cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

cifs_arc4.c (1137B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Cryptographic API
      4 *
      5 * ARC4 Cipher Algorithm
      6 *
      7 * Jon Oberheide <jon@oberheide.org>
      8 */
      9
     10#include <linux/module.h>
     11#include "arc4.h"
     12
     13MODULE_LICENSE("GPL");
     14
     15int cifs_arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len)
     16{
     17	int i, j = 0, k = 0;
     18
     19	ctx->x = 1;
     20	ctx->y = 0;
     21
     22	for (i = 0; i < 256; i++)
     23		ctx->S[i] = i;
     24
     25	for (i = 0; i < 256; i++) {
     26		u32 a = ctx->S[i];
     27
     28		j = (j + in_key[k] + a) & 0xff;
     29		ctx->S[i] = ctx->S[j];
     30		ctx->S[j] = a;
     31		if (++k >= key_len)
     32			k = 0;
     33	}
     34
     35	return 0;
     36}
     37EXPORT_SYMBOL_GPL(cifs_arc4_setkey);
     38
     39void cifs_arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len)
     40{
     41	u32 *const S = ctx->S;
     42	u32 x, y, a, b;
     43	u32 ty, ta, tb;
     44
     45	if (len == 0)
     46		return;
     47
     48	x = ctx->x;
     49	y = ctx->y;
     50
     51	a = S[x];
     52	y = (y + a) & 0xff;
     53	b = S[y];
     54
     55	do {
     56		S[y] = a;
     57		a = (a + b) & 0xff;
     58		S[x] = b;
     59		x = (x + 1) & 0xff;
     60		ta = S[x];
     61		ty = (y + ta) & 0xff;
     62		tb = S[ty];
     63		*out++ = *in++ ^ S[a];
     64		if (--len == 0)
     65			break;
     66		y = ty;
     67		a = ta;
     68		b = tb;
     69	} while (true);
     70
     71	ctx->x = x;
     72	ctx->y = y;
     73}
     74EXPORT_SYMBOL_GPL(cifs_arc4_crypt);