/// <summary>
/// This method decrypts the specified data using the algorithm. This method should be used in checking the
/// inputted password from the client, encrypted and passed in the authentication request packet.
/// </summary>
/// <param name="input">The inputted buffer to be decrypted.</param>
public unsafe void Decrypt(byte[] input)
{
for (int index = 0; index < input.Length; index++)
{
// Is the algorithm done decrypting data?
if (input[index] == 0)
{
fixed(byte *ptr = input)
NativeFunctionCalls.memset(ptr + index, 0, input.Length - index);
return;
}
// Decrypt the byte at the current offset:
byte position = _keyBuffer[input[index] * 2];
if (position > 0x80)
{
// Entered using the "SHIFT" key:
position = (byte)(_keyBuffer[input[index] * 2] - 0x80);
input[index] = _decryptionSubstitutionBox[position];
}
else
{
input[index] = _decryptionSubstitutionBox[position];
if (input[index] >= 0x41 && input[index] <= 90)
{
input[index] = (byte)(input[index] + 0x20);
}
}
}
}
/// <summary>
/// Blowfish is a keyed, symmetric block cipher, designed in 1993 by Bruce Schneier and included in a large
/// number of cipher suites and encryption products. Blowfish provides a good encryption rate in software and no
/// effective cryptanalysis of it has been found to date. However, the Advanced Encryption Standard now receives
/// more attention. Schneier designed Blowfish as a general-purpose algorithm, intended as an alternative to the
/// aging DES and free of the problems and constraints associated with other algorithms. Schneier has stated that,
/// "Blowfish is unpatented, and will remain so in all countries. The algorithm is hereby placed in the public
/// domain, and can be freely used by anyone." The implementation type in use is CFB64.
/// </summary>
public BlowfishCipher()
{
_encryptionLock = new object();
_decryptionLock = new object();
_encryptionIncrementor = 0;
_decryptionIncrementor = 0;
_encryptionIV = (byte *)NativeFunctionCalls.malloc(BF_BLOCK_SIZE);
_decryptionIV = (byte *)NativeFunctionCalls.malloc(BF_BLOCK_SIZE);
NativeFunctionCalls.memset(_encryptionIV, 0, BF_BLOCK_SIZE);
NativeFunctionCalls.memset(_decryptionIV, 0, BF_BLOCK_SIZE);
KeySchedule(InitialKey);
}
