internal static bool TryParse(ReadOnlySpan <byte> bytes, out PgpPacket packet)
{
if (bytes.Length == 0)
{
// Insufficient data
packet = null;
return(false);
}
if (!TryReadHeader(ref bytes, out var tag, out var length))
{
packet = null;
return(false);
}
// Slice the input
bytes = bytes.Slice(0, length);
switch (tag)
{
case PgpPacketTag.Signature:
return(TryParseSignature(ref bytes, out packet));
default:
throw new FormatException($"Unsupported packet type: ");
}
}
private static bool TryParseSignature(ref ReadOnlySpan <byte> bytes, out PgpPacket packet)
{
if (bytes.Length == 0)
{
packet = null;
return(false);
}
var version = (int)bytes[0];
bytes = bytes.Slice(1);
if (version == 3)
{
return(TryParseV3Signature(ref bytes, out packet));
}
else if (version == 4)
{
return(TryParseV4Signature(ref bytes, out packet));
}
else
{
throw new NotSupportedException($"Unsupported signature version: {version}");
}
}
private static bool TryParseV4Signature(ref ReadOnlySpan <byte> bytes, out PgpPacket packet)
{
if (bytes.Length < 5)
{
// Insufficient data for the initial headers
packet = null;
return(false);
}
var type = (SignatureType)bytes[0];
var pkAlgorithm = bytes[1];
var hashAlgorithm = bytes[2];
var hashedDataLength = BinaryPrimitives.ReadInt16BigEndian(bytes.Slice(3, 2));
var readSoFar = 5;
if (bytes.Length < readSoFar + hashedDataLength)
{
// Insufficient data for the hashed data
packet = null;
return(false);
}
var hashedData = bytes.Slice(readSoFar, hashedDataLength);
readSoFar += hashedDataLength;
if (bytes.Length < readSoFar + 2)
{
// Insufficient data for the unhashed data length
packet = null;
return(false);
}
var unhashedDataLength = BinaryPrimitives.ReadInt16BigEndian(bytes.Slice(readSoFar, 2));
readSoFar += 2;
if (bytes.Length < readSoFar + unhashedDataLength)
{
// Insufficient data for the unhashed data
packet = null;
return(false);
}
var unhashedData = bytes.Slice(readSoFar, unhashedDataLength);
readSoFar += unhashedDataLength;
packet = new SignaturePacket(4, type, pkAlgorithm, hashAlgorithm, hashedData.ToArray(), unhashedData.ToArray(), bytes.Length);
return(true);
}
private static bool TryParseV3Signature(ref ReadOnlySpan <byte> bytes, out PgpPacket packet)
{
throw new NotSupportedException("Version 3 signatures are not yet supported.");
}