1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Cryptographic API 4 * 5 * ARC4 Cipher Algorithm 6 * 7 * Jon Oberheide <jon@oberheide.org> 8 */ 9 10 #include <linux/module.h> 11 #include "arc4.h" 12 13 MODULE_LICENSE("GPL"); 14 15 int cifs_arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len) 16 { 17 int i, j = 0, k = 0; 18 19 ctx->x = 1; 20 ctx->y = 0; 21 22 for (i = 0; i < 256; i++) 23 ctx->S[i] = i; 24 25 for (i = 0; i < 256; i++) { 26 u32 a = ctx->S[i]; 27 28 j = (j + in_key[k] + a) & 0xff; 29 ctx->S[i] = ctx->S[j]; 30 ctx->S[j] = a; 31 if (++k >= key_len) 32 k = 0; 33 } 34 35 return 0; 36 } 37 EXPORT_SYMBOL_GPL(cifs_arc4_setkey); 38 39 void cifs_arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len) 40 { 41 u32 *const S = ctx->S; 42 u32 x, y, a, b; 43 u32 ty, ta, tb; 44 45 if (len == 0) 46 return; 47 48 x = ctx->x; 49 y = ctx->y; 50 51 a = S[x]; 52 y = (y + a) & 0xff; 53 b = S[y]; 54 55 do { 56 S[y] = a; 57 a = (a + b) & 0xff; 58 S[x] = b; 59 x = (x + 1) & 0xff; 60 ta = S[x]; 61 ty = (y + ta) & 0xff; 62 tb = S[ty]; 63 *out++ = *in++ ^ S[a]; 64 if (--len == 0) 65 break; 66 y = ty; 67 a = ta; 68 b = tb; 69 } while (true); 70 71 ctx->x = x; 72 ctx->y = y; 73 } 74 EXPORT_SYMBOL_GPL(cifs_arc4_crypt); 75