我正在发送一个SIGNED使用 c# 和 asp.net 向 idp 发出 authnRequest。我的代码对 authnRequest 进行签名，但签名验证在 idp 处失败。

Details

我尝试了很多解决方案但没有成功。 这就是我正在遵循的准则所做的事情https://docs.oasis-open.org/security/saml/v2.0/saml-bindings-2.0-os.pdf https://docs.oasis-open.org/security/saml/v2.0/saml-bindings-2.0-os.pdf:

• STEPS

  1. 缩小身份验证请求，然后对其进行 Base64 编码，最后对其进行 Url 编码。我们称之为 AR
  2. 对 RelayState 进行 URL 编码。我们称之为RS
  3. Url 对签名算法字符串进行编码。我们就叫它SA吧
  4. 所以要签名的字符串现在变成了SAMLRequest=AR&RelayState=RS&SigAlg=SA
  5. 现在，我使用我们的私钥（服务提供商私钥）对我们在步骤 #4 中获得的字符串进行签名。 6.我得到的结果签名，我对其进行base 64编码，然后对其进行URL编码。因此我得到了一个base64和url编码的签名。我们就叫它SG吧
  6. 现在，我将在步骤#6 中获得的签名附加到步骤#4 中的查询字符串。所以最终的查询字符串变成SAMLRequest=AR&RelayState=RS&SigAlg=SA&Signature=SG

所有这些工作正常，但签名验证失败！

这是我的代码，与此处找到的代码类似https://github.com/Sustainsys/Saml2/blob/v0.21.2/Kentor.AuthServices/WebSSO/Saml2RedirectBinding.cs#L53-L68 https://github.com/Sustainsys/Saml2/blob/v0.21.2/Kentor.AuthServices/WebSSO/Saml2RedirectBinding.cs#L53-L68

protected void btnSendAuthRequest_Click(object sender, EventArgs e)
    {
        string authRequest = txtInput.Text;
        //authRequest = authRequest.TrimEnd('\r', '\n');
        authRequest = DeflateBase64UrlEncode(authRequest);

        string spPrivateKey= txtKey.Text;
        string relayState = HttpUtility.UrlEncode("https://example.com/pages/home.aspx");

        string qs = "SAMLRequest=" + authRequest + "&RelayState=" + relayState;
        qs = AddSignature(qs, spPrivateKey);

        txtOutput.Text = qs;
    }

public string AddSignature(string queryString, string PrivateKeyNoHeaders)
    {
        RSACryptoServiceProvider tmpRsa = RSAKeyTests.RSAKeyUtils.DecodePrivateKeyInfo(Convert.FromBase64String(PrivateKeyNoHeaders));

        string signingAlgorithmUrl = "http://www.w3.org/2000/09/xmldsig#rsa-sha1";

        queryString += "&SigAlg=" + HttpUtility.UrlEncode(signingAlgorithmUrl);

        var signatureDescription = (SignatureDescription)CryptoConfig.CreateFromName(signingAlgorithmUrl);
        HashAlgorithm hashAlg = signatureDescription.CreateDigest();
        hashAlg.ComputeHash(Encoding.UTF8.GetBytes(queryString));

AsymmetricSignatureFormatter asymmetricSignatureFormatter =
            signatureDescription.CreateFormatter(
                ((RSACryptoServiceProvider)tmpRsa));
        //.GetSha256EnabledRSACryptoServiceProvider()); 
        // Is the signature failing because of above ? 

        byte[] signatureValue = asymmetricSignatureFormatter.CreateSignature(hashAlg);
        queryString += "&Signature=" + HttpUtility.UrlEncode(Convert.ToBase64String(signatureValue));

        return queryString;
    }

private string DeflateBase64UrlEncode(string input)
    {
        var inputs = string.Format(input, Guid.NewGuid());
        var bytes = Encoding.UTF8.GetBytes(inputs);
        using (var output = new MemoryStream())
        {
            using (var zip = new DeflateStream(output, CompressionMode.Compress))
            {
                zip.Write(bytes, 0, bytes.Length);
            }
            var base64 = Convert.ToBase64String(output.ToArray());
            return HttpUtility.UrlEncode(base64);
        }
    }

CryptoConfig.createFromName(...) 不知道 https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.cryptoconfig?view=netframework-4.8 about http://www.w3.org/2000/09/xmldsig#rsa-sha1作为摘要+签名算法。如果CryptoConfig.createFromName()不返回 null，无论注册什么算法http://www.w3.org/2000/09/xmldsig#rsa-sha1可能不是 RSA-SHA1。这是一个显式的实现SignatureDescription使用 RSA 和 SHA1：

public class RSASHA1SignatureDescription : SignatureDescription {

        public RSASHA1SignatureDescription() {
            KeyAlgorithm = "System.Security.Cryptography.RSA";
            DigestAlgorithm = "System.Security.Cryptography.SHA1Cng";
            FormatterAlgorithm = "System.Security.Cryptography.RSAPKCS1SignatureFormatter";
            DeformatterAlgorithm = "System.Security.Cryptography.RSAPKCS1SignatureDeformatter";
            _hashAlgorithm = "SHA1";
        }

        public override AsymmetricSignatureDeformatter CreateDeformatter(AsymmetricAlgorithm key) {
            AsymmetricSignatureDeformatter item = (AsymmetricSignatureDeformatter) CryptoConfig.CreateFromName(DeformatterAlgorithm);
            item.setKey(key);
            item.SetHashAlgorithm(_hashAlgorithm);
            return item;
        }

        public override AsymmetricSignatureFormatter CreateFormatter(AsymmetricAlgorithm key) {
            AsymmetricSignatureFormatter item = (AsymmetricSignatureFormatter) CryptoConfig.CreateFromName(FormatterAlgorithm);
            item.setKey(key);
            item.SetHashAlgorithm(_hashAlgorithm);
            return item;
        }

        private string _hashAlgorithm;
    }

另一种可能性是，您验证签名时不需要 rsa-sha1（许多身份提供商通过配置禁止 rsa-sha1）或者验证不正确。尝试使用真正的 IdP（例如 Okta 或 Salesforce）注册并在那里进行验证。