516 lines
11 KiB
C
516 lines
11 KiB
C
/*
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* AES-based functions
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*
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* - AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
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* - One-Key CBC MAC (OMAC1) hash with AES-128
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* - AES-128 CTR mode encryption
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* - AES-128 EAX mode encryption/decryption
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* - AES-128 CBC
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*
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* Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Alternatively, this software may be distributed under the terms of BSD
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* license.
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*
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* See README and COPYING for more details.
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*/
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#include "includes.h"
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#include "common.h"
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#include "aes_wrap.h"
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#include "crypto.h"
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#ifdef INTERNAL_AES
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#include "aes.c"
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#endif /* INTERNAL_AES */
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#ifndef CONFIG_NO_AES_WRAP
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/**
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* aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
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* @kek: 16-octet Key encryption key (KEK)
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* @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
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* bytes
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* @plain: Plaintext key to be wrapped, n * 64 bits
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* @cipher: Wrapped key, (n + 1) * 64 bits
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* Returns: 0 on success, -1 on failure
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*/
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int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher)
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{
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u8 *a, *r, b[16];
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int i, j;
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void *ctx;
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a = cipher;
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r = cipher + 8;
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/* 1) Initialize variables. */
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os_memset(a, 0xa6, 8);
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os_memcpy(r, plain, 8 * n);
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ctx = aes_encrypt_init(kek, 16);
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if (ctx == NULL)
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return -1;
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/* 2) Calculate intermediate values.
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* For j = 0 to 5
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* For i=1 to n
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* B = AES(K, A | R[i])
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* A = MSB(64, B) ^ t where t = (n*j)+i
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* R[i] = LSB(64, B)
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*/
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for (j = 0; j <= 5; j++) {
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r = cipher + 8;
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for (i = 1; i <= n; i++) {
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os_memcpy(b, a, 8);
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os_memcpy(b + 8, r, 8);
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aes_encrypt(ctx, b, b);
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os_memcpy(a, b, 8);
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a[7] ^= n * j + i;
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os_memcpy(r, b + 8, 8);
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r += 8;
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}
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}
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aes_encrypt_deinit(ctx);
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/* 3) Output the results.
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*
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* These are already in @cipher due to the location of temporary
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* variables.
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*/
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return 0;
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}
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#endif /* CONFIG_NO_AES_WRAP */
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/**
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* aes_unwrap - Unwrap key with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
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* @kek: Key encryption key (KEK)
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* @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
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* bytes
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* @cipher: Wrapped key to be unwrapped, (n + 1) * 64 bits
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* @plain: Plaintext key, n * 64 bits
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* Returns: 0 on success, -1 on failure (e.g., integrity verification failed)
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*/
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int aes_unwrap(const u8 *kek, int n, const u8 *cipher, u8 *plain)
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{
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u8 a[8], *r, b[16];
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int i, j;
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void *ctx;
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/* 1) Initialize variables. */
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os_memcpy(a, cipher, 8);
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r = plain;
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os_memcpy(r, cipher + 8, 8 * n);
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ctx = aes_decrypt_init(kek, 16);
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if (ctx == NULL)
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return -1;
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/* 2) Compute intermediate values.
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* For j = 5 to 0
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* For i = n to 1
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* B = AES-1(K, (A ^ t) | R[i]) where t = n*j+i
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* A = MSB(64, B)
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* R[i] = LSB(64, B)
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*/
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for (j = 5; j >= 0; j--) {
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r = plain + (n - 1) * 8;
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for (i = n; i >= 1; i--) {
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os_memcpy(b, a, 8);
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b[7] ^= n * j + i;
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os_memcpy(b + 8, r, 8);
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aes_decrypt(ctx, b, b);
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os_memcpy(a, b, 8);
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os_memcpy(r, b + 8, 8);
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r -= 8;
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}
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}
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aes_decrypt_deinit(ctx);
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/* 3) Output results.
