/* ** Command & Conquer Renegade(tm) ** Copyright 2025 Electronic Arts Inc. ** ** This program is free software: you can redistribute it and/or modify ** it under the terms of the GNU General Public License as published by ** the Free Software Foundation, either version 3 of the License, or ** (at your option) any later version. ** ** This program is distributed in the hope that it will be useful, ** but WITHOUT ANY WARRANTY; without even the implied warranty of ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ** GNU General Public License for more details. ** ** You should have received a copy of the GNU General Public License ** along with this program. If not, see . */ // // rc4.cpp // RC4 encryption / decryption // #include "rc4.h" #include static unsigned char RC4_Temp_Byte; #define RC4_SWAP_BYTE(a,b) RC4_Temp_Byte=a; a=b; b=RC4_Temp_Byte // // Don't rely on this to zero the key // RC4Class::RC4Class() { memset(Key.State, 0, 256); Key.X=0; Key.Y=0; } // // Setup the encryption key. This must be called before you encrypt/decrypt! // void RC4Class::Prepare_Key(const unsigned char *key_data_ptr, int key_data_len) { unsigned char index1; unsigned char index2; unsigned char *state; int counter; state = &Key.State[0]; for (counter = 0; counter < 256; counter++) state[counter] = (unsigned char)counter; Key.X = 0; Key.Y = 0; index1 = 0; index2 = 0; for (counter = 0; counter < 256; counter++) { index2 = (unsigned char)(key_data_ptr[index1] + state[counter] + index2); RC4_SWAP_BYTE(state[counter], state[index2]); index1 = (unsigned char)((index1 + 1) % key_data_len); } } // // RC4 in standard mode. // // This will XOR the buffer with the RC4 stream (like a one time pad). // void RC4Class::RC4(unsigned char *buffer_ptr, int buffer_len) { unsigned char x; unsigned char y; unsigned char *state; int counter; x = Key.X; y = Key.Y; state = &Key.State[0]; for (counter = 0; counter < buffer_len; counter++) { x++; y = (unsigned char)(y + state[x]); RC4_SWAP_BYTE(state[x], state[y]); buffer_ptr[counter] ^= state[(state[x] + state[y]) & 255]; } Key.X = x; Key.Y = y; }