1 // SPDX-License-Identifier: GPL-2.0-or-later 1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* 2 /*
3 * Cryptographic API 3 * Cryptographic API
4 * 4 *
5 * ARC4 Cipher Algorithm 5 * ARC4 Cipher Algorithm
6 * 6 *
7 * Jon Oberheide <jon@oberheide.org> 7 * Jon Oberheide <jon@oberheide.org>
8 */ 8 */
9 9
10 #include <crypto/arc4.h> 10 #include <crypto/arc4.h>
11 #include <linux/module.h> 11 #include <linux/module.h>
12 12
13 int arc4_setkey(struct arc4_ctx *ctx, const u8 13 int arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len)
14 { 14 {
15 int i, j = 0, k = 0; 15 int i, j = 0, k = 0;
16 16
17 ctx->x = 1; 17 ctx->x = 1;
18 ctx->y = 0; 18 ctx->y = 0;
19 19
20 for (i = 0; i < 256; i++) 20 for (i = 0; i < 256; i++)
21 ctx->S[i] = i; 21 ctx->S[i] = i;
22 22
23 for (i = 0; i < 256; i++) { 23 for (i = 0; i < 256; i++) {
24 u32 a = ctx->S[i]; 24 u32 a = ctx->S[i];
25 25
26 j = (j + in_key[k] + a) & 0xff 26 j = (j + in_key[k] + a) & 0xff;
27 ctx->S[i] = ctx->S[j]; 27 ctx->S[i] = ctx->S[j];
28 ctx->S[j] = a; 28 ctx->S[j] = a;
29 if (++k >= key_len) 29 if (++k >= key_len)
30 k = 0; 30 k = 0;
31 } 31 }
32 32
33 return 0; 33 return 0;
34 } 34 }
35 EXPORT_SYMBOL(arc4_setkey); 35 EXPORT_SYMBOL(arc4_setkey);
36 36
37 void arc4_crypt(struct arc4_ctx *ctx, u8 *out, 37 void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len)
38 { 38 {
39 u32 *const S = ctx->S; 39 u32 *const S = ctx->S;
40 u32 x, y, a, b; 40 u32 x, y, a, b;
41 u32 ty, ta, tb; 41 u32 ty, ta, tb;
42 42
43 if (len == 0) 43 if (len == 0)
44 return; 44 return;
45 45
46 x = ctx->x; 46 x = ctx->x;
47 y = ctx->y; 47 y = ctx->y;
48 48
49 a = S[x]; 49 a = S[x];
50 y = (y + a) & 0xff; 50 y = (y + a) & 0xff;
51 b = S[y]; 51 b = S[y];
52 52
53 do { 53 do {
54 S[y] = a; 54 S[y] = a;
55 a = (a + b) & 0xff; 55 a = (a + b) & 0xff;
56 S[x] = b; 56 S[x] = b;
57 x = (x + 1) & 0xff; 57 x = (x + 1) & 0xff;
58 ta = S[x]; 58 ta = S[x];
59 ty = (y + ta) & 0xff; 59 ty = (y + ta) & 0xff;
60 tb = S[ty]; 60 tb = S[ty];
61 *out++ = *in++ ^ S[a]; 61 *out++ = *in++ ^ S[a];
62 if (--len == 0) 62 if (--len == 0)
63 break; 63 break;
64 y = ty; 64 y = ty;
65 a = ta; 65 a = ta;
66 b = tb; 66 b = tb;
67 } while (true); 67 } while (true);
68 68
69 ctx->x = x; 69 ctx->x = x;
70 ctx->y = y; 70 ctx->y = y;
71 } 71 }
72 EXPORT_SYMBOL(arc4_crypt); 72 EXPORT_SYMBOL(arc4_crypt);
73 73
74 MODULE_DESCRIPTION("ARC4 Cipher Algorithm"); 74 MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
75 MODULE_LICENSE("GPL"); 75 MODULE_LICENSE("GPL");
76 76
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