c# - 不带参数的 RSASSA-PSS 使用 SHA-256 .Net 4.5 支持

Question

我正在尝试使用 System.Security.Cryptography(目标框架 .NET 4.5)创建 xml 数字签名，到目前为止，我设法使用以下方案创建和验证签名:RSA PKCS#1 v1.5 和 SHA-256:http://www.w3.org/2001/04/xmldsig-more#rsa-sha256

但是，我无法使用以下方案: “使用 SHA-256 的不带参数的 RSASSA-PSS”[RFC6931]:http://www.w3.org/2007/05/xmldsig-more#sha256-rsa-MGF1

显示的错误很明确“无法为提供的签名算法创建 SignatureDescription。”

对于“RSA PKCS#1 v1.5 和 SHA-256”，我添加了以下公共(public)类作为其签名:

   public class RSAPKCS1SHA256SignatureDescription : SignatureDescription
   {
        public RSAPKCS1SHA256SignatureDescription()
        {
            base.KeyAlgorithm = "System.Security.Cryptography.RSACryptoServiceProvider";
            base.DigestAlgorithm = "System.Security.Cryptography.SHA256Managed";
            base.FormatterAlgorithm = "System.Security.Cryptography.RSAPKCS1SignatureFormatter";
            base.DeformatterAlgorithm = "System.Security.Cryptography.RSAPKCS1SignatureDeformatter";
        }

        public override AsymmetricSignatureDeformatter CreateDeformatter(AsymmetricAlgorithm key)
        {
            AsymmetricSignatureDeformatter asymmetricSignatureDeformatter = (AsymmetricSignatureDeformatter)
            CryptoConfig.CreateFromName(base.DeformatterAlgorithm);
            asymmetricSignatureDeformatter.SetKey(key);
            asymmetricSignatureDeformatter.SetHashAlgorithm("SHA256");
            return asymmetricSignatureDeformatter;
        }
    }

但是，我不知道 .Net 4.5 是否支持“不带参数的 RSASSA-PSS 使用 SHA-256”，如果支持，如何设置其签名定义。

如果哪位有类似经验的可以提供帮助，我将不胜感激。

Answer 1

我终于明白了。诀窍是注册 XML 签名指定的算法，在我的例子中是“http://www.w3.org/2007/05/xmldsig-more#sha256-rsa-MGF1”。将其注册到自定义类，该类使用自定义签名格式化程序和去格式化程序，应用 RSASignaturePadding.Pss。

这是一个实现，您只需调用 RsaSsaPss.RegisterSha256RsaMgf1() 一次，例如从客户端的静态构造函数调用。然后，SignedXml.CheckSignature() 和 SignedXml.ComputeSignature() 自动处理指定此算法的任何 XML 签名。

在 Core 2.1 和 Framework 4.7.1 上测试:

/// <summary>
/// Contains classes for using RSA-SSA-PSS, as well as methods for registering them.
/// Registering such types adds support for them to SignedXml.
/// </summary>
public class RsaSsaPss
{
    /// <summary>
    /// Registers an implementation for "http://www.w3.org/2007/05/xmldsig-more#sha256-rsa-MGF1".
    /// </summary>
    public static void RegisterSha256RsaMgf1()
    {
        CryptoConfig.AddAlgorithm(typeof(RsaPssSha256SignatureDescription), "http://www.w3.org/2007/05/xmldsig-more#sha256-rsa-MGF1");
    }

    // Can add further registrations here...

    public class RsaPssSha256SignatureDescription : SignatureDescription
    {
        public RsaPssSha256SignatureDescription()
        {
            using (var rsa = RSA.Create())
            {
                this.KeyAlgorithm = rsa.GetType().AssemblyQualifiedName; // Does not like a simple algorithm name, but wants a type name (AssembyQualifiedName in Core)
            }
            this.DigestAlgorithm = "SHA256"; // Somehow wants a simple algorithm name
            this.FormatterAlgorithm = typeof(RsaPssSignatureFormatter).FullName;
            this.DeformatterAlgorithm = typeof(RsaPssSignatureDeformatter).FullName;
        }

        public override AsymmetricSignatureFormatter CreateFormatter(AsymmetricAlgorithm key)
        {
            var signatureFormatter = new RsaPssSignatureFormatter();
            signatureFormatter.SetKey(key);
            signatureFormatter.SetHashAlgorithm(this.DigestAlgorithm);
            return signatureFormatter;
        }

        public override AsymmetricSignatureDeformatter CreateDeformatter(AsymmetricAlgorithm key)
        {
            var signatureDeformatter = new RsaPssSignatureDeformatter();
            signatureDeformatter.SetKey(key);
            signatureDeformatter.SetHashAlgorithm(this.DigestAlgorithm);
            return signatureDeformatter;
        }

        public class RsaPssSignatureFormatter : AsymmetricSignatureFormatter
        {
            private RSA Key { get; set; }
            private string HashAlgorithmName { get; set; }

            public override void SetKey(AsymmetricAlgorithm key)
            {
                this.Key = (RSA)key;
            }

            public override void SetHashAlgorithm(string strName)
            {
                // Verify the name
                Oid.FromFriendlyName(strName, OidGroup.HashAlgorithm);

                this.HashAlgorithmName = strName;
            }

            public override byte[] CreateSignature(byte[] rgbHash)
            {
                return this.Key.SignHash(rgbHash, new HashAlgorithmName(this.HashAlgorithmName), RSASignaturePadding.Pss);
            }
        }

        public class RsaPssSignatureDeformatter : AsymmetricSignatureDeformatter
        {
            private RSA Key { get; set; }
            private string HashAlgorithmName { get; set; }

            public override void SetKey(AsymmetricAlgorithm key)
            {
                this.Key = (RSA)key;
            }

            public override void SetHashAlgorithm(string strName)
            {
                // Verify the name
                Oid.FromFriendlyName(strName, OidGroup.HashAlgorithm);

                this.HashAlgorithmName = strName;
            }

            public override bool VerifySignature(byte[] rgbHash, byte[] rgbSignature)
            {
                return this.Key.VerifyHash(rgbHash, rgbSignature, new HashAlgorithmName(this.HashAlgorithmName), RSASignaturePadding.Pss);
            }
        }
    }
}