Botan: src/stream/salsa20/salsa20.cpp Source File

Botan 1.10.16

salsa20.cpp
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1 /*
2 * Salsa20 / XSalsa20
3 * (C) 1999-2010 Jack Lloyd
4 *
5 * Distributed under the terms of the Botan license
6 */
7
8 #include <botan/salsa20.h>
9 #include <botan/loadstor.h>
10 #include <botan/rotate.h>
11 #include <botan/internal/xor_buf.h>
12
13 namespace Botan {
14
15 namespace {
16
17 #define SALSA20_QUARTER_ROUND(x1, x2, x3, x4) \
18 do { \
19 x2 ^= rotate_left(x1 + x4, 7); \
20 x3 ^= rotate_left(x2 + x1, 9); \
21 x4 ^= rotate_left(x3 + x2, 13); \
22 x1 ^= rotate_left(x4 + x3, 18); \
23 } while(0)
24
25 /*
26 * Generate HSalsa20 cipher stream (for XSalsa20 IV setup)
27 */
28 void hsalsa20(u32bit output[8], const u32bit input[16])
29 {
30 u32bit x00 = input[ 0], x01 = input[ 1], x02 = input[ 2], x03 = input[ 3],
31 x04 = input[ 4], x05 = input[ 5], x06 = input[ 6], x07 = input[ 7],
32 x08 = input[ 8], x09 = input[ 9], x10 = input[10], x11 = input[11],
33 x12 = input[12], x13 = input[13], x14 = input[14], x15 = input[15];
34
35 for(size_t i = 0; i != 10; ++i)
36 {
37 SALSA20_QUARTER_ROUND(x00, x04, x08, x12);
38 SALSA20_QUARTER_ROUND(x05, x09, x13, x01);
39 SALSA20_QUARTER_ROUND(x10, x14, x02, x06);
40 SALSA20_QUARTER_ROUND(x15, x03, x07, x11);
41
42 SALSA20_QUARTER_ROUND(x00, x01, x02, x03);
43 SALSA20_QUARTER_ROUND(x05, x06, x07, x04);
44 SALSA20_QUARTER_ROUND(x10, x11, x08, x09);
45 SALSA20_QUARTER_ROUND(x15, x12, x13, x14);
46 }
47
48 output[0] = x00;
49 output[1] = x05;
50 output[2] = x10;
51 output[3] = x15;
52 output[4] = x06;
53 output[5] = x07;
54 output[6] = x08;
55 output[7] = x09;
56 }
57
58 /*
59 * Generate Salsa20 cipher stream
60 */
61 void salsa20(byte output[64], const u32bit input[16])
62 {
63 u32bit x00 = input[ 0], x01 = input[ 1], x02 = input[ 2], x03 = input[ 3],
64 x04 = input[ 4], x05 = input[ 5], x06 = input[ 6], x07 = input[ 7],
65 x08 = input[ 8], x09 = input[ 9], x10 = input[10], x11 = input[11],
66 x12 = input[12], x13 = input[13], x14 = input[14], x15 = input[15];
67
68 for(size_t i = 0; i != 10; ++i)
69 {
70 SALSA20_QUARTER_ROUND(x00, x04, x08, x12);
71 SALSA20_QUARTER_ROUND(x05, x09, x13, x01);
72 SALSA20_QUARTER_ROUND(x10, x14, x02, x06);
73 SALSA20_QUARTER_ROUND(x15, x03, x07, x11);
74
75 SALSA20_QUARTER_ROUND(x00, x01, x02, x03);
76 SALSA20_QUARTER_ROUND(x05, x06, x07, x04);
77 SALSA20_QUARTER_ROUND(x10, x11, x08, x09);
78 SALSA20_QUARTER_ROUND(x15, x12, x13, x14);
79 }
80
81 store_le(x00 + input[ 0], output + 4 * 0);
82 store_le(x01 + input[ 1], output + 4 * 1);
83 store_le(x02 + input[ 2], output + 4 * 2);
84 store_le(x03 + input[ 3], output + 4 * 3);
85 store_le(x04 + input[ 4], output + 4 * 4);
86 store_le(x05 + input[ 5], output + 4 * 5);
87 store_le(x06 + input[ 6], output + 4 * 6);
88 store_le(x07 + input[ 7], output + 4 * 7);
89 store_le(x08 + input[ 8], output + 4 * 8);
90 store_le(x09 + input[ 9], output + 4 * 9);
91 store_le(x10 + input[10], output + 4 * 10);
92 store_le(x11 + input[11], output + 4 * 11);
93 store_le(x12 + input[12], output + 4 * 12);
94 store_le(x13 + input[13], output + 4 * 13);
95 store_le(x14 + input[14], output + 4 * 14);
96 store_le(x15 + input[15], output + 4 * 15);
97 }
98
99 }
100
101 /*
102 * Combine cipher stream with message
103 */
104 void Salsa20::cipher(const byte in[], byte out[], size_t length)
105 {
106 while(length >= buffer.size() - position)
107 {
108 xor_buf(out, in, &buffer[position], buffer.size() - position);
109 length -= (buffer.size() - position);
110 in += (buffer.size() - position);
111 out += (buffer.size() - position);
112 salsa20(&buffer[0], &state[0]);
113
114 ++state[8];
115 if(!state[8]) // if overflow in state[8]
116 ++state[9]; // carry to state[9]
117
118 position = 0;
119 }
120
121 xor_buf(out, in, &buffer[position], length);
122
123 position += length;
124 }
125
