X509SubjectKeyIdentifierExtension.cs

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using Internal.Cryptography;
using Internal.Cryptography.Pal;
 
namespace System.Security.Cryptography.X509Certificates;
 
public sealed class X509SubjectKeyIdentifierExtension : X509Extension
{
    private string _subjectKeyIdentifier;
 
    private bool _decoded;
 
    public string? SubjectKeyIdentifier
    {
        get
        {
            if (!_decoded)
            {
                X509Pal.Instance.DecodeX509SubjectKeyIdentifierExtension(base.RawData, out var subjectKeyIdentifier);
                _subjectKeyIdentifier = subjectKeyIdentifier.ToHexStringUpper();
                _decoded = true;
            }
            return _subjectKeyIdentifier;
        }
    }
 
    public X509SubjectKeyIdentifierExtension()
        : base(System.Security.Cryptography.Oids.SubjectKeyIdentifierOid)
    {
        _subjectKeyIdentifier = null;
        _decoded = true;
    }
 
    public X509SubjectKeyIdentifierExtension(AsnEncodedData encodedSubjectKeyIdentifier, bool critical)
        : base(System.Security.Cryptography.Oids.SubjectKeyIdentifierOid, encodedSubjectKeyIdentifier.RawData, critical)
    {
    }
 
    public X509SubjectKeyIdentifierExtension(byte[] subjectKeyIdentifier, bool critical)
        : this(subjectKeyIdentifier.AsSpanParameter("subjectKeyIdentifier"), critical)
    {
    }
 
    public X509SubjectKeyIdentifierExtension(ReadOnlySpan<byte> subjectKeyIdentifier, bool critical)
        : base(System.Security.Cryptography.Oids.SubjectKeyIdentifierOid, EncodeExtension(subjectKeyIdentifier), critical)
    {
    }
 
    public X509SubjectKeyIdentifierExtension(PublicKey key, bool critical)
        : this(key, X509SubjectKeyIdentifierHashAlgorithm.Sha1, critical)
    {
    }
 
    public X509SubjectKeyIdentifierExtension(PublicKey key, X509SubjectKeyIdentifierHashAlgorithm algorithm, bool critical)
        : base(System.Security.Cryptography.Oids.SubjectKeyIdentifierOid, EncodeExtension(key, algorithm), critical)
    {
    }
 
    public X509SubjectKeyIdentifierExtension(string subjectKeyIdentifier, bool critical)
        : base(System.Security.Cryptography.Oids.SubjectKeyIdentifierOid, EncodeExtension(subjectKeyIdentifier), critical)
    {
    }
 
    public override void CopyFrom(AsnEncodedData asnEncodedData)
    {
        base.CopyFrom(asnEncodedData);
        _decoded = false;
    }
 
    private static byte[] EncodeExtension(ReadOnlySpan<byte> subjectKeyIdentifier)
    {
        if (subjectKeyIdentifier.Length == 0)
        {
            throw new ArgumentException(System.SR.Arg_EmptyOrNullArray, "subjectKeyIdentifier");
        }
        return X509Pal.Instance.EncodeX509SubjectKeyIdentifierExtension(subjectKeyIdentifier);
    }
 
    private static byte[] EncodeExtension(string subjectKeyIdentifier)
    {
        if (subjectKeyIdentifier == null)
        {
            throw new ArgumentNullException("subjectKeyIdentifier");
        }
        byte[] array = subjectKeyIdentifier.DecodeHexString();
        return EncodeExtension(array);
    }
 
    private static byte[] EncodeExtension(PublicKey key, X509SubjectKeyIdentifierHashAlgorithm algorithm)
    {
        if (key == null)
        {
            throw new ArgumentNullException("key");
        }
        byte[] array = GenerateSubjectKeyIdentifierFromPublicKey(key, algorithm);
        return EncodeExtension(array);
    }
 
    private static byte[] GenerateSubjectKeyIdentifierFromPublicKey(PublicKey key, X509SubjectKeyIdentifierHashAlgorithm algorithm)
    {
        switch (algorithm)
        {
        case X509SubjectKeyIdentifierHashAlgorithm.Sha1:
            return SHA1.HashData(key.EncodedKeyValue.RawData);
        case X509SubjectKeyIdentifierHashAlgorithm.ShortSha1:
        {
            byte[] array = SHA1.HashData(key.EncodedKeyValue.RawData);
            byte[] array2 = new byte[8];
            Buffer.BlockCopy(array, array.Length - 8, array2, 0, array2.Length);
            array2[0] &= 15;
            array2[0] |= 64;
            return array2;
        }
        case X509SubjectKeyIdentifierHashAlgorithm.CapiSha1:
            return X509Pal.Instance.ComputeCapiSha1OfPublicKey(key);
        default:
            throw new ArgumentException(System.SR.Format(System.SR.Arg_EnumIllegalVal, algorithm), "algorithm");
        }
    }
}