/// <summary>
/// Decodes attested credential data.
/// </summary>
public AttestedCredentialData(BinaryReader reader)
{
if (reader.BaseStream.Length < _minLength)
{
throw new Fido2VerificationException("Not enough bytes to be a valid AttestedCredentialData");
}
// First 16 bytes is AAGUID
var aaguidBytes = reader.ReadBytes(Marshal.SizeOf(typeof(Guid)));
if (BitConverter.IsLittleEndian)
{
// GUID from authenticator is big endian. If we are on a little endian system, convert.
AaGuid = FromBigEndian(aaguidBytes);
}
else
{
AaGuid = new Guid(aaguidBytes);
}
// Byte length of Credential ID, 16-bit unsigned big-endian integer.
var credentialIDLenBytes = reader.ReadBytes(sizeof(ushort));
if (BitConverter.IsLittleEndian)
{
// Credential ID length from authenticator is big endian. If we are on little endian system, convert.
Array.Reverse(credentialIDLenBytes);
}
// Convert the read bytes to uint16 so we know how many bytes to read for the credential ID
var credentialIDLen = BitConverter.ToUInt16(credentialIDLenBytes, 0);
// Read the credential ID bytes
CredentialID = reader.ReadBytes(credentialIDLen);
// "Determining attested credential data's length, which is variable, involves determining
// credentialPublicKey's beginning location given the preceding credentialId's length, and
// then determining the credentialPublicKey's length"
// Read the CBOR object from the stream
CredentialPublicKey = new CredentialPublicKey(reader.BaseStream);
}
/// <summary>
/// Instantiates an AttestedCredentialData object from an aaguid, credentialID, and CredentialPublicKey
/// </summary>
/// <param name="aaguid"></param>
/// <param name="credentialID"></param>
/// <param name="cpk"></param>
public AttestedCredentialData(Guid aaguid, byte[] credentialID, CredentialPublicKey cpk)
{
AaGuid = aaguid;
CredentialID = credentialID;
CredentialPublicKey = cpk;
}