使用 .Net 进行 RSA 签名并使用 OpenSSL 命令进行验证

Question

I'm trying to sign a simple data with C# using Sha1 hash and RSA and then verify it with the OpenSSL command.

For my tests, I've taken the localhost certificate that is preexisting on Windows.

Here's the code used with C#:

static void Main(string[] args)
{
    string sValTest = "sampledata";
    byte[] signature = Sign(sValTest, "localhost");
    string b64 = Convert.ToBase64String(signature);
    bool verified = Verify(sValTest, signature, @"pathToCer");
}

static byte[] Sign(string text, string certSubject)
{
    X509Store my = new X509Store(StoreName.My, StoreLocation.LocalMachine);
    my.Open(OpenFlags.ReadOnly);

    RSACryptoServiceProvider csp = null;
    foreach (X509Certificate2 cert in my.Certificates)
    {
        if (cert.Subject.Contains(certSubject))
        {
            csp = (RSACryptoServiceProvider)cert.PrivateKey;
            break;
        }
    }

    SHA1Managed sha1 = new SHA1Managed();
    byte[] data = Enconding.ASCII.GetBytes(text);
    byte[] hash = sha1.ComputeHash(data);

    return csp.SignHash(hash, CryptoConfig.MapNameToOID("SHA1"));
}

static bool Verify(string text, byte[] signature, string certPath)
{
    X509Certificate2 cert = new X509Certificate2(certPath);
    RSACryptoServiceProvider csp = RSACryptoServiceProvider)cert.PublicKey.Key;

    SHA1Managed sha1 = new SHA1Managed();
    byte[] data = Encoding.ASCII.GetBytes(text);
    byte[] hash = sha1.ComputeHash(data);

    return csp.VerifyHash(hash, CryptoConfig.MapNameToOID("SHA1"), signature);
}

(In that example, verified yields true )

I sent the public part of the PFX to my linux computer as well as the signature as base 64.

I then did the following:

base64 --decode sig.b64 > sig
openssl x509 -inform der -in localhost.cer  -out localhost.pem
openssl x509 -pubkey -noout -in localhost.pem > localhost.pub.pem
echo -n "sampledata" | openssl dgst -verify localhost.pub.pem -signature sig

Which ends with a Verification Failure .

I checked the serial number of the certificates on both sides and it matches. Just in case, I also checked the md5 of the signature in both stations, all clear.

Any pointers on where is the obvious fail?

Answer 1

You are missing the hash algorithm identifier into the openssl dgst command, which defaults to MD5.

Your correct last line is

echo -n "sampledata" | openssl dgst -verify localhost.pub.pem -signature sig -sha1