126 /*
127 * Salsa20 Key Schedule
128 */
129 void Salsa20::key_schedule(const byte key[], size_t length)
130 {
131 static const u32bit TAU[] =
132 { 0x61707865, 0x3120646e, 0x79622d36, 0x6b206574 };
133
134 static const u32bit SIGMA[] =
135 { 0x61707865, 0x3320646e, 0x79622d32, 0x6b206574 };
136
137 clear();
138
139 if(length == 16)
140 {
141 state[0] = TAU[0];
142 state[1] = load_le<u32bit>(key, 0);
143 state[2] = load_le<u32bit>(key, 1);
144 state[3] = load_le<u32bit>(key, 2);
145 state[4] = load_le<u32bit>(key, 3);
146 state[5] = TAU[1];
147 state[10] = TAU[2];
148 state[11] = load_le<u32bit>(key, 0);
149 state[12] = load_le<u32bit>(key, 1);
150 state[13] = load_le<u32bit>(key, 2);
151 state[14] = load_le<u32bit>(key, 3);
152 state[15] = TAU[3];
153 }
154 else if(length == 32)
155 {
156 state[0] = SIGMA[0];
157 state[1] = load_le<u32bit>(key, 0);
158 state[2] = load_le<u32bit>(key, 1);
159 state[3] = load_le<u32bit>(key, 2);
160 state[4] = load_le<u32bit>(key, 3);
161 state[5] = SIGMA[1];
162 state[10] = SIGMA[2];
163 state[11] = load_le<u32bit>(key, 4);
164 state[12] = load_le<u32bit>(key, 5);
165 state[13] = load_le<u32bit>(key, 6);
166 state[14] = load_le<u32bit>(key, 7);
167 state[15] = SIGMA[3];
168 }
169
170 const byte ZERO[8] = { 0 };
171 set_iv(ZERO, sizeof(ZERO));
172 }
173
174 /*
175 * Return the name of this type
176 */
177 void Salsa20::set_iv(const byte iv[], size_t length)
178 {
179 if(!valid_iv_length(length))
180 throw Invalid_IV_Length(name(), length);
181
182 if(length == 8)
183 {
184 // Salsa20
185 state[6] = load_le<u32bit>(iv, 0);
186 state[7] = load_le<u32bit>(iv, 1);
187 }
188 else
189 {
190 // XSalsa20
191 state[6] = load_le<u32bit>(iv, 0);
192 state[7] = load_le<u32bit>(iv, 1);
193 state[8] = load_le<u32bit>(iv, 2);
194 state[9] = load_le<u32bit>(iv, 3);
195
196 SecureVector<u32bit> hsalsa(8);
197 hsalsa20(&hsalsa[0], &state[0]);
198
199 state[ 1] = hsalsa[0];
200 state[ 2] = hsalsa[1];
201 state[ 3] = hsalsa[2];
202 state[ 4] = hsalsa[3];
203 state[ 6] = load_le<u32bit>(iv, 4);
204 state[ 7] = load_le<u32bit>(iv, 5);
205 state[11] = hsalsa[4];
206 state[12] = hsalsa[5];
207 state[13] = hsalsa[6];
208 state[14] = hsalsa[7];
209 }
210
211 state[8] = 0;
212 state[9] = 0;
213
214 salsa20(&buffer[0], &state[0]);
215 ++state[8];
216 if(!state[8]) // if overflow in state[8]
217 ++state[9]; // carry to state[9]
218
219 position = 0;
220 }
221
222 /*
223 * Return the name of this type
224 */
225 std::string Salsa20::name() const
226 {
227 return "Salsa20";
228 }
229
230 /*
231 * Clear memory of sensitive data
232 */
233 void Salsa20::clear()
234 {
235 zeroise(state);
236 zeroise(buffer);
237 position = 0;
238 }
239
240 }
Botan::Salsa20::set_iv
void set_iv(const byte iv[], size_t iv_len)
Definition: salsa20.cpp:177
Botan::store_le
void store_le(u16bit in, byte out[2])
Definition: loadstor.h:427
Botan::Invalid_IV_Length
Definition: exceptn.h:78
Botan::byte
unsigned char byte
Definition: types.h:22
Botan::load_le< u32bit >
u32bit load_le< u32bit >(const byte in[], size_t off)
Definition: loadstor.h:183
Botan::Salsa20::valid_iv_length
bool valid_iv_length(size_t iv_len) const
Definition: salsa20.h:25
SALSA20_QUARTER_ROUND
#define SALSA20_QUARTER_ROUND(x1, x2, x3, x4)
Definition: salsa20.cpp:17
Botan::Salsa20::name
std::string name() const
Definition: salsa20.cpp:225
Botan
Definition: algo_base.h:14
Botan::Salsa20::cipher
void cipher(const byte in[], byte out[], size_t length)
Definition: salsa20.cpp:104
Botan::MemoryRegion::size
size_t size() const
Definition: secmem.h:29
Botan::SecureVector< u32bit >
Botan::Salsa20::clear
void clear()
Definition: salsa20.cpp:233
Botan::xor_buf
void xor_buf(byte out[], const byte in[], size_t length)
Definition: xor_buf.h:21
Botan::zeroise
void zeroise(MemoryRegion< T > &vec)
Definition: secmem.h:415
Botan::u32bit
unsigned int u32bit
Definition: types.h:32