CertificateAsn.cs

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using System.Formats.Asn1;
using System.Security.Cryptography.Asn1;
 
namespace System.Security.Cryptography.X509Certificates.Asn1;
 
internal struct CertificateAsn
{
    internal TbsCertificateAsn TbsCertificate;
 
    internal System.Security.Cryptography.Asn1.AlgorithmIdentifierAsn SignatureAlgorithm;
 
    internal ReadOnlyMemory<byte> SignatureValue;
 
    internal void Encode(AsnWriter writer)
    {
        Encode(writer, Asn1Tag.Sequence);
    }
 
    internal void Encode(AsnWriter writer, Asn1Tag tag)
    {
        writer.PushSequence(tag);
        TbsCertificate.Encode(writer);
        SignatureAlgorithm.Encode(writer);
        writer.WriteBitString(SignatureValue.Span);
        writer.PopSequence(tag);
    }
 
    internal static CertificateAsn Decode(ReadOnlyMemory<byte> encoded, AsnEncodingRules ruleSet)
    {
        return Decode(Asn1Tag.Sequence, encoded, ruleSet);
    }
 
    internal static CertificateAsn Decode(Asn1Tag expectedTag, ReadOnlyMemory<byte> encoded, AsnEncodingRules ruleSet)
    {
        try
        {
            System.Formats.Asn1.AsnValueReader reader = new System.Formats.Asn1.AsnValueReader(encoded.Span, ruleSet);
            DecodeCore(ref reader, expectedTag, encoded, out var decoded);
            reader.ThrowIfNotEmpty();
            return decoded;
        }
        catch (AsnContentException inner)
        {
            throw new CryptographicException(System.SR.Cryptography_Der_Invalid_Encoding, inner);
        }
    }
 
    private static void DecodeCore(ref System.Formats.Asn1.AsnValueReader reader, Asn1Tag expectedTag, ReadOnlyMemory<byte> rebind, out CertificateAsn decoded)
    {
        decoded = default(CertificateAsn);
        System.Formats.Asn1.AsnValueReader reader2 = reader.ReadSequence(expectedTag);
        ReadOnlySpan<byte> span = rebind.Span;
        TbsCertificateAsn.Decode(ref reader2, rebind, out decoded.TbsCertificate);
        System.Security.Cryptography.Asn1.AlgorithmIdentifierAsn.Decode(ref reader2, rebind, out decoded.SignatureAlgorithm);
        if (reader2.TryReadPrimitiveBitString(out var unusedBitCount, out var value))
        {
            decoded.SignatureValue = (span.Overlaps(value, out var elementOffset) ? rebind.Slice(elementOffset, value.Length) : ((ReadOnlyMemory<byte>)value.ToArray()));
        }
        else
        {
            decoded.SignatureValue = reader2.ReadBitString(out unusedBitCount);
        }
        reader2.ThrowIfNotEmpty();
    }
}