1 2 /* 3 * rc4.c 4 * 5 * Copyright (c) 1996-2000 Whistle Communications, Inc. 6 * All rights reserved. 7 * 8 * Subject to the following obligations and disclaimer of warranty, use and 9 * redistribution of this software, in source or object code forms, with or 10 * without modifications are expressly permitted by Whistle Communications; 11 * provided, however, that: 12 * 1. Any and all reproductions of the source or object code must include the 13 * copyright notice above and the following disclaimer of warranties; and 14 * 2. No rights are granted, in any manner or form, to use Whistle 15 * Communications, Inc. trademarks, including the mark "WHISTLE 16 * COMMUNICATIONS" on advertising, endorsements, or otherwise except as 17 * such appears in the above copyright notice or in the software. 18 * 19 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 20 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 21 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 22 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 23 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 24 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 25 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 26 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 27 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 28 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 29 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 30 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 31 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 35 * OF SUCH DAMAGE. 36 * 37 * $FreeBSD: src/sys/crypto/rc4/rc4.c,v 1.2.2.1 2000/04/18 04:48:31 archie Exp $ 38 */ 39 40 #include <sys/types.h> 41 #include <crypto/rc4/rc4.h> 42 43 static __inline void 44 swap_bytes(u_char *a, u_char *b) 45 { 46 u_char temp; 47 48 temp = *a; 49 *a = *b; 50 *b = temp; 51 } 52 53 /* 54 * Initialize an RC4 state buffer using the supplied key, 55 * which can have arbitrary length. 56 */ 57 void 58 rc4_init(struct rc4_state *const state, const u_char *key, int keylen) 59 { 60 u_char j; 61 int i; 62 63 /* Initialize state with identity permutation */ 64 for (i = 0; i < 256; i++) 65 state->perm[i] = (u_char)i; 66 state->index1 = 0; 67 state->index2 = 0; 68 69 /* Randomize the permutation using key data */ 70 for (j = i = 0; i < 256; i++) { 71 j += state->perm[i] + key[i % keylen]; 72 swap_bytes(&state->perm[i], &state->perm[j]); 73 } 74 } 75 76 /* 77 * Encrypt some data using the supplied RC4 state buffer. 78 * The input and output buffers may be the same buffer. 79 * Since RC4 is a stream cypher, this function is used 80 * for both encryption and decryption. 81 */ 82 void 83 rc4_crypt(struct rc4_state *const state, 84 const u_char *inbuf, u_char *outbuf, int buflen) 85 { 86 int i; 87 u_char j; 88 89 for (i = 0; i < buflen; i++) { 90 91 /* Update modification indicies */ 92 state->index1++; 93 state->index2 += state->perm[state->index1]; 94 95 /* Modify permutation */ 96 swap_bytes(&state->perm[state->index1], 97 &state->perm[state->index2]); 98 99 /* Encrypt/decrypt next byte */ 100 j = state->perm[state->index1] + state->perm[state->index2]; 101 outbuf[i] = inbuf[i] ^ state->perm[j]; 102 } 103 } 104 105