我正在开发一个应用程序,需要在secp256r1(NIST P-256,P-256,prime256v1)公钥的帮助下验证SHA256withECDSAsignatures.
公钥在某个较早的时间点由不同的应用程序生成,并以十六进制编码存储在我的数据库中.这里十六进制字符串的格式相当于OpenSSL在以前由openssl ecparam -genkey -name secp256r1 -out生成的文件x.pem上调用openssl ec -in x.pem -noout -text时生成的十六进制字符串x.pem.
消息和签名是从不同的应用程序接收的.
请考虑以下测试数据：
// Stored in Database
byte[] pubKey = DatatypeConverter.parseHexBinary("049a55ad1e210cd113457ccd3465b930c9e7ade5e760ef64b63142dad43a308ed08e2d85632e8ff0322d3c7fda14409eafdc4c5b8ee0882fe885c92e3789c36a7a");
// Received from Other Application
byte[] message = DatatypeConverter.parseHexBinary("54686973206973206a75737420736f6d6520706f696e746c6573732064756d6d7920737472696e672e205468616e6b7320616e7977617920666f722074616b696e67207468652074696d6520746f206465636f6465206974203b2d29");
byte[] signature = DatatypeConverter.parseHexBinary("304402205fef461a4714a18a5ca6dce6d5ab8604f09f3899313a28ab430eb9860f8be9d602203c8d36446be85383af3f2e8630f40c4172543322b5e8973e03fff2309755e654");
现在这应该是一个有效的签名.
我的目标是使用Java和/或Bouncycastle加密API验证消息上的签名.我创建了一个方法isValidSignaturefor：
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(getPublicKeyFromHex(pubKey));
ecdsaVerify.update(message);
return ecdsaVerify.verify(signature);
}
我试图提取公钥：
KeyFactory.generatePublic：
private static PublicKey getPublicKeyFromHex(byte[] pubKey) throws NoSuchAlgorithmException,InvalidKeySpecException {
KeyFactory fact = KeyFactory.getInstance("ECDSA",new BouncyCastleProvider());
return fact.generatePublic(new X509EncodedKeySpec(pubKey));
}
但这会抛出java.security.spec.InvalidKeySpecException(DER长度超过4个字节：26).
我该怎么做才能解析这个？
解决方法
Bouncy Castle example code on elliptic curve key pair Generation and key factories让我非常接近.
一旦我设法创建了一个ECDSA密钥工厂和secp256r1 / NIST P-256 / P-256 / prime256v1曲线的曲线规范,我就能够使用ECPointUtil.decodePoint来获得一个曲线点.然后,我可以生成一个公钥规范,使我能够生成如下公钥：
private 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;
}
