CertificateExtensionsCommon.cs

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using System;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
 
namespace Internal.Cryptography.Pal;
 
internal static class CertificateExtensionsCommon
{
    public static T GetPublicKey<T>(this X509Certificate2 certificate, Predicate<X509Certificate2> matchesConstraints = null) where T : AsymmetricAlgorithm
    {
        if (certificate == null)
        {
            throw new ArgumentNullException("certificate");
        }
        string expectedOidValue = GetExpectedOidValue<T>();
        PublicKey publicKey = certificate.PublicKey;
        Oid oid = publicKey.Oid;
        if (expectedOidValue != oid.Value)
        {
            return null;
        }
        if (matchesConstraints != null && !matchesConstraints(certificate))
        {
            return null;
        }
        if (typeof(T) == typeof(RSA) || typeof(T) == typeof(DSA))
        {
            byte[] rawData = publicKey.EncodedKeyValue.RawData;
            byte[] rawData2 = publicKey.EncodedParameters.RawData;
            return (T)X509Pal.Instance.DecodePublicKey(oid, rawData, rawData2, certificate.Pal);
        }
        if (typeof(T) == typeof(ECDsa))
        {
            return (T)(AsymmetricAlgorithm)X509Pal.Instance.DecodeECDsaPublicKey(certificate.Pal);
        }
        if (typeof(T) == typeof(ECDiffieHellman))
        {
            return (T)(AsymmetricAlgorithm)X509Pal.Instance.DecodeECDiffieHellmanPublicKey(certificate.Pal);
        }
        throw new NotSupportedException(System.SR.NotSupported_KeyAlgorithm);
    }
 
    public static T GetPrivateKey<T>(this X509Certificate2 certificate, Predicate<X509Certificate2> matchesConstraints = null) where T : AsymmetricAlgorithm
    {
        if (certificate == null)
        {
            throw new ArgumentNullException("certificate");
        }
        string expectedOidValue = GetExpectedOidValue<T>();
        if (!certificate.HasPrivateKey || expectedOidValue != certificate.PublicKey.Oid.Value)
        {
            return null;
        }
        if (matchesConstraints != null && !matchesConstraints(certificate))
        {
            return null;
        }
        if (typeof(T) == typeof(RSA))
        {
            return (T)(AsymmetricAlgorithm)certificate.Pal.GetRSAPrivateKey();
        }
        if (typeof(T) == typeof(ECDsa))
        {
            return (T)(AsymmetricAlgorithm)certificate.Pal.GetECDsaPrivateKey();
        }
        if (typeof(T) == typeof(DSA))
        {
            return (T)(AsymmetricAlgorithm)certificate.Pal.GetDSAPrivateKey();
        }
        if (typeof(T) == typeof(ECDiffieHellman))
        {
            return (T)(AsymmetricAlgorithm)certificate.Pal.GetECDiffieHellmanPrivateKey();
        }
        throw new NotSupportedException(System.SR.NotSupported_KeyAlgorithm);
    }
 
    private static string GetExpectedOidValue<T>() where T : AsymmetricAlgorithm
    {
        if (typeof(T) == typeof(RSA))
        {
            return "1.2.840.113549.1.1.1";
        }
        if (typeof(T) == typeof(ECDsa) || typeof(T) == typeof(ECDiffieHellman))
        {
            return "1.2.840.10045.2.1";
        }
        if (typeof(T) == typeof(DSA))
        {
            return "1.2.840.10040.4.1";
        }
        throw new NotSupportedException(System.SR.NotSupported_KeyAlgorithm);
    }
}