// SPDX-License-Identifier: GPL-2.0-or-later | |
/* | |
* Cryptographic API | |
* | |
* ARC4 Cipher Algorithm | |
* | |
* Jon Oberheide <jon@oberheide.org> | |
*/ | |
#include <crypto/arc4.h> | |
#include <linux/module.h> | |
int arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len) | |
{ | |
int i, j = 0, k = 0; | |
ctx->x = 1; | |
ctx->y = 0; | |
for (i = 0; i < 256; i++) | |
ctx->S[i] = i; | |
for (i = 0; i < 256; i++) { | |
u32 a = ctx->S[i]; | |
j = (j + in_key[k] + a) & 0xff; | |
ctx->S[i] = ctx->S[j]; | |
ctx->S[j] = a; | |
if (++k >= key_len) | |
k = 0; | |
} | |
return 0; | |
} | |
EXPORT_SYMBOL(arc4_setkey); | |
void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len) | |
{ | |
u32 *const S = ctx->S; | |
u32 x, y, a, b; | |
u32 ty, ta, tb; | |
if (len == 0) | |
return; | |
x = ctx->x; | |
y = ctx->y; | |
a = S[x]; | |
y = (y + a) & 0xff; | |
b = S[y]; | |
do { | |
S[y] = a; | |
a = (a + b) & 0xff; | |
S[x] = b; | |
x = (x + 1) & 0xff; | |
ta = S[x]; | |
ty = (y + ta) & 0xff; | |
tb = S[ty]; | |
*out++ = *in++ ^ S[a]; | |
if (--len == 0) | |
break; | |
y = ty; | |
a = ta; | |
b = tb; | |
} while (true); | |
ctx->x = x; | |
ctx->y = y; | |
} | |
EXPORT_SYMBOL(arc4_crypt); | |
MODULE_LICENSE("GPL"); |