1 /* 2 * AES-128 EAX 3 * 4 * Copyright (c) 2003-2007, Jouni Malinen <j (at) 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_128_eax_encrypt - AES-128 EAX mode encryption 24 * @key: Key for encryption (16 bytes) 25 * @nonce: Nonce for counter mode 26 * @nonce_len: Nonce length in bytes 27 * @hdr: Header data to be authenticity protected 28 * @hdr_len: Length of the header data bytes 29 * @data: Data to encrypt in-place 30 * @data_len: Length of data in bytes 31 * @tag: 16-byte tag value 32 * Returns: 0 on success, -1 on failure 33 */ 34 int aes_128_eax_encrypt(const u8 *key, const u8 *nonce, size_t nonce_len, 35 const u8 *hdr, size_t hdr_len, 36 u8 *data, size_t data_len, u8 *tag) 37 { 38 u8 *buf; 39 size_t buf_len; 40 u8 nonce_mac[AES_BLOCK_SIZE], hdr_mac[AES_BLOCK_SIZE], 41 data_mac[AES_BLOCK_SIZE]; 42 int i, ret = -1; 43 44 if (nonce_len > data_len) 45 buf_len = nonce_len; 46 else 47 buf_len = data_len; 48 if (hdr_len > buf_len) 49 buf_len = hdr_len; 50 buf_len += 16; 51 52 buf = os_malloc(buf_len); 53 if (buf == NULL) 54 return -1; 55 56 os_memset(buf, 0, 15); 57 58 buf[15] = 0; 59 os_memcpy(buf + 16, nonce, nonce_len); 60 if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac)) 61 goto fail; 62 63 buf[15] = 1; 64 os_memcpy(buf + 16, hdr, hdr_len); 65 if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac)) 66 goto fail; 67 68 if (aes_128_ctr_encrypt(key, nonce_mac, data, data_len)) 69 goto fail; 70 buf[15] = 2; 71 os_memcpy(buf + 16, data, data_len); 72 if (omac1_aes_128(key, buf, 16 + data_len, data_mac)) 73 goto fail; 74 75 for (i = 0; i < AES_BLOCK_SIZE; i++) 76 tag[i] = nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i]; 77 78 ret = 0; 79 fail: 80 os_free(buf); 81 82 return ret; 83 } 84 85 86 /** 87 * aes_128_eax_decrypt - AES-128 EAX mode decryption 88 * @key: Key for decryption (16 bytes) 89 * @nonce: Nonce for counter mode 90 * @nonce_len: Nonce length in bytes 91 * @hdr: Header data to be authenticity protected 92 * @hdr_len: Length of the header data bytes 93 * @data: Data to encrypt in-place 94 * @data_len: Length of data in bytes 95 * @tag: 16-byte tag value 96 * Returns: 0 on success, -1 on failure, -2 if tag does not match 97 */ 98 int aes_128_eax_decrypt(const u8 *key, const u8 *nonce, size_t nonce_len, 99 const u8 *hdr, size_t hdr_len, 100 u8 *data, size_t data_len, const u8 *tag) 101 { 102 u8 *buf; 103 size_t buf_len; 104 u8 nonce_mac[AES_BLOCK_SIZE], hdr_mac[AES_BLOCK_SIZE], 105 data_mac[AES_BLOCK_SIZE]; 106 int i; 107 108 if (nonce_len > data_len) 109 buf_len = nonce_len; 110 else 111 buf_len = data_len; 112 if (hdr_len > buf_len) 113 buf_len = hdr_len; 114 buf_len += 16; 115 116 buf = os_malloc(buf_len); 117 if (buf == NULL) 118 return -1; 119 120 os_memset(buf, 0, 15); 121 122 buf[15] = 0; 123 os_memcpy(buf + 16, nonce, nonce_len); 124 if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac)) { 125 os_free(buf); 126 return -1; 127 } 128 129 buf[15] = 1; 130 os_memcpy(buf + 16, hdr, hdr_len); 131 if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac)) { 132 os_free(buf); 133 return -1; 134 } 135 136 buf[15] = 2; 137 os_memcpy(buf + 16, data, data_len); 138 if (omac1_aes_128(key, buf, 16 + data_len, data_mac)) { 139 os_free(buf); 140 return -1; 141 } 142 143 os_free(buf); 144 145 for (i = 0; i < AES_BLOCK_SIZE; i++) { 146 if (tag[i] != (nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i])) 147 return -2; 148 } 149 150 return aes_128_ctr_encrypt(key, nonce_mac, data, data_len); 151 } 152
