1 /*
2 * File: RijndaelCBCMAC.cpp
3 *
4 * Copyright (c) Freescale Semiconductor, Inc. All rights reserved.
5 * See included license file for license details.
6 */
7
8 #include "RijndaelCBCMAC.h"
9 #include "rijndael.h"
10 #include <assert.h>
11 #include "Logging.h"
12
13 void logHexArray(Logger::log_level_t level, const uint8_t * bytes, unsigned count);
14
15 //! \param key The key to use as the CBC-MAC secret.
16 //! \param iv Initialization vector. Defaults to zero if not provided.
RijndaelCBCMAC(const AESKey<128> & key,const uint8_t * iv)17 RijndaelCBCMAC::RijndaelCBCMAC(const AESKey<128> & key, const uint8_t * iv)
18 : m_key(key)
19 {
20 if (iv)
21 {
22 memcpy(m_mac, iv, sizeof(m_mac));
23 }
24 else
25 {
26 memset(m_mac, 0, sizeof(m_mac));
27 }
28 }
29
30 //! \param data Pointer to data to process.
31 //! \param length Number of bytes to process. Must be evenly divisible by #BLOCK_SIZE.
update(const uint8_t * data,unsigned length)32 void RijndaelCBCMAC::update(const uint8_t * data, unsigned length)
33 {
34 assert(length % BLOCK_SIZE == 0);
35 unsigned blocks = length / BLOCK_SIZE;
36 while (blocks--)
37 {
38 updateOneBlock(data);
39 data += BLOCK_SIZE;
40 }
41 }
42
43 //! It appears that some forms of CBC-MAC encrypt the final output block again in
44 //! order to protect against a plaintext attack. This method is a placeholder for
45 //! such an operation, but it currently does nothing.
finalize()46 void RijndaelCBCMAC::finalize()
47 {
48 }
49
50 //! On entry the current value of m_mac becomes the initialization vector
51 //! for the CBC encryption of this block. The output of the encryption then
52 //! becomes the new MAC, which is stored in m_mac.
updateOneBlock(const uint8_t * data)53 void RijndaelCBCMAC::updateOneBlock(const uint8_t * data)
54 {
55 Rijndael cipher;
56 cipher.init(Rijndael::CBC, Rijndael::Encrypt, m_key, Rijndael::Key16Bytes, m_mac);
57 cipher.blockEncrypt(data, BLOCK_SIZE * 8, m_mac); // size is in bits
58
59 // Log::log(Logger::DEBUG2, "CBC-MAC output block:\n");
60 // logHexArray(Logger::DEBUG2, (const uint8_t *)&m_mac, sizeof(m_mac));
61 }
62
63 /*!
64 * \brief Log an array of bytes as hex.
65 */
logHexArray(Logger::log_level_t level,const uint8_t * bytes,unsigned count)66 void logHexArray(Logger::log_level_t level, const uint8_t * bytes, unsigned count)
67 {
68 Log::SetOutputLevel leveler(level);
69 // Log::log(" ");
70 unsigned i;
71 for (i = 0; i < count; ++i, ++bytes)
72 {
73 if ((i % 16 == 0) && (i < count - 1))
74 {
75 if (i != 0)
76 {
77 Log::log("\n");
78 }
79 Log::log(" 0x%04x: ", i);
80 }
81 Log::log("%02x ", *bytes & 0xff);
82 }
83
84 Log::log("\n");
85 }
86
87