| // 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_DESCRIPTION("ARC4 Cipher Algorithm"); |
| MODULE_LICENSE("GPL"); |