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 /* * AES Key Wrap Algorithm (128-bit KEK) (RFC3394) * * Copyright (c) 2003-2007, Jouni Malinen * * This software may be distributed under the terms of the BSD license. * See README for more details. */ #include "includes.h" #include "common.h" #include "aes.h" #include "aes_wrap.h" /** * aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394) * @kek: 16-octet Key encryption key (KEK) * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16 * bytes * @plain: Plaintext key to be wrapped, n * 64 bits * @cipher: Wrapped key, (n + 1) * 64 bits * Returns: 0 on success, -1 on failure */ int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher) { u8 *a, *r, b[16]; int i, j; void *ctx; a = cipher; r = cipher + 8; /* 1) Initialize variables. */ os_memset(a, 0xa6, 8); os_memcpy(r, plain, 8 * n); ctx = aes_encrypt_init(kek, 16); if (ctx == NULL) return -1; /* 2) Calculate intermediate values. * For j = 0 to 5 * For i=1 to n * B = AES(K, A | R[i]) * A = MSB(64, B) ^ t where t = (n*j)+i * R[i] = LSB(64, B) */ for (j = 0; j <= 5; j++) { r = cipher + 8; for (i = 1; i <= n; i++) { os_memcpy(b, a, 8); os_memcpy(b + 8, r, 8); aes_encrypt(ctx, b, b); os_memcpy(a, b, 8); a[7] ^= n * j + i; os_memcpy(r, b + 8, 8); r += 8; } } aes_encrypt_deinit(ctx); /* 3) Output the results. * * These are already in @cipher due to the location of temporary * variables. */ return 0; }