Botan 2.13.0 Crypto and TLS for C++11

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ctr.cpp
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1 /*
2 * Counter mode
3 * (C) 1999-2011,2014 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7
8 #include <botan/ctr.h>
9 #include <botan/exceptn.h>
10 #include <botan/loadstor.h>
11 #include <botan/internal/bit_ops.h>
12
13 namespace Botan {
14
15 CTR_BE::CTR_BE(BlockCipher* ciph) :
16 m_cipher(ciph),
17 m_block_size(m_cipher->block_size()),
18 m_ctr_size(m_block_size),
19 m_ctr_blocks(m_cipher->parallel_bytes() / m_block_size),
20 m_counter(m_cipher->parallel_bytes()),
21 m_pad(m_counter.size()),
22 m_pad_pos(0)
23 {
24 }
25
26 CTR_BE::CTR_BE(BlockCipher* cipher, size_t ctr_size) :
27 m_cipher(cipher),
28 m_block_size(m_cipher->block_size()),
29 m_ctr_size(ctr_size),
30 m_ctr_blocks(m_cipher->parallel_bytes() / m_block_size),
31 m_counter(m_cipher->parallel_bytes()),
32 m_pad(m_counter.size()),
33 m_pad_pos(0)
34 {
35 BOTAN_ARG_CHECK(m_ctr_size >= 4 && m_ctr_size <= m_block_size,
36 "Invalid CTR-BE counter size");
37 }
38
39 void CTR_BE::clear()
40 {
41 m_cipher->clear();
42 zeroise(m_pad);
43 zeroise(m_counter);
44 zap(m_iv);
45 m_pad_pos = 0;
46 }
47
48 size_t CTR_BE::default_iv_length() const
49 {
50 return m_block_size;
51 }
52
53 bool CTR_BE::valid_iv_length(size_t iv_len) const
54 {
55 return (iv_len <= m_block_size);
56 }
57
58 Key_Length_Specification CTR_BE::key_spec() const
59 {
60 return m_cipher->key_spec();
61 }
62
63 CTR_BE* CTR_BE::clone() const
64 {
65 return new CTR_BE(m_cipher->clone(), m_ctr_size);
66 }
67
68 void CTR_BE::key_schedule(const uint8_t key[], size_t key_len)
69 {
70 m_cipher->set_key(key, key_len);
71
72 // Set a default all-zeros IV
73 set_iv(nullptr, 0);
74 }
75
76 std::string CTR_BE::name() const
77 {
78 if(m_ctr_size == m_block_size)
79 return ("CTR-BE(" + m_cipher->name() + ")");
80 else
81 return ("CTR-BE(" + m_cipher->name() + "," + std::to_string(m_ctr_size) + ")");
82
83 }
84
85 void CTR_BE::cipher(const uint8_t in[], uint8_t out[], size_t length)
86 {
87 verify_key_set(m_iv.empty() == false);
88
89 const uint8_t* pad_bits = &m_pad[0];
90 const size_t pad_size = m_pad.size();
91
92 if(m_pad_pos > 0)
93 {
94 const size_t avail = pad_size - m_pad_pos;
95 const size_t take = std::min(length, avail);
96 xor_buf(out, in, pad_bits + m_pad_pos, take);
97 length -= take;
98 in += take;
99 out += take;
100 m_pad_pos += take;
101
102 if(take == avail)
103 {
104 add_counter(m_ctr_blocks);
105 m_cipher->encrypt_n(m_counter.data(), m_pad.data(), m_ctr_blocks);
106 m_pad_pos = 0;
107 }
108 }
109
110 while(length >= pad_size)
111 {
112 xor_buf(out, in, pad_bits, pad_size);
113 length -= pad_size;
114 in += pad_size;
115 out += pad_size;
116
117 add_counter(m_ctr_blocks);
118 m_cipher->encrypt_n(m_counter.data(), m_pad.data(), m_ctr_blocks);
119 }
120
121 xor_buf(out, in, pad_bits, length);
122 m_pad_pos += length;
