const byte PrefixByteUknown = 23 << 3; // Base32-encodes to 'X...'
/// <summary>
/// Decodes a base 32 encoded NKey into a nkey seed and verifies the checksum.
/// </summary>
/// <param name="src">Base 32 encoded Nkey.</param>
/// <returns></returns>
public static byte[] Decode(string src)
{
byte[] raw = Base32.Decode(src);
ushort crc = (ushort)(raw[raw.Length - 2] | raw[raw.Length - 1] << 8);
// trim off the CRC16
int len = raw.Length - 2;
byte[] data = new byte[len];
Buffer.BlockCopy(raw, 0, data, 0, len);
if (crc != Crc16.Checksum(data))
{
throw new NATSException("Invalid CRC");
}
return(data);
}
internal static string Encode(byte prefixbyte, bool seed, byte[] src)
{
if (!IsValidPublicPrefixByte(prefixbyte))
{
throw new NATSException("Invalid prefix");
}
if (src.Length != 32)
{
throw new NATSException("Invalid seed size");
}
MemoryStream stream = new MemoryStream();
if (seed)
{
// In order to make this human printable for both bytes, we need to do a little
// bit manipulation to setup for base32 encoding which takes 5 bits at a time.
byte b1 = (byte)(PrefixByteSeed | (prefixbyte >> 5));
byte b2 = (byte)((prefixbyte & 31) << 3); // 31 = 00011111
stream.WriteByte(b1);
stream.WriteByte(b2);
}
else
{
stream.WriteByte(prefixbyte);
}
// write payload
stream.Write(src, 0, src.Length);
// Calculate and write crc16 checksum
byte[] checksum = BitConverter.GetBytes(Crc16.Checksum(stream.ToArray()));
stream.Write(checksum, 0, checksum.Length);
return(Base32.Encode(stream.ToArray()));
}