1 /* 2 * AES Key Wrap Algorithm (128-bit KEK) (RFC3394) 3 * 4 * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * Alternatively, this software may be distributed under the terms of BSD 11 * license. 12 * 13 * See README and COPYING for more details. 14 */ 15 16 #include "includes.h" 17 18 #include "common.h" 19 #include "aes.h" 20 #include "aes_wrap.h" 21 22 /** 23 * aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394) 24 * @kek: 16-octet Key encryption key (KEK) 25 * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16 26 * bytes 27 * @plain: Plaintext key to be wrapped, n * 64 bits 28 * @cipher: Wrapped key, (n + 1) * 64 bits 29 * Returns: 0 on success, -1 on failure 30 */ 31 int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher) 32 { 33 u8 *a, *r, b[16]; 34 int i, j; 35 void *ctx; 36 37 a = cipher; 38 r = cipher + 8; 39 40 /* 1) Initialize variables. */ 41 os_memset(a, 0xa6, 8); 42 os_memcpy(r, plain, 8 * n); 43 44 ctx = aes_encrypt_init(kek, 16); 45 if (ctx == NULL) 46 return -1; 47 48 /* 2) Calculate intermediate values. 49 * For j = 0 to 5 50 * For i=1 to n 51 * B = AES(K, A | R[i]) 52 * A = MSB(64, B) ^ t where t = (n*j)+i 53 * R[i] = LSB(64, B) 54 */ 55 for (j = 0; j <= 5; j++) { 56 r = cipher + 8; 57 for (i = 1; i <= n; i++) { 58 os_memcpy(b, a, 8); 59 os_memcpy(b + 8, r, 8); 60 aes_encrypt(ctx, b, b); 61 os_memcpy(a, b, 8); 62 a[7] ^= n * j + i; 63 os_memcpy(r, b + 8, 8); 64 r += 8; 65 } 66 } 67 aes_encrypt_deinit(ctx); 68 69 /* 3) Output the results. 70 * 71 * These are already in @cipher due to the location of temporary 72 * variables. 73 */ 74 75 return 0; 76 } 77