123 }
124
125 void CTR_BE::set_iv(const uint8_t iv[], size_t iv_len)
126 {
127 if(!valid_iv_length(iv_len))
128 throw Invalid_IV_Length(name(), iv_len);
129
130 m_iv.resize(m_block_size);
131 zeroise(m_iv);
132 buffer_insert(m_iv, 0, iv, iv_len);
133
134 seek(0);
135 }
136
137 void CTR_BE::add_counter(const uint64_t counter)
138 {
139 const size_t ctr_size = m_ctr_size;
140 const size_t ctr_blocks = m_ctr_blocks;
141 const size_t BS = m_block_size;
142
143 if(ctr_size == 4)
144 {
145 const size_t off = (BS - 4);
146 const uint32_t low32 = static_cast<uint32_t>(counter + load_be<uint32_t>(&m_counter[off], 0));
147
148 for(size_t i = 0; i != ctr_blocks; ++i)
149 {
150 store_be(uint32_t(low32 + i), &m_counter[i*BS+off]);
151 }
152 }
153 else if(ctr_size == 8)
154 {
155 const size_t off = (BS - 8);
156 const uint64_t low64 = counter + load_be<uint64_t>(&m_counter[off], 0);
157
158 for(size_t i = 0; i != ctr_blocks; ++i)
159 {
160 store_be(uint64_t(low64 + i), &m_counter[i*BS+off]);
161 }
162 }
163 else if(ctr_size == 16)
164 {
165 const size_t off = (BS - 16);
166 uint64_t b0 = load_be<uint64_t>(&m_counter[off], 0);
167 uint64_t b1 = load_be<uint64_t>(&m_counter[off], 1);
168 b1 += counter;
169 b0 += (b1 < counter) ? 1 : 0; // carry
170
171 for(size_t i = 0; i != ctr_blocks; ++i)
172 {
173 store_be(b0, &m_counter[i*BS+off]);
174 store_be(b1, &m_counter[i*BS+off+8]);
175 b1 += 1;
176 b0 += (b1 == 0); // carry
177 }
178 }
179 else
180 {
181 for(size_t i = 0; i != ctr_blocks; ++i)
182 {
183 uint64_t local_counter = counter;
184 uint16_t carry = static_cast<uint8_t>(local_counter);
185 for(size_t j = 0; (carry || local_counter) && j != ctr_size; ++j)
186 {
187 const size_t off = i*BS + (BS-1-j);
188 const uint16_t cnt = static_cast<uint16_t>(m_counter[off]) + carry;
189 m_counter[off] = static_cast<uint8_t>(cnt);
190 local_counter = (local_counter >> 8);
191 carry = (cnt >> 8) + static_cast<uint8_t>(local_counter);
192 }
193 }
194 }
195 }
196
197 void CTR_BE::seek(uint64_t offset)
198 {
199 verify_key_set(m_iv.empty() == false);
200
201 const uint64_t base_counter = m_ctr_blocks * (offset / m_counter.size());
202
203 zeroise(m_counter);
204 buffer_insert(m_counter, 0, m_iv);
205
206 const size_t BS = m_block_size;
207
208 // Set m_counter blocks to IV, IV + 1, ... IV + n
209
210 if(m_ctr_size == 4 && BS >= 8)
211 {
212 const uint32_t low32 = load_be<uint32_t>(&m_counter[BS-4], 0);
213
214 if(m_ctr_blocks >= 4 && is_power_of_2(m_ctr_blocks))
215 {
216 size_t written = 1;
217 while(written < m_ctr_blocks)
218 {
219 copy_mem(&m_counter[written*BS], &m_counter[0], BS*written);
220 written *= 2;
221 }
222 }
223 else
224 {
225 for(size_t i = 1; i != m_ctr_blocks; ++i)
226 {
227 copy_mem(&m_counter[i*BS], &m_counter[0], BS - 4);
228 }
229 }
230
231 for(size_t i = 1; i != m_ctr_blocks; ++i)
232 {
233 const uint32_t c = static_cast<uint32_t>(low32 + i);
234 store_be(c, &m_counter[(BS-4)+i*BS]);
235 }
236 }
237 else
