Annotation of sys/crypto/arc4.c, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: arc4.c,v 1.2 2007/07/24 19:35:20 damien Exp $ */
! 2: /*
! 3: * Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
! 4: *
! 5: * Permission to use, copy, modify, and distribute this software for any
! 6: * purpose with or without fee is hereby granted, provided that the above
! 7: * copyright notice and this permission notice appear in all copies.
! 8: *
! 9: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
! 10: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
! 11: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
! 12: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
! 13: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
! 14: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
! 15: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
! 16: */
! 17:
! 18: #include <sys/types.h>
! 19:
! 20: #include <crypto/arc4.h>
! 21:
! 22: #define RC4SWAP(x,y) \
! 23: do { \
! 24: u_int8_t t = ctx->state[x]; \
! 25: ctx->state[x] = ctx->state[y]; \
! 26: ctx->state[y] = t; \
! 27: } while(0)
! 28:
! 29: void
! 30: rc4_keysetup(struct rc4_ctx *ctx, u_char *key, u_int32_t klen)
! 31: {
! 32: u_int8_t x, y;
! 33: u_int32_t i;
! 34:
! 35: x = y = 0;
! 36: for (i = 0; i < RC4STATE; i++)
! 37: ctx->state[i] = i;
! 38: for (i = 0; i < RC4STATE; i++) {
! 39: y = (key[x] + ctx->state[i] + y) % RC4STATE;
! 40: RC4SWAP(i, y);
! 41: x = (x + 1) % klen;
! 42: }
! 43: ctx->x = ctx->y = 0;
! 44: }
! 45:
! 46: void
! 47: rc4_crypt(struct rc4_ctx *ctx, u_char *src, u_char *dst,
! 48: u_int32_t len)
! 49: {
! 50: u_int32_t i;
! 51:
! 52: for (i = 0; i < len; i++) {
! 53: ctx->x = (ctx->x + 1) % RC4STATE;
! 54: ctx->y = (ctx->state[ctx->x] + ctx->y) % RC4STATE;
! 55: RC4SWAP(ctx->x, ctx->y);
! 56: dst[i] = src[i] ^ ctx->state[
! 57: (ctx->state[ctx->x] + ctx->state[ctx->y]) % RC4STATE];
! 58: }
! 59: }
! 60:
! 61: void
! 62: rc4_skip(struct rc4_ctx *ctx, u_int32_t len)
! 63: {
! 64: for (; len > 0; len--) {
! 65: ctx->x = (ctx->x + 1) % RC4STATE;
! 66: ctx->y = (ctx->state[ctx->x] + ctx->y) % RC4STATE;
! 67: RC4SWAP(ctx->x, ctx->y);
! 68: }
! 69: }
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