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*
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* These are already in @plain due to the location of temporary
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* variables. Just verify that the IV matches with the expected value.
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*/
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for (i = 0; i < 8; i++) {
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if (a[i] != 0xa6)
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return -1;
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}
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return 0;
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}
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#define BLOCK_SIZE 16
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#ifndef CONFIG_NO_AES_OMAC1
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static void gf_mulx(u8 *pad)
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{
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int i, carry;
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carry = pad[0] & 0x80;
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for (i = 0; i < BLOCK_SIZE - 1; i++)
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pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
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pad[BLOCK_SIZE - 1] <<= 1;
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if (carry)
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pad[BLOCK_SIZE - 1] ^= 0x87;
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}
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/**
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* omac1_aes_128_vector - One-Key CBC MAC (OMAC1) hash with AES-128
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* @key: 128-bit key for the hash operation
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* @num_elem: Number of elements in the data vector
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* @addr: Pointers to the data areas
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* @len: Lengths of the data blocks
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* @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
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* Returns: 0 on success, -1 on failure
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*/
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int omac1_aes_128_vector(const u8 *key, size_t num_elem,
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const u8 *addr[], const size_t *len, u8 *mac)
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{
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void *ctx;
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u8 cbc[BLOCK_SIZE], pad[BLOCK_SIZE];
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const u8 *pos, *end;
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size_t i, e, left, total_len;
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ctx = aes_encrypt_init(key, 16);
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if (ctx == NULL)
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return -1;
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os_memset(cbc, 0, BLOCK_SIZE);
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total_len = 0;
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for (e = 0; e < num_elem; e++)
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total_len += len[e];
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left = total_len;
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e = 0;
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pos = addr[0];
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end = pos + len[0];
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while (left >= BLOCK_SIZE) {
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for (i = 0; i < BLOCK_SIZE; i++) {
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cbc[i] ^= *pos++;
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if (pos >= end) {
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e++;
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pos = addr[e];
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end = pos + len[e];
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}
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}
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if (left > BLOCK_SIZE)
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aes_encrypt(ctx, cbc, cbc);
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left -= BLOCK_SIZE;
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}
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os_memset(pad, 0, BLOCK_SIZE);
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aes_encrypt(ctx, pad, pad);
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gf_mulx(pad);
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if (left || total_len == 0) {
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for (i = 0; i < left; i++) {
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cbc[i] ^= *pos++;
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if (pos >= end) {
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e++;
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pos = addr[e];
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end = pos + len[e];
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}
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}
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cbc[left] ^= 0x80;
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gf_mulx(pad);
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}
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for (i = 0; i < BLOCK_SIZE; i++)
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pad[i] ^= cbc[i];
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aes_encrypt(ctx, pad, mac);
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aes_encrypt_deinit(ctx);
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return 0;
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}
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/**
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* omac1_aes_128 - One-Key CBC MAC (OMAC1) hash with AES-128 (aka AES-CMAC)
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* @key: 128-bit key for the hash operation
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* @data: Data buffer for which a MAC is determined
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* @data_len: Length of data buffer in bytes
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* @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
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* Returns: 0 on success, -1 on failure
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*
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* This is a mode for using block cipher (AES in this case) for authentication.
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* OMAC1 was standardized with the name CMAC by NIST in a Special Publication
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* (SP) 800-38B.