238 {
239 // do everything sequentially:
240 for(size_t i = 1; i != m_ctr_blocks; ++i)
241 {
242 buffer_insert(m_counter, i*BS, &m_counter[(i-1)*BS], BS);
243
244 for(size_t j = 0; j != m_ctr_size; ++j)
245 if(++m_counter[i*BS + (BS - 1 - j)])
246 break;
247 }
248 }
249
250 if(base_counter > 0)
251 add_counter(base_counter);
252
253 m_cipher->encrypt_n(m_counter.data(), m_pad.data(), m_ctr_blocks);
254 m_pad_pos = offset % m_counter.size();
255 }
256 }
m_cipher
CCCryptorRef m_cipher
Definition: commoncrypto_mode.cpp:50
Botan::zap
void zap(std::vector< T, Alloc > &vec)
Definition: secmem.h:170
Botan::carry
void carry(int64_t &h0, int64_t &h1)
Definition: ed25519_internal.h:32
Botan::store_be
void store_be(uint16_t in, uint8_t out[2])
Definition: loadstor.h:438
Botan::Invalid_IV_Length
Definition: exceptn.h:161
Botan::load_be< uint32_t >
uint32_t load_be< uint32_t >(const uint8_t in[], size_t off)
Definition: loadstor.h:179
Botan::Key_Length_Specification
Definition: key_spec.h:18
Botan::CTR_BE
Definition: ctr.h:21
Botan::CTR_BE::default_iv_length
size_t default_iv_length() const override
Definition: ctr.cpp:48
Botan::CTR_BE::name
std::string name() const override
Definition: ctr.cpp:76
Botan::ASN1::to_string
std::string to_string(const BER_Object &obj)
Definition: asn1_obj.cpp:213
Botan::load_be< uint64_t >
uint64_t load_be< uint64_t >(const uint8_t in[], size_t off)
Definition: loadstor.h:217
Botan::CTR_BE::seek
void seek(uint64_t offset) override
Definition: ctr.cpp:197
Botan::xor_buf
void xor_buf(uint8_t out[], const uint8_t in[], size_t length)
Definition: mem_ops.h:232
Botan::CTR_BE::clone
CTR_BE * clone() const override
Definition: ctr.cpp:63
Botan::CTR_BE::clear
void clear() override
Definition: ctr.cpp:39
Botan::is_power_of_2
constexpr bool is_power_of_2(T arg)
Definition: bit_ops.h:43
Botan::copy_mem
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:132
Botan
Definition: alg_id.cpp:13
BOTAN_ARG_CHECK
#define BOTAN_ARG_CHECK(expr, msg)
Definition: assert.h:37
Botan::CTR_BE::key_spec
Key_Length_Specification key_spec() const override
Definition: ctr.cpp:58
Botan::CTR_BE::CTR_BE
CTR_BE(BlockCipher *cipher)
Definition: ctr.cpp:15
Botan::SymmetricAlgorithm::verify_key_set
void verify_key_set(bool cond) const
Definition: sym_algo.h:89
Botan::CTR_BE::set_iv
void set_iv(const uint8_t iv[], size_t iv_len) override
Definition: ctr.cpp:125
Botan::CTR_BE::cipher
void cipher(const uint8_t in[], uint8_t out[], size_t length) override
Definition: ctr.cpp:85
Botan::buffer_insert
size_t buffer_insert(std::vector< T, Alloc > &buf, size_t buf_offset, const T input[], size_t input_length)
Definition: secmem.h:80
m_block_size
size_t m_block_size
Definition: openssl_mode.cpp:47
Botan::CTR_BE::valid_iv_length
bool valid_iv_length(size_t iv_len) const override
Definition: ctr.cpp:53
Botan::BlockCipher
Definition: block_cipher.h:21
Botan::zeroise
void zeroise(std::vector< T, Alloc > &vec)
Definition: secmem.h:160