RSAPublicKeyAsn.cs

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using System.Formats.Asn1;
using System.Numerics;
 
namespace System.Security.Cryptography.Asn1;
 
internal struct RSAPublicKeyAsn
{
    internal BigInteger Modulus;
 
    internal BigInteger PublicExponent;
 
    internal static RSAPublicKeyAsn Decode(ReadOnlyMemory<byte> encoded, AsnEncodingRules ruleSet)
    {
        return Decode(Asn1Tag.Sequence, encoded, ruleSet);
    }
 
    internal static RSAPublicKeyAsn Decode(Asn1Tag expectedTag, ReadOnlyMemory<byte> encoded, AsnEncodingRules ruleSet)
    {
        try
        {
            AsnValueReader reader = new 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 AsnValueReader reader, Asn1Tag expectedTag, ReadOnlyMemory<byte> rebind, out RSAPublicKeyAsn decoded)
    {
        decoded = default(RSAPublicKeyAsn);
        AsnValueReader asnValueReader = reader.ReadSequence(expectedTag);
        decoded.Modulus = asnValueReader.ReadInteger();
        decoded.PublicExponent = asnValueReader.ReadInteger();
        asnValueReader.ThrowIfNotEmpty();
    }
}