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*/
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int omac1_aes_128(const u8 *key, const u8 *data, size_t data_len, u8 *mac)
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{
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return omac1_aes_128_vector(key, 1, &data, &data_len, mac);
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}
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#endif /* CONFIG_NO_AES_OMAC1 */
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/**
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* aes_128_encrypt_block - Perform one AES 128-bit block operation
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* @key: Key for AES
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* @in: Input data (16 bytes)
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* @out: Output of the AES block operation (16 bytes)
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* Returns: 0 on success, -1 on failure
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*/
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int aes_128_encrypt_block(const u8 *key, const u8 *in, u8 *out)
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{
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void *ctx;
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ctx = aes_encrypt_init(key, 16);
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if (ctx == NULL)
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return -1;
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aes_encrypt(ctx, in, out);
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aes_encrypt_deinit(ctx);
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return 0;
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}
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#ifndef CONFIG_NO_AES_CTR
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/**
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* aes_128_ctr_encrypt - AES-128 CTR mode encryption
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* @key: Key for encryption (16 bytes)
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* @nonce: Nonce for counter mode (16 bytes)
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* @data: Data to encrypt in-place
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* @data_len: Length of data in bytes
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* Returns: 0 on success, -1 on failure
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*/
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int aes_128_ctr_encrypt(const u8 *key, const u8 *nonce,
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u8 *data, size_t data_len)
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{
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void *ctx;
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size_t j, len, left = data_len;
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int i;
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u8 *pos = data;
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u8 counter[BLOCK_SIZE], buf[BLOCK_SIZE];
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ctx = aes_encrypt_init(key, 16);
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if (ctx == NULL)
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return -1;
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os_memcpy(counter, nonce, BLOCK_SIZE);
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while (left > 0) {
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aes_encrypt(ctx, counter, buf);
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len = (left < BLOCK_SIZE) ? left : BLOCK_SIZE;
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for (j = 0; j < len; j++)
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pos[j] ^= buf[j];
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pos += len;
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left -= len;
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for (i = BLOCK_SIZE - 1; i >= 0; i--) {
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counter[i]++;
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if (counter[i])
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break;
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}
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}
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aes_encrypt_deinit(ctx);
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return 0;
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}
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#endif /* CONFIG_NO_AES_CTR */
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#ifndef CONFIG_NO_AES_EAX
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/**
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* aes_128_eax_encrypt - AES-128 EAX mode encryption
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* @key: Key for encryption (16 bytes)
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* @nonce: Nonce for counter mode
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* @nonce_len: Nonce length in bytes
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* @hdr: Header data to be authenticity protected
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* @hdr_len: Length of the header data bytes
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* @data: Data to encrypt in-place
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* @data_len: Length of data in bytes
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* @tag: 16-byte tag value
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* Returns: 0 on success, -1 on failure
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*/
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int aes_128_eax_encrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
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const u8 *hdr, size_t hdr_len,
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u8 *data, size_t data_len, u8 *tag)
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{
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u8 *buf;
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size_t buf_len;
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u8 nonce_mac[BLOCK_SIZE], hdr_mac[BLOCK_SIZE], data_mac[BLOCK_SIZE];
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int i;
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if (nonce_len > data_len)
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buf_len = nonce_len;
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else
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buf_len = data_len;
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if (hdr_len > buf_len)
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buf_len = hdr_len;
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buf_len += 16;
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buf = os_malloc(buf_len);
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if (buf == NULL)
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return -1;
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os_memset(buf, 0, 15);
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buf[15] = 0;
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os_memcpy(buf + 16, nonce, nonce_len);
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omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac);
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buf[15] = 1;
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os_memcpy(buf + 16, hdr, hdr_len);
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omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac);
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aes_128_ctr_encrypt(key, nonce_mac, data, data_len);
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buf[15] = 2;
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os_memcpy(buf + 16, data, data_len);
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omac1_aes_128(key, buf, 16 + data_len, data_mac);
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os_free(buf);
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for (i = 0; i < BLOCK_SIZE; i++)
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tag[i] = nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i];
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return 0;
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}
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/**
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* aes_128_eax_decrypt - AES-128 EAX mode decryption
