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| // 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");
|
|
