public static bool VerifyMemeData(byte[] input, out byte[] output, MemeKeyIndex keyIndex) { output = null; if (input.Length < 0x60) { return(false); } var memekey = new MemeKey(keyIndex); output = (byte[])input.Clone(); var sigBuffer = new byte[0x60]; Array.Copy(input, input.Length - 0x60, sigBuffer, 0, 0x60); sigBuffer = memekey.RsaPublic(sigBuffer); using (var sha1 = SHA1.Create()) foreach (var orVal in new byte[] { 0, 0x80 }) { sigBuffer[0x0] |= orVal; sigBuffer.CopyTo(output, output.Length - 0x60); memekey.AesDecrypt(output).CopyTo(output, 0); // Check for 8-byte equality. if (BitConverter.ToUInt64(sha1.ComputeHash(output, 0, output.Length - 0x8), 0) == BitConverter.ToUInt64(output, output.Length - 0x8)) { return(true); } } output = null; return(false); }
private static bool DecryptCompare(byte[] output, byte[] sigBuffer, MemeKey key, SHA1 sha1) { sigBuffer.CopyTo(output, output.Length - 0x60); key.AesDecrypt(output).CopyTo(output, 0); // Check for 8-byte equality. var hash = sha1.ComputeHash(output, 0, output.Length - 0x8); var computed = BitConverter.ToUInt64(hash, 0); var existing = BitConverter.ToUInt64(output, output.Length - 0x8); return(computed == existing); }