使用带有 SHA256 证书的 ECDSA 进行 C# 签名验证

Question

我正在尝试使用 C# 和内置的 Crypto 库来验证使用 EC 密钥 + SHA256 创建的签名。这就是我正在做的事情。

我已经使用 openssl 创建了一个私钥和相应的证书：

$ openssl ecparam -genkey -name prime256v1 -out ca.key
$ openssl req -x509 -new -SHA256 -nodes -key ca.key -days 36500 -out ca.crt

这是我正在使用的键（别担心，它们并不重要）：

$ cat ca.key 
-----BEGIN EC PARAMETERS-----
BggqhkjOPQMBBw==
-----END EC PARAMETERS-----
-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIHd3OvRV1nEnoDxGzzemX1x8l2rHasWH3L/LflUGg5vloAoGCCqGSM49
AwEHoUQDQgAE7f1xwQL5m/UcN4zL+zsly6V1g3/wNcL5TdCfWt0XfnUfg0x+RsIf
1uerBnhrmhH0cN9o0xfXg5B3hURFlXVuEQ==
-----END EC PRIVATE KEY-----

$ cat ca.crt 
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

然后我有一个包含字符串“Hello”的简单数据文件。然后我使用 openssl 签署该文件，如下所示：

$ openssl dgst -sha256 -sign ca.key data.txt > sig
$ base64 sig 
MEUCIQD5593C/NBhHA1DILT72gjhGj/lKjom9vYP+JbuypBrxQIgNAjYT1LihEpPbUhe1n9ccUHQ
vw676bGqOTEU/25qcRQ=

然后我可以通过首先从证书中提取公钥然后使用它来验证来验证签名：

$ openssl x509 -pubkey -noout -in ca.crt > ca.pub
$ cat ca.pub 
-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE7f1xwQL5m/UcN4zL+zsly6V1g3/w
NcL5TdCfWt0XfnUfg0x+RsIf1uerBnhrmhH0cN9o0xfXg5B3hURFlXVuEQ==
-----END PUBLIC KEY-----
$ openssl dgst -verify ca.pub -sha256 -signature sig data.txt 
Verified OK

然后我尝试使用 C# (.NET Core 3.1) 来验证签名。代码如下：

using System;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Text;

namespace security_sandbox
{
    class Program
    {
        static void Main(string[] args)
        {
            var certData = Encoding.ASCII.GetBytes(
                @"-----BEGIN CERTIFICATE-----
MIIB4TCCAYegAwIBAgIUKt0WdaKI2eRXBO2nVk+OF6AZqHMwCgYIKoZIzj0EAwIw
RTELMAkGA1UEBhMCQVUxEzARBgNVBAgMClNvbWUtU3RhdGUxITAfBgNVBAoMGElu
dGVybmV0IFdpZGdpdHMgUHR5IEx0ZDAgFw0yMDA1MDcxMzM2MTNaGA8yMTIwMDQx
MzEzMzYxM1owRTELMAkGA1UEBhMCQVUxEzARBgNVBAgMClNvbWUtU3RhdGUxITAf
BgNVBAoMGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDBZMBMGByqGSM49AgEGCCqG
SM49AwEHA0IABO39ccEC+Zv1HDeMy/s7JculdYN/8DXC+U3Qn1rdF351H4NMfkbC
H9bnqwZ4a5oR9HDfaNMX14OQd4VERZV1bhGjUzBRMB0GA1UdDgQWBBRGuUmsyB2h
JCXMRTVMRTcdoWZQaDAfBgNVHSMEGDAWgBRGuUmsyB2hJCXMRTVMRTcdoWZQaDAP
BgNVHRMBAf8EBTADAQH/MAoGCCqGSM49BAMCA0gAMEUCIGG8tQZlh7aJaI34Y7jq
44SmSc/ule9MgjIX+Gg+i5vwAiEA9Jb/304KO4t9OMqFMQeWZXIHdzhDFBwx7FWz
78+UsnY=
-----END CERTIFICATE-----");

            var cert = new X509Certificate2(certData);
            var ecdsa = cert.GetECDsaPublicKey();

            var data = Encoding.ASCII.GetBytes("Hello");
            var signature = Convert.FromBase64String("MEUCIQD5593C/NBhHA1DILT72gjhGj/lKjom9vYP+JbuypBrxQIgNAjYT1LihEpPbUhe1n9ccUHQvw676bGqOTEU/25qcRQ=");

            var success = ecdsa.VerifyData(data, signature, HashAlgorithmName.SHA256);

            if (success)
            {
                Console.WriteLine("Verified");
            } else
            {
                Console.WriteLine("Failed");
            }
        }
    }
}

不幸的是，它总是无法通过验证。哪里错了？

Answer 1

事实证明，.NET 中缺乏与 PEM/OpenSSL 兼容的操作工具非常令人沮丧。我最终使用Bouncy Castle 加载证书或公钥，然后使用它来验证我的 ASN 签名。这是一个完整的工作代码示例，演示了如何使用证书和 PEM 公钥以及使用 ASN 编码的签名来执行签名验证。

using System;
using System.IO;
using System.Text;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.OpenSsl;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.X509;

namespace security_sandbox
{
    class Program
    {
        static void Main(string[] args)
        {

            var certificateString =  @"-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----";
            var pemreader = new PemReader(new StringReader(certificateString));
            var cert = (X509Certificate)pemreader.ReadObject();

            // Alternatively, load the public key directly
            var pubkeyString = 
@"-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE7f1xwQL5m/UcN4zL+zsly6V1g3/w
NcL5TdCfWt0XfnUfg0x+RsIf1uerBnhrmhH0cN9o0xfXg5B3hURFlXVuEQ==
-----END PUBLIC KEY-----";
            pemreader = new PemReader(new StringReader(pubkeyString));
            var pubkey = (AsymmetricKeyParameter)pemreader.ReadObject();

            var data = "Hello";
            var signature = Convert.FromBase64String("MEUCIQD5593C/NBhHA1DILT72gjhGj/lKjom9vYP+JbuypBrxQIgNAjYT1LihEpPbUhe1n9ccUHQvw676bGqOTEU/25qcRQ=");

            // Verify using the public key
            var signer = SignerUtilities.GetSigner("SHA-256withECDSA");
            signer.Init(false, pubkey);
            signer.BlockUpdate(Encoding.ASCII.GetBytes(data), 0, data.Length);
            var success = signer.VerifySignature(signature);

            if (success) {
                Console.WriteLine("Signature verified successfully using public key");
            } else {
                Console.WriteLine("Failed to verify signature using public key");
            }

            // Verify using the certificate - the certificate's public key is extracted using the GetPublicKey method.
            signer.Init(false, cert.GetPublicKey());
            signer.BlockUpdate(Encoding.ASCII.GetBytes(data), 0, data.Length);
            success = signer.VerifySignature(signature);

            if (success) {
                Console.WriteLine("Signature verified successfully using certificate");
            } else {
                Console.WriteLine("Failed to verify signature using certificate");
            }
        }
    }
}