1 /* 2 * AES Key Wrap Algorithm (RFC3394) 3 * 4 * Copyright (c) 2003-2007, Jouni Malinen <j (at) w1.fi> 5 * 6 * This software may be distributed under the terms of the BSD license. 7 * See README for more details. 8 */ 9 10 #include "includes.h" 11 12 #include "common.h" 13 #include "aes.h" 14 #include "aes_wrap.h" 15 16 /** 17 * aes_wrap - Wrap keys with AES Key Wrap Algorithm (RFC3394) 18 * @kek: Key encryption key (KEK) 19 * @kek_len: Length of KEK in octets 20 * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16 21 * bytes 22 * @plain: Plaintext key to be wrapped, n * 64 bits 23 * @cipher: Wrapped key, (n + 1) * 64 bits 24 * Returns: 0 on success, -1 on failure 25 */ 26 int aes_wrap(const u8 *kek, size_t kek_len, int n, const u8 *plain, u8 *cipher) 27 { 28 u8 *a, *r, b[AES_BLOCK_SIZE]; 29 int i, j; 30 void *ctx; 31 unsigned int t; 32 33 a = cipher; 34 r = cipher + 8; 35 36 /* 1) Initialize variables. */ 37 os_memset(a, 0xa6, 8); 38 os_memcpy(r, plain, 8 * n); 39 40 ctx = aes_encrypt_init(kek, kek_len); 41 if (ctx == NULL) 42 return -1; 43 44 /* 2) Calculate intermediate values. 45 * For j = 0 to 5 46 * For i=1 to n 47 * B = AES(K, A | R[i]) 48 * A = MSB(64, B) ^ t where t = (n*j)+i 49 * R[i] = LSB(64, B) 50 */ 51 for (j = 0; j <= 5; j++) { 52 r = cipher + 8; 53 for (i = 1; i <= n; i++) { 54 os_memcpy(b, a, 8); 55 os_memcpy(b + 8, r, 8); 56 aes_encrypt(ctx, b, b); 57 os_memcpy(a, b, 8); 58 t = n * j + i; 59 a[7] ^= t; 60 a[6] ^= t >> 8; 61 a[5] ^= t >> 16; 62 a[4] ^= t >> 24; 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
