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