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* @key: Key for decryption (16 bytes)
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* @nonce: Nonce for counter mode
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* @nonce_len: Nonce length in bytes
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* @hdr: Header data to be authenticity protected
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* @hdr_len: Length of the header data bytes
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* @data: Data to encrypt in-place
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* @data_len: Length of data in bytes
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* @tag: 16-byte tag value
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* Returns: 0 on success, -1 on failure, -2 if tag does not match
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*/
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int aes_128_eax_decrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
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const u8 *hdr, size_t hdr_len,
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u8 *data, size_t data_len, const u8 *tag)
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{
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u8 *buf;
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size_t buf_len;
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u8 nonce_mac[BLOCK_SIZE], hdr_mac[BLOCK_SIZE], data_mac[BLOCK_SIZE];
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int i;
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if (nonce_len > data_len)
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buf_len = nonce_len;
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else
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buf_len = data_len;
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if (hdr_len > buf_len)
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buf_len = hdr_len;
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buf_len += 16;
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buf = os_malloc(buf_len);
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if (buf == NULL)
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return -1;
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os_memset(buf, 0, 15);
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buf[15] = 0;
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os_memcpy(buf + 16, nonce, nonce_len);
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omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac);
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buf[15] = 1;
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os_memcpy(buf + 16, hdr, hdr_len);
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omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac);
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buf[15] = 2;
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os_memcpy(buf + 16, data, data_len);
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omac1_aes_128(key, buf, 16 + data_len, data_mac);
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os_free(buf);
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for (i = 0; i < BLOCK_SIZE; i++) {
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if (tag[i] != (nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i]))
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return -2;
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}
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aes_128_ctr_encrypt(key, nonce_mac, data, data_len);
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return 0;
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}
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#endif /* CONFIG_NO_AES_EAX */
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#ifndef CONFIG_NO_AES_CBC
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/**
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* aes_128_cbc_encrypt - AES-128 CBC encryption
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* @key: Encryption key
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* @iv: Encryption IV for CBC mode (16 bytes)
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* @data: Data to encrypt in-place
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* @data_len: Length of data in bytes (must be divisible by 16)
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* Returns: 0 on success, -1 on failure
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*/
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int aes_128_cbc_encrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
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{
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void *ctx;
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u8 cbc[BLOCK_SIZE];
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u8 *pos = data;
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int i, j, blocks;
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ctx = aes_encrypt_init(key, 16);
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if (ctx == NULL)
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return -1;
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os_memcpy(cbc, iv, BLOCK_SIZE);
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blocks = data_len / BLOCK_SIZE;
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for (i = 0; i < blocks; i++) {
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for (j = 0; j < BLOCK_SIZE; j++)
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cbc[j] ^= pos[j];
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aes_encrypt(ctx, cbc, cbc);
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os_memcpy(pos, cbc, BLOCK_SIZE);
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pos += BLOCK_SIZE;
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}
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aes_encrypt_deinit(ctx);
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return 0;
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}
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/**
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* aes_128_cbc_decrypt - AES-128 CBC decryption
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* @key: Decryption key
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* @iv: Decryption IV for CBC mode (16 bytes)
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* @data: Data to decrypt in-place
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* @data_len: Length of data in bytes (must be divisible by 16)
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* Returns: 0 on success, -1 on failure
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*/
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int aes_128_cbc_decrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
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{
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void *ctx;
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u8 cbc[BLOCK_SIZE], tmp[BLOCK_SIZE];
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u8 *pos = data;
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int i, j, blocks;
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ctx = aes_decrypt_init(key, 16);
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if (ctx == NULL)
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return -1;
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os_memcpy(cbc, iv, BLOCK_SIZE);
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blocks = data_len / BLOCK_SIZE;
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for (i = 0; i < blocks; i++) {
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os_memcpy(tmp, pos, BLOCK_SIZE);
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aes_decrypt(ctx, pos, pos);
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for (j = 0; j < BLOCK_SIZE; j++)
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pos[j] ^= cbc[j];
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os_memcpy(cbc, tmp, BLOCK_SIZE);
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pos += BLOCK_SIZE;
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}
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aes_decrypt_deinit(ctx);
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return 0;
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}
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#endif /* CONFIG_NO_AES_CBC */
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