private static byte[] DecodeBase64Check(string base64encoded)
{
// TODO logic copied from Base58.decodeChecked -> can this be reused
// here?
Base64Encoder enc = new Base64Encoder();
byte[] decoded = enc.DecodeData(base64encoded);
if (decoded.Length < 4)
{
throw new FormatException("Input too short");
}
byte[] data = new byte[decoded.Length - 4];
byte[] checksum = new byte[4];
Buffer.BlockCopy(decoded, 0, data, 0, data.Length);
Buffer.BlockCopy(decoded, data.Length, checksum, 0, 4);
SHA256Managed m = new SHA256Managed();
byte[] re = m.ComputeHash(data);
re = m.ComputeHash(re);
byte[] actualChecksum = new byte[4];
Buffer.BlockCopy(re, 0, actualChecksum, 0, 4);
if (!Enumerable.SequenceEqual(checksum, actualChecksum))
{
throw new FormatException("Checksum does not validate");
}
return(data);
}
private static string EncodeBase64Check(byte[] input)
{
SHA256Managed m = new SHA256Managed();
byte[] re = m.ComputeHash(input);
re = m.ComputeHash(re);
byte[] checksum = new byte[4];
Buffer.BlockCopy(re, 0, checksum, 0, 4);
byte[] base64checksum = input.Concatenate(checksum);
Base64Encoder enc = new Base64Encoder();
return(enc.EncodeData(base64checksum));
}
