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);
}
public static byte[] SignMemeData(byte[] input, MemeKeyIndex keyIndex = MemeKeyIndex.PokedexAndSaveFile)
{
// Validate Input
if (input.Length < 0x60)
{
throw new ArgumentException("Cannot memesign a buffer less than 0x60 bytes in size!");
}
var memekey = new MemeKey(keyIndex);
if (!memekey.CanResign)
{
throw new ArgumentException("Cannot sign with the specified memekey!");
}
var output = (byte[])input.Clone();
// Copy in the SHA1 signature
using (var sha1 = SHA1.Create())
{
Array.Copy(sha1.ComputeHash(input, 0, input.Length - 8), 0, output, output.Length - 8, 8);
}
// Perform AES operations
output = memekey.AesEncrypt(output);
var sigBuffer = new byte[0x60];
Array.Copy(output, output.Length - 0x60, sigBuffer, 0, 0x60);
sigBuffer[0] &= 0x7F;
sigBuffer = memekey.RsaPrivate(sigBuffer);
sigBuffer.CopyTo(output, output.Length - 0x60);
return(output);
}
public static bool VerifyMemeData(byte[] input, out byte[] output, MemeKeyIndex keyIndex)
{
if (input.Length < 0x60)
{
output = input;
return(false);
}
var key = new MemeKey(keyIndex);
output = (byte[])input.Clone();
var sigBuffer = key.RsaPublic(input.SliceEnd(input.Length - 0x60));
using var sha1 = SHA1.Create();
if (DecryptCompare(output, sigBuffer, key, sha1))
{
return(true);
}
sigBuffer[0x0] |= 0x80;
if (DecryptCompare(output, sigBuffer, key, sha1))
{
return(true);
}
output = input;
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);
}
public static bool VerifyMemePOKE(byte[] input, out byte[] output)
{
if (input.Length < 0x60)
{
throw new ArgumentException("Invalid POKE buffer!");
}
var memeLen = input.Length - 8;
var memeIndex = MemeKeyIndex.PokedexAndSaveFile;
for (var i = input.Length - 8; i >= 0; i--)
{
if (BitConverter.ToUInt32(input, i) != POKE)
{
continue;
}
var keyIndex = BitConverter.ToInt32(input, i + 4);
if (!MemeKey.IsValidPokeKeyIndex(keyIndex))
{
continue;
}
memeLen = i;
memeIndex = (MemeKeyIndex)keyIndex;
break;
}
foreach (var len in new[] { memeLen, memeLen - 2 }) // Account for Pokédex QR Edge case
{
if (VerifyMemeData(input, out output, 0, len, memeIndex))
{
return(true);
}
if (VerifyMemeData(input, out output, 0, len, MemeKeyIndex.PokedexAndSaveFile))
{
return(true);
}
}
output = input;
return(false);
}
