public static byte[] ToUInt16BigEndianBytes(this TpmAlg alg)
{
var bytes = new byte[2];
BinaryPrimitives.WriteUInt16BigEndian(bytes, (ushort)alg);
return(bytes);
}
public static (UInt16 size, byte[] name) NameFromTPM2BName(Memory <byte> ab, ref int offset)
{
// TCG TPM Rev 2.0, part 2, structures, section 10.5.3, TPM2B_NAME
// This buffer holds a Name for any entity type.
// The type of Name in the structure is determined by context and the size parameter.
var totalBytes = AuthDataHelper.GetSizedByteArray(ab, ref offset, 2);
UInt16 totalSize = 0;
if (null != totalBytes)
{
totalSize = BitConverter.ToUInt16(totalBytes.ToArray().Reverse().ToArray(), 0);
}
UInt16 size = 0;
var bytes = AuthDataHelper.GetSizedByteArray(ab, ref offset, 2);
if (null != bytes)
{
size = BitConverter.ToUInt16(bytes.ToArray().Reverse().ToArray(), 0);
}
// If size is four, then the Name is a handle.
if (4 == size)
{
throw new Fido2VerificationException("Unexpected handle in TPM2B_NAME");
}
// If size is zero, then no Name is present.
if (0 == size)
{
throw new Fido2VerificationException("Unexpected no name found in TPM2B_NAME");
}
// Otherwise, the size shall be the size of a TPM_ALG_ID plus the size of the digest produced by the indicated hash algorithm.
TpmAlg tpmalg = TpmAlg.TPM_ALG_ERROR;
byte[] name = null;
if (Enum.IsDefined(typeof(TpmAlg), size))
{
tpmalg = (TpmAlg)size;
if (tpmAlgToDigestSizeMap.ContainsKey(tpmalg))
{
name = AuthDataHelper.GetSizedByteArray(ab, ref offset, tpmAlgToDigestSizeMap[tpmalg]);
}
}
if (totalSize != bytes.Length + name.Length)
{
throw new Fido2VerificationException("Unexpected no name found in TPM2B_NAME");
}
return(size, name);
}