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