Botan 2.1.0 Crypto and TLS for C++11

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salsa20.cpp
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1 /*
2 * Salsa20 / XSalsa20
3 * (C) 1999-2010,2014 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7
8 #include <botan/salsa20.h>
9 #include <botan/loadstor.h>
10
11 namespace Botan {
12
13 namespace {
14
15 #define SALSA20_QUARTER_ROUND(x1, x2, x3, x4) \
16 do { \
17 x2 ^= rotate_left(x1 + x4, 7); \
18 x3 ^= rotate_left(x2 + x1, 9); \
19 x4 ^= rotate_left(x3 + x2, 13); \
20 x1 ^= rotate_left(x4 + x3, 18); \
21 } while(0)
22
23 /*
24 * Generate HSalsa20 cipher stream (for XSalsa20 IV setup)
25 */
26 void hsalsa20(uint32_t output[8], const uint32_t input[16])
27 {
28 uint32_t x00 = input[ 0], x01 = input[ 1], x02 = input[ 2], x03 = input[ 3],
29 x04 = input[ 4], x05 = input[ 5], x06 = input[ 6], x07 = input[ 7],
30 x08 = input[ 8], x09 = input[ 9], x10 = input[10], x11 = input[11],
31 x12 = input[12], x13 = input[13], x14 = input[14], x15 = input[15];
32
33 for(size_t i = 0; i != 10; ++i)
34 {
35 SALSA20_QUARTER_ROUND(x00, x04, x08, x12);
36 SALSA20_QUARTER_ROUND(x05, x09, x13, x01);
37 SALSA20_QUARTER_ROUND(x10, x14, x02, x06);
38 SALSA20_QUARTER_ROUND(x15, x03, x07, x11);
39
40 SALSA20_QUARTER_ROUND(x00, x01, x02, x03);
41 SALSA20_QUARTER_ROUND(x05, x06, x07, x04);
42 SALSA20_QUARTER_ROUND(x10, x11, x08, x09);
43 SALSA20_QUARTER_ROUND(x15, x12, x13, x14);
44 }
45
46 output[0] = x00;
47 output[1] = x05;
48 output[2] = x10;
49 output[3] = x15;
50 output[4] = x06;
51 output[5] = x07;
52 output[6] = x08;
53 output[7] = x09;
54 }
55
56 /*
57 * Generate Salsa20 cipher stream
58 */
59 void salsa20(uint8_t output[64], const uint32_t input[16])
60 {
61 uint32_t x00 = input[ 0], x01 = input[ 1], x02 = input[ 2], x03 = input[ 3],
62 x04 = input[ 4], x05 = input[ 5], x06 = input[ 6], x07 = input[ 7],
63 x08 = input[ 8], x09 = input[ 9], x10 = input[10], x11 = input[11],
64 x12 = input[12], x13 = input[13], x14 = input[14], x15 = input[15];
65
66 for(size_t i = 0; i != 10; ++i)
67 {
68 SALSA20_QUARTER_ROUND(x00, x04, x08, x12);
69 SALSA20_QUARTER_ROUND(x05, x09, x13, x01);
70 SALSA20_QUARTER_ROUND(x10, x14, x02, x06);
71 SALSA20_QUARTER_ROUND(x15, x03, x07, x11);
72
73 SALSA20_QUARTER_ROUND(x00, x01, x02, x03);
74 SALSA20_QUARTER_ROUND(x05, x06, x07, x04);
75 SALSA20_QUARTER_ROUND(x10, x11, x08, x09);
76 SALSA20_QUARTER_ROUND(x15, x12, x13, x14);
77 }
78
79 store_le(x00 + input[ 0], output + 4 * 0);
80 store_le(x01 + input[ 1], output + 4 * 1);
81 store_le(x02 + input[ 2], output + 4 * 2);
82 store_le(x03 + input[ 3], output + 4 * 3);
83 store_le(x04 + input[ 4], output + 4 * 4);
84 store_le(x05 + input[ 5], output + 4 * 5);
85 store_le(x06 + input[ 6], output + 4 * 6);
86 store_le(x07 + input[ 7], output + 4 * 7);
87 store_le(x08 + input[ 8], output + 4 * 8);
88 store_le(x09 + input[ 9], output + 4 * 9);
89 store_le(x10 + input[10], output + 4 * 10);
90 store_le(x11 + input[11], output + 4 * 11);
91 store_le(x12 + input[12], output + 4 * 12);
92 store_le(x13 + input[13], output + 4 * 13);
93 store_le(x14 + input[14], output + 4 * 14);
94 store_le(x15 + input[15], output + 4 * 15);
95 }
96
97 }
98
99 #undef SALSA20_QUARTER_ROUND
100
101 /*
102 * Combine cipher stream with message
103 */
104 void Salsa20::cipher(const uint8_t in[], uint8_t out[], size_t length)
105 {
106 while(length >= m_buffer.size() - m_position)
107 {
108 xor_buf(out, in, &m_buffer[m_position], m_buffer.size() - m_position);
109 length -= (m_buffer.size() - m_position);
110 in += (m_buffer.size() - m_position);
111 out += (m_buffer.size() - m_position);
112 salsa20(m_buffer.data(), m_state.data());
113
114 ++m_state[8];
115 m_state[9] += (m_state[8] == 0);
116
117 m_position = 0;
118 }
119
120 xor_buf(out, in, &m_buffer[m_position], length);
121
122 m_position += length;
123 }
124
125 /*
