/* $OpenBSD: arc4.c,v 1.1 2003/10/07 07:07:14 markus Exp $ */ /* * Copyright (c) 2003 Markus Friedl <markus@openbsd.org> * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include <sys/types.h> #include <crypto/arc4.h> #define RC4SWAP(x,y) \ do { \ u_int8_t t = ctx->state[x]; \ ctx->state[x] = ctx->state[y]; \ ctx->state[y] = t; \ } while(0) void rc4_keysetup(struct rc4_ctx *ctx, u_char *key, u_int32_t klen) { u_int8_t x, y; u_int32_t i; x = y = 0; for (i = 0; i < RC4STATE; i++) ctx->state[i] = i; for (i = 0; i < RC4STATE; i++) { y = (key[x] + ctx->state[i] + y) % RC4STATE; RC4SWAP(i, y); x = (x + 1) % klen; } ctx->x = ctx->y = 0; } void rc4_crypt(struct rc4_ctx *ctx, u_char *src, u_char *dst, u_int32_t len) { u_int32_t i; for (i = 0; i < len; i++) { ctx->x = (ctx->x + 1) % RC4STATE; ctx->y = (ctx->state[ctx->x] + ctx->y) % RC4STATE; RC4SWAP(ctx->x, ctx->y); dst[i] = src[i] ^ ctx->state[ (ctx->state[ctx->x] + ctx->state[ctx->y]) % RC4STATE]; } }