1 /* 2 * AES-128 EAX 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_128_eax_encrypt - AES-128 EAX mode encryption 18 * @key: Key for encryption (16 bytes) 19 * @nonce: Nonce for counter mode 20 * @nonce_len: Nonce length in bytes 21 * @hdr: Header data to be authenticity protected 22 * @hdr_len: Length of the header data bytes 23 * @data: Data to encrypt in-place 24 * @data_len: Length of data in bytes 25 * @tag: 16-byte tag value 26 * Returns: 0 on success, -1 on failure 27 */ 28 int aes_128_eax_encrypt(const u8 *key, const u8 *nonce, size_t nonce_len, 29 const u8 *hdr, size_t hdr_len, 30 u8 *data, size_t data_len, u8 *tag) 31 { 32 u8 *buf; 33 size_t buf_len; 34 u8 nonce_mac[AES_BLOCK_SIZE], hdr_mac[AES_BLOCK_SIZE], 35 data_mac[AES_BLOCK_SIZE]; 36 int i, ret = -1; 37 38 if (nonce_len > data_len) 39 buf_len = nonce_len; 40 else 41 buf_len = data_len; 42 if (hdr_len > buf_len) 43 buf_len = hdr_len; 44 buf_len += 16; 45 46 buf = os_malloc(buf_len); 47 if (buf == NULL) 48 return -1; 49 50 os_memset(buf, 0, 15); 51 52 buf[15] = 0; 53 os_memcpy(buf + 16, nonce, nonce_len); 54 if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac)) 55 goto fail; 56 57 buf[15] = 1; 58 os_memcpy(buf + 16, hdr, hdr_len); 59 if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac)) 60 goto fail; 61 62 if (aes_128_ctr_encrypt(key, nonce_mac, data, data_len)) 63 goto fail; 64 buf[15] = 2; 65 os_memcpy(buf + 16, data, data_len); 66 if (omac1_aes_128(key, buf, 16 + data_len, data_mac)) 67 goto fail; 68 69 for (i = 0; i < AES_BLOCK_SIZE; i++) 70 tag[i] = nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i]; 71 72 ret = 0; 73 fail: 74 os_free(buf); 75 76 return ret; 77 } 78 79 80 /** 81 * aes_128_eax_decrypt - AES-128 EAX mode decryption 82 * @key: Key for decryption (16 bytes) 83 * @nonce: Nonce for counter mode 84 * @nonce_len: Nonce length in bytes 85 * @hdr: Header data to be authenticity protected 86 * @hdr_len: Length of the header data bytes 87 * @data: Data to encrypt in-place 88 * @data_len: Length of data in bytes 89 * @tag: 16-byte tag value 90 * Returns: 0 on success, -1 on failure, -2 if tag does not match 91 */ 92 int aes_128_eax_decrypt(const u8 *key, const u8 *nonce, size_t nonce_len, 93 const u8 *hdr, size_t hdr_len, 94 u8 *data, size_t data_len, const u8 *tag) 95 { 96 u8 *buf; 97 size_t buf_len; 98 u8 nonce_mac[AES_BLOCK_SIZE], hdr_mac[AES_BLOCK_SIZE], 99 data_mac[AES_BLOCK_SIZE]; 100 int i; 101 102 if (nonce_len > data_len) 103 buf_len = nonce_len; 104 else 105 buf_len = data_len; 106 if (hdr_len > buf_len) 107 buf_len = hdr_len; 108 buf_len += 16; 109 110 buf = os_malloc(buf_len); 111 if (buf == NULL) 112 return -1; 113 114 os_memset(buf, 0, 15); 115 116 buf[15] = 0; 117 os_memcpy(buf + 16, nonce, nonce_len); 118 if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac)) { 119 os_free(buf); 120 return -1; 121 } 122 123 buf[15] = 1; 124 os_memcpy(buf + 16, hdr, hdr_len); 125 if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac)) { 126 os_free(buf); 127 return -1; 128 } 129 130 buf[15] = 2; 131 os_memcpy(buf + 16, data, data_len); 132 if (omac1_aes_128(key, buf, 16 + data_len, data_mac)) { 133 os_free(buf); 134 return -1; 135 } 136 137 os_free(buf); 138 139 for (i = 0; i < AES_BLOCK_SIZE; i++) { 140 if (tag[i] != (nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i])) 141 return -2; 142 } 143 144 return aes_128_ctr_encrypt(key, nonce_mac, data, data_len); 145 } 146
