
    at java.security.Signature.verify(Signature.java:612)
    at its.sec.exec.TestProgram.isValidSignature(TestProgram.java:168)
    at its.sec.exec.TestProgram.execution(TestProgram.java:101)
    at its.sec.exec.TestProgram.main(TestProgram.java:55)

我假设问题是关于安全消息附带的签名,因为：

>密钥对的长度和格式与示例相同.并且是正确的,因为它来自签署消息的证书.
>消息本身(有效负载)不应影响安全过程.

最后值得一提的是,我的文档说签名前面必须有一个名为“R”的字段,“包含椭圆曲线点的x坐标,这是由生成器元素乘以短暂的私钥产生的”,其长度必须是与签名相同(32字节).

有人能指出我在这里缺少的东西吗？

编辑：解决方案

正如Peter Dettman在他的回答中指出的那样,签名没有正确格式化(也是内容也不正确),以便通过verify()方法计算. Here是一个很好的解释,主要是说：

When encoded in DER, this (signature) becomes the following sequence of bytes:

0x30 b1 0x02 b2 (vr) 0x02 b3 (vs)

where:

b1 is a single byte value, equal to the length, in bytes, of the remaining list of bytes (from the first 0x02 to the end of the encoding);

b2 is a single byte value, equal to the length, in bytes, of (vr);

b3 is a single byte value, equal to the length, in bytes, of (vs);

(vr) is the signed big-endian encoding of the value “r”, of minimal length;

(vs) is the signed big-endian encoding of the value “s”, of minimal length.

应用该更改,签名增长到70个字节,执行输出没有错误.

解决方法:

BC(和其他提供者)实现所使用的预期ECDSA签名格式是DER编码的ASN.1序列,其包含两个整数值r和s.此签名格式已在ANSI X9.62中指定.这是您提供的第一组数据中的格式(请注意,签名总共为70个字节).

在第二组数据中,签名只有32个字节,根本不是ASN.1序列.我猜这个值只是s值,它缺少r值和它们的ASN.1 INTEGER编码,而是将值编码为与键大小相同的无符号大整数值.

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