rc4.c revision 59108
1271093Sbr 2271093Sbr/* 3271093Sbr * rc4.c 4271093Sbr * 5271093Sbr * Copyright (c) 1996-2000 Whistle Communications, Inc. 6271093Sbr * All rights reserved. 7271093Sbr * 8271093Sbr * Subject to the following obligations and disclaimer of warranty, use and 9271093Sbr * redistribution of this software, in source or object code forms, with or 10271093Sbr * without modifications are expressly permitted by Whistle Communications; 11271093Sbr * provided, however, that: 12271093Sbr * 1. Any and all reproductions of the source or object code must include the 13271093Sbr * copyright notice above and the following disclaimer of warranties; and 14271093Sbr * 2. No rights are granted, in any manner or form, to use Whistle 15271093Sbr * Communications, Inc. trademarks, including the mark "WHISTLE 16271093Sbr * COMMUNICATIONS" on advertising, endorsements, or otherwise except as 17271093Sbr * such appears in the above copyright notice or in the software. 18271093Sbr * 19271093Sbr * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 20271093Sbr * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 21271093Sbr * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 22271093Sbr * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 23271093Sbr * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 24271093Sbr * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 25271093Sbr * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 26271093Sbr * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 27271093Sbr * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 28271093Sbr * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 29271093Sbr * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 30271093Sbr * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 31271093Sbr * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 32271093Sbr * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33271093Sbr * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34271093Sbr * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 35271093Sbr * OF SUCH DAMAGE. 36271093Sbr * 37271093Sbr * $FreeBSD: head/sys/crypto/rc4/rc4.c 59108 2000-04-09 21:01:01Z archie $ 38271093Sbr */ 39271093Sbr 40271093Sbr#include <sys/types.h> 41271093Sbr#include <crypto/rc4/rc4.h> 42271093Sbr 43271093Sbrstatic __inline void 44271093Sbrswap_bytes(u_char *a, u_char *b) 45271093Sbr{ 46271093Sbr u_char temp; 47271093Sbr 48271093Sbr temp = *a; 49271093Sbr *a = *b; 50271093Sbr *b = temp; 51271093Sbr} 52271093Sbr 53271093Sbr/* 54271093Sbr * Initialize an RC4 state buffer using the supplied key, 55271093Sbr * which can have arbitrary length. 56271093Sbr */ 57271093Sbrvoid 58271093Sbrrc4_init(struct rc4_state *const state, const u_char *key, int keylen) 59271093Sbr{ 60271093Sbr u_char j; 61271093Sbr int i; 62271093Sbr 63271093Sbr /* Initialize state with identity permutation */ 64271093Sbr for (i = 0; i < 256; i++) 65271093Sbr state->perm[i] = (u_char)i; 66271093Sbr state->index1 = 0; 67271093Sbr state->index2 = 0; 68271093Sbr 69271093Sbr /* Randomize the permutation using key data */ 70271093Sbr for (j = i = 0; i < 256; i++) { 71271093Sbr j += state->perm[i] + key[i % keylen]; 72271186Sbr swap_bytes(&state->perm[i], &state->perm[j]); 73271186Sbr } 74271186Sbr} 75271186Sbr 76271186Sbr/* 77271186Sbr * Encrypt some data using the supplied RC4 state buffer. 78271186Sbr * The input and output buffers may be the same buffer. 79271186Sbr * Since RC4 is a stream cypher, this function is used 80271093Sbr * for both encryption and decryption. 81271093Sbr */ 82271093Sbrvoid 83271093Sbrrc4_crypt(struct rc4_state *const state, 84271093Sbr const u_char *inbuf, u_char *outbuf, int buflen) 85271093Sbr{ 86271093Sbr int i; 87271093Sbr u_char j; 88271093Sbr 89271093Sbr for (i = 0; i < buflen; i++) { 90271093Sbr 91271093Sbr /* Update modification indicies */ 92271093Sbr state->index1++; 93271093Sbr state->index2 += state->perm[state->index1]; 94271093Sbr 95271093Sbr /* Modify permutation */ 96271093Sbr swap_bytes(&state->perm[state->index1], 97271093Sbr &state->perm[state->index2]); 98271093Sbr 99271093Sbr /* Encrypt/decrypt next byte */ 100271093Sbr j = state->perm[state->index1] + state->perm[state->index2]; 101271093Sbr outbuf[i] = inbuf[i] ^ state->perm[j]; 102271093Sbr } 103271093Sbr} 104271093Sbr 105271093Sbr