/src/botan/src/lib/mac/cmac/cmac.cpp
Line | Count | Source |
1 | | /* |
2 | | * CMAC |
3 | | * (C) 1999-2007,2014 Jack Lloyd |
4 | | * |
5 | | * Botan is released under the Simplified BSD License (see license.txt) |
6 | | */ |
7 | | |
8 | | #include <botan/internal/cmac.h> |
9 | | |
10 | | #include <botan/exceptn.h> |
11 | | #include <botan/mem_ops.h> |
12 | | #include <botan/internal/fmt.h> |
13 | | #include <botan/internal/poly_dbl.h> |
14 | | #include <botan/internal/stl_util.h> |
15 | | |
16 | | namespace Botan { |
17 | | |
18 | | /* |
19 | | * Update an CMAC Calculation |
20 | | */ |
21 | 0 | void CMAC::add_data(std::span<const uint8_t> input) { |
22 | 0 | const size_t bs = output_length(); |
23 | |
|
24 | 0 | const size_t initial_fill = std::min(m_buffer.size() - m_position, input.size()); |
25 | 0 | copy_mem(m_buffer.data() + m_position, input.data(), initial_fill); |
26 | |
|
27 | 0 | if(m_position + input.size() > bs) { |
28 | 0 | xor_buf(m_state, m_buffer, bs); |
29 | 0 | m_cipher->encrypt(m_state); |
30 | |
|
31 | 0 | BufferSlicer in(input); |
32 | 0 | in.skip(bs - m_position); |
33 | 0 | while(in.remaining() > bs) { |
34 | 0 | xor_buf(m_state, in.take(bs), bs); |
35 | 0 | m_cipher->encrypt(m_state); |
36 | 0 | } |
37 | |
|
38 | 0 | const auto remaining = in.take(in.remaining()); |
39 | 0 | copy_mem(m_buffer.data(), remaining.data(), remaining.size()); |
40 | 0 | m_position = remaining.size(); |
41 | 0 | } else { |
42 | 0 | m_position += input.size(); |
43 | 0 | } |
44 | 0 | } |
45 | | |
46 | | /* |
47 | | * Finalize an CMAC Calculation |
48 | | */ |
49 | 0 | void CMAC::final_result(std::span<uint8_t> mac) { |
50 | 0 | xor_buf(m_state, m_buffer, m_position); |
51 | |
|
52 | 0 | if(m_position == output_length()) { |
53 | 0 | xor_buf(m_state, m_B, output_length()); |
54 | 0 | } else { |
55 | 0 | m_state[m_position] ^= 0x80; |
56 | 0 | xor_buf(m_state, m_P, output_length()); |
57 | 0 | } |
58 | |
|
59 | 0 | m_cipher->encrypt(m_state); |
60 | |
|
61 | 0 | copy_mem(mac.data(), m_state.data(), output_length()); |
62 | |
|
63 | 0 | zeroise(m_state); |
64 | 0 | zeroise(m_buffer); |
65 | 0 | m_position = 0; |
66 | 0 | } |
67 | | |
68 | 0 | bool CMAC::has_keying_material() const { |
69 | 0 | return m_cipher->has_keying_material(); |
70 | 0 | } |
71 | | |
72 | | /* |
73 | | * CMAC Key Schedule |
74 | | */ |
75 | 0 | void CMAC::key_schedule(std::span<const uint8_t> key) { |
76 | 0 | clear(); |
77 | 0 | m_cipher->set_key(key); |
78 | 0 | m_cipher->encrypt(m_B); |
79 | 0 | poly_double_n(m_B.data(), m_B.size()); |
80 | 0 | poly_double_n(m_P.data(), m_B.data(), m_P.size()); |
81 | 0 | } |
82 | | |
83 | | /* |
84 | | * Clear memory of sensitive data |
85 | | */ |
86 | 0 | void CMAC::clear() { |
87 | 0 | m_cipher->clear(); |
88 | 0 | zeroise(m_state); |
89 | 0 | zeroise(m_buffer); |
90 | 0 | zeroise(m_B); |
91 | 0 | zeroise(m_P); |
92 | 0 | m_position = 0; |
93 | 0 | } |
94 | | |
95 | | /* |
96 | | * Return the name of this type |
97 | | */ |
98 | 0 | std::string CMAC::name() const { |
99 | 0 | return fmt("CMAC({})", m_cipher->name()); |
100 | 0 | } |
101 | | |
102 | | /* |
103 | | * Return a new_object of this object |
104 | | */ |
105 | 0 | std::unique_ptr<MessageAuthenticationCode> CMAC::new_object() const { |
106 | 0 | return std::make_unique<CMAC>(m_cipher->new_object()); |
107 | 0 | } |
108 | | |
109 | | /* |
110 | | * CMAC Constructor |
111 | | */ |
112 | 0 | CMAC::CMAC(std::unique_ptr<BlockCipher> cipher) : m_cipher(std::move(cipher)), m_block_size(m_cipher->block_size()) { |
113 | 0 | if(!poly_double_supported_size(m_block_size)) { |
114 | 0 | throw Invalid_Argument(fmt("CMAC cannot use the {} bit cipher {}", m_block_size * 8, m_cipher->name())); |
115 | 0 | } |
116 | | |
117 | 0 | m_state.resize(output_length()); |
118 | 0 | m_buffer.resize(output_length()); |
119 | 0 | m_B.resize(output_length()); |
120 | 0 | m_P.resize(output_length()); |
121 | 0 | m_position = 0; |
122 | 0 | } |
123 | | |
124 | | } // namespace Botan |