126 * Salsa20 Key Schedule
127 */
128 void Salsa20::key_schedule(const uint8_t key[], size_t length)
129 {
130 static const uint32_t TAU[] =
131 { 0x61707865, 0x3120646e, 0x79622d36, 0x6b206574 };
132
133 static const uint32_t SIGMA[] =
134 { 0x61707865, 0x3320646e, 0x79622d32, 0x6b206574 };
135
136 const uint32_t* CONSTANTS = (length == 16) ? TAU : SIGMA;
137
138 m_state.resize(16);
139 m_buffer.resize(64);
140
141 m_state[0] = CONSTANTS[0];
142 m_state[5] = CONSTANTS[1];
143 m_state[10] = CONSTANTS[2];
144 m_state[15] = CONSTANTS[3];
145
146 m_state[1] = load_le<uint32_t>(key, 0);
147 m_state[2] = load_le<uint32_t>(key, 1);
148 m_state[3] = load_le<uint32_t>(key, 2);
149 m_state[4] = load_le<uint32_t>(key, 3);
150
151 if(length == 32)
152 key += 16;
153
154 m_state[11] = load_le<uint32_t>(key, 0);
155 m_state[12] = load_le<uint32_t>(key, 1);
156 m_state[13] = load_le<uint32_t>(key, 2);
157 m_state[14] = load_le<uint32_t>(key, 3);
158
159 m_position = 0;
160
161 set_iv(nullptr, 0); // all-zero IV
162 }
163
164 /*
165 * Set the Salsa IV
166 */
167 void Salsa20::set_iv(const uint8_t iv[], size_t length)
168 {
169 if(!valid_iv_length(length))
170 throw Invalid_IV_Length(name(), length);
171
172 if(length == 0)
173 {
174 // Salsa20 null IV
175 m_state[6] = 0;
176 m_state[7] = 0;
177 }
178 else if(length == 8)
179 {
180 // Salsa20
181 m_state[6] = load_le<uint32_t>(iv, 0);
182 m_state[7] = load_le<uint32_t>(iv, 1);
183 }
184 else
185 {
186 // XSalsa20
187 m_state[6] = load_le<uint32_t>(iv, 0);
188 m_state[7] = load_le<uint32_t>(iv, 1);
189 m_state[8] = load_le<uint32_t>(iv, 2);
190 m_state[9] = load_le<uint32_t>(iv, 3);
191
192 secure_vector<uint32_t> hsalsa(8);
193 hsalsa20(hsalsa.data(), m_state.data());
194
195 m_state[ 1] = hsalsa[0];
196 m_state[ 2] = hsalsa[1];
197 m_state[ 3] = hsalsa[2];
198 m_state[ 4] = hsalsa[3];
199 m_state[ 6] = load_le<uint32_t>(iv, 4);
200 m_state[ 7] = load_le<uint32_t>(iv, 5);
201 m_state[11] = hsalsa[4];
202 m_state[12] = hsalsa[5];
203 m_state[13] = hsalsa[6];
204 m_state[14] = hsalsa[7];
205 }
206
207 m_state[8] = 0;
208 m_state[9] = 0;
209
210 salsa20(m_buffer.data(), m_state.data());
211 ++m_state[8];
212 m_state[9] += (m_state[8] == 0);
213
214 m_position = 0;
215 }
216
217 /*
218 * Return the name of this type
219 */
220 std::string Salsa20::name() const
221 {
222 return "Salsa20";
223 }
224
225 /*
226 * Clear memory of sensitive data
227 */
228 void Salsa20::clear()
229 {
230 zap(m_state);
231 zap(m_buffer);
232 m_position = 0;
233 }
234
235 void Salsa20::seek(uint64_t)
236 {
237 throw Not_Implemented("Salsa20::seek");
238 }
239 }
Botan::xor_buf
void xor_buf(T out[], const T in[], size_t length)
Definition: mem_ops.h:115
Botan::zap
void zap(std::vector< T, Alloc > &vec)
Definition: secmem.h:221
Botan::Salsa20::name
std::string name() const override
Definition: salsa20.cpp:220
Botan::load_le< uint32_t >
uint32_t load_le< uint32_t >(const uint8_t in[], size_t off)
Definition: loadstor.h:204
Botan::Invalid_IV_Length
Definition: exceptn.h:109
Botan::Salsa20::seek
void seek(uint64_t offset) override
Definition: salsa20.cpp:235
Botan::secure_vector
std::vector< T, secure_allocator< T >> secure_vector
Definition: secmem.h:121
SALSA20_QUARTER_ROUND
#define SALSA20_QUARTER_ROUND(x1, x2, x3, x4)
Definition: salsa20.cpp:15
Botan
Definition: alg_id.cpp:13
Botan::Not_Implemented
Definition: exceptn.h:244
Botan::Salsa20::valid_iv_length
bool valid_iv_length(size_t iv_len) const override
Definition: salsa20.h:25
Botan::Salsa20::clear
void clear() override
Definition: salsa20.cpp:228
Botan::Salsa20::set_iv
void set_iv(const uint8_t iv[], size_t iv_len) override
Definition: salsa20.cpp:167
Botan::store_le
void store_le(uint16_t in, uint8_t out[2])
Definition: loadstor.h:457
Botan::Salsa20::cipher
void cipher(const uint8_t in[], uint8_t out[], size_t length) override
Definition: salsa20.cpp:104