ECPrivateKey.cs

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using System.Formats.Asn1;
 
namespace System.Security.Cryptography.Asn1;
 
internal struct ECPrivateKey
{
    internal int Version;
 
    internal ReadOnlyMemory<byte> PrivateKey;
 
    internal System.Security.Cryptography.Asn1.ECDomainParameters? Parameters;
 
    internal ReadOnlyMemory<byte>? PublicKey;
 
    internal static System.Security.Cryptography.Asn1.ECPrivateKey Decode(ReadOnlyMemory<byte> encoded, AsnEncodingRules ruleSet)
    {
        return Decode(Asn1Tag.Sequence, encoded, ruleSet);
    }
 
    internal static System.Security.Cryptography.Asn1.ECPrivateKey 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 System.Security.Cryptography.Asn1.ECPrivateKey decoded)
    {
        decoded = default(System.Security.Cryptography.Asn1.ECPrivateKey);
        System.Formats.Asn1.AsnValueReader asnValueReader = reader.ReadSequence(expectedTag);
        ReadOnlySpan<byte> span = rebind.Span;
        if (!asnValueReader.TryReadInt32(out decoded.Version))
        {
            asnValueReader.ThrowIfNotEmpty();
        }
        int elementOffset;
        if (asnValueReader.TryReadPrimitiveOctetString(out var value))
        {
            decoded.PrivateKey = (span.Overlaps(value, out elementOffset) ? rebind.Slice(elementOffset, value.Length) : ((ReadOnlyMemory<byte>)value.ToArray()));
        }
        else
        {
            decoded.PrivateKey = asnValueReader.ReadOctetString();
        }
        System.Formats.Asn1.AsnValueReader reader2;
        if (asnValueReader.HasData && asnValueReader.PeekTag().HasSameClassAndValue(new Asn1Tag(TagClass.ContextSpecific, 0)))
        {
            reader2 = asnValueReader.ReadSequence(new Asn1Tag(TagClass.ContextSpecific, 0));
            System.Security.Cryptography.Asn1.ECDomainParameters.Decode(ref reader2, rebind, out var decoded2);
            decoded.Parameters = decoded2;
            reader2.ThrowIfNotEmpty();
        }
        if (asnValueReader.HasData && asnValueReader.PeekTag().HasSameClassAndValue(new Asn1Tag(TagClass.ContextSpecific, 1)))
        {
            reader2 = asnValueReader.ReadSequence(new Asn1Tag(TagClass.ContextSpecific, 1));
            if (reader2.TryReadPrimitiveBitString(out var unusedBitCount, out value))
            {
                decoded.PublicKey = (span.Overlaps(value, out elementOffset) ? rebind.Slice(elementOffset, value.Length) : ((ReadOnlyMemory<byte>)value.ToArray()));
            }
            else
            {
                decoded.PublicKey = reader2.ReadBitString(out unusedBitCount);
            }
            reader2.ThrowIfNotEmpty();
        }
        asnValueReader.ThrowIfNotEmpty();
    }
}