static int Main(string[] args)
{
if (args.Length < 1)
{
Console.WriteLine(PuzzleFileFns.StandardOneParamRequiredErrorMessage);
return(1);
}
var allLines = File.ReadAllLines(args[0]);
int payloadStartLine = PuzzleFileFns.GetLinePayloadStartsAt(allLines);
var payload = PuzzleFileFns.GetPayloadAsOneLongString(allLines, payloadStartLine);
Debug.Assert(payload.StartsWith("<~$O=cdK]PkWZ"));
Debug.Assert(payload.EndsWith("/UHOHO4@~>"));
Debug.Assert(payload.Contains("\n") == false);
var payloadSpan = Ascii85Fns.DecodeAsSpan(payload, 2);
var kekSpan = payloadSpan.Slice(0, 32);
var ivWrapSpan = payloadSpan.Slice(32, 8);
var encryptedKeySpan = payloadSpan.Slice(40, 40);
var ivSpan = payloadSpan.Slice(80, 16);
var encryptedPayloadSpan = payloadSpan.Slice(96);
Debug.Assert(HexFns.ToHex(kekSpan.ToArray()) == "0b07c91284e54bd5b3a356451eda9d38e9770f505fef14f0e62c74f3fd1f286a");
Debug.Assert(HexFns.ToHex(ivWrapSpan.ToArray()) == "badc0ffeebadc0de");
Debug.Assert(HexFns.ToHex(ivSpan.ToArray()) == "8c2e487274dbebe699677f1b54ebbeb4");
var plainTextKeyBytes = CryptoFns.DecryptKey(kekSpan.ToArray(),
ivWrapSpan.ToArray(), encryptedKeySpan.ToArray());
Debug.Assert(HexFns.ToHex(plainTextKeyBytes) == "c68cade3c9c973067b383b77713ddac8072e05d2bb54a8a2d45b312ce8817024");
var plainText = CryptoFns.Decrypt(plainTextKeyBytes, ivSpan.ToArray(),
encryptedPayloadSpan.ToArray());
Console.WriteLine(Encoding.ASCII.GetString(plainText));
return(0);
}
// Returns the contents of the current Block in a hex string.
public override string ToString()
{
// SoapHexBinary hex = new SoapHexBinary(Bytes);
// return hex.ToString();
return(HexFns.ToHex(Bytes));
}