1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
|
/*
* GCM GHASH
* (C) 2013,2015,2017 Jack Lloyd
* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/ghash.h>
#include <botan/internal/ct_utils.h>
#include <botan/loadstor.h>
#include <botan/cpuid.h>
#include <botan/exceptn.h>
namespace Botan {
std::string GHASH::provider() const
{
#if defined(BOTAN_HAS_GHASH_CLMUL_CPU)
if(CPUID::has_carryless_multiply())
return "clmul";
#endif
#if defined(BOTAN_HAS_GHASH_CLMUL_VPERM)
if(CPUID::has_vperm())
return "vperm";
#endif
return "base";
}
void GHASH::ghash_multiply(secure_vector<uint8_t>& x,
const uint8_t input[],
size_t blocks)
{
#if defined(BOTAN_HAS_GHASH_CLMUL_CPU)
if(CPUID::has_carryless_multiply())
{
return ghash_multiply_cpu(x.data(), m_H_pow.data(), input, blocks);
}
#endif
#if defined(BOTAN_HAS_GHASH_CLMUL_VPERM)
if(CPUID::has_vperm())
{
return ghash_multiply_vperm(x.data(), m_HM.data(), input, blocks);
}
#endif
CT::poison(x.data(), x.size());
const uint64_t ALL_BITS = 0xFFFFFFFFFFFFFFFF;
uint64_t X[2] = {
load_be<uint64_t>(x.data(), 0),
load_be<uint64_t>(x.data(), 1)
};
for(size_t b = 0; b != blocks; ++b)
{
X[0] ^= load_be<uint64_t>(input, 2*b);
X[1] ^= load_be<uint64_t>(input, 2*b+1);
uint64_t Z[2] = { 0, 0 };
for(size_t i = 0; i != 64; ++i)
{
const uint64_t X0MASK = (ALL_BITS + (X[0] >> 63)) ^ ALL_BITS;
const uint64_t X1MASK = (ALL_BITS + (X[1] >> 63)) ^ ALL_BITS;
X[0] <<= 1;
X[1] <<= 1;
Z[0] ^= m_HM[4*i ] & X0MASK;
Z[1] ^= m_HM[4*i+1] & X0MASK;
Z[0] ^= m_HM[4*i+2] & X1MASK;
Z[1] ^= m_HM[4*i+3] & X1MASK;
}
X[0] = Z[0];
X[1] = Z[1];
}
store_be<uint64_t>(x.data(), X[0], X[1]);
CT::unpoison(x.data(), x.size());
}
void GHASH::ghash_update(secure_vector<uint8_t>& ghash,
const uint8_t input[], size_t length)
{
verify_key_set(!m_HM.empty());
/*
This assumes if less than block size input then we're just on the
final block and should pad with zeros
*/
const size_t full_blocks = length / GCM_BS;
const size_t final_bytes = length - (full_blocks * GCM_BS);
if(full_blocks > 0)
{
ghash_multiply(ghash, input, full_blocks);
}
if(final_bytes)
{
uint8_t last_block[GCM_BS] = { 0 };
copy_mem(last_block, input + full_blocks * GCM_BS, final_bytes);
ghash_multiply(ghash, last_block, 1);
secure_scrub_memory(last_block, final_bytes);
}
}
void GHASH::key_schedule(const uint8_t key[], size_t length)
{
m_H.assign(key, key+length);
m_H_ad.resize(GCM_BS);
m_ad_len = 0;
m_text_len = 0;
uint64_t H0 = load_be<uint64_t>(m_H.data(), 0);
uint64_t H1 = load_be<uint64_t>(m_H.data(), 1);
const uint64_t R = 0xE100000000000000;
m_HM.resize(256);
// precompute the multiples of H
for(size_t i = 0; i != 2; ++i)
{
for(size_t j = 0; j != 64; ++j)
{
/*
we interleave H^1, H^65, H^2, H^66, H3, H67, H4, H68
to make indexing nicer in the multiplication code
*/
m_HM[4*j+2*i] = H0;
m_HM[4*j+2*i+1] = H1;
// GCM's bit ops are reversed so we carry out of the bottom
const uint64_t carry = R * (H1 & 1);
H1 = (H1 >> 1) | (H0 << 63);
H0 = (H0 >> 1) ^ carry;
}
}
#if defined(BOTAN_HAS_GHASH_CLMUL_CPU)
if(CPUID::has_carryless_multiply())
{
m_H_pow.resize(8);
ghash_precompute_cpu(m_H.data(), m_H_pow.data());
}
#endif
}
void GHASH::start(const uint8_t nonce[], size_t len)
{
BOTAN_ARG_CHECK(len == 16, "GHASH requires a 128-bit nonce");
m_nonce.assign(nonce, nonce + len);
m_ghash = m_H_ad;
}
void GHASH::set_associated_data(const uint8_t input[], size_t length)
{
if(m_ghash.empty() == false)
throw Invalid_State("Too late to set AD in GHASH");
zeroise(m_H_ad);
ghash_update(m_H_ad, input, length);
m_ad_len = length;
}
void GHASH::update_associated_data(const uint8_t ad[], size_t length)
{
verify_key_set(m_ghash.size() == GCM_BS);
m_ad_len += length;
ghash_update(m_ghash, ad, length);
}
void GHASH::update(const uint8_t input[], size_t length)
{
verify_key_set(m_ghash.size() == GCM_BS);
m_text_len += length;
ghash_update(m_ghash, input, length);
}
void GHASH::add_final_block(secure_vector<uint8_t>& hash,
size_t ad_len, size_t text_len)
{
/*
* stack buffer is fine here since the text len is public
* and the length of the AD is probably not sensitive either.
*/
uint8_t final_block[GCM_BS];
store_be<uint64_t>(final_block, 8*ad_len, 8*text_len);
ghash_update(hash, final_block, GCM_BS);
}
void GHASH::final(uint8_t mac[], size_t mac_len)
{
BOTAN_ARG_CHECK(mac_len > 0 && mac_len <= 16, "GHASH output length");
add_final_block(m_ghash, m_ad_len, m_text_len);
for(size_t i = 0; i != mac_len; ++i)
mac[i] = m_ghash[i] ^ m_nonce[i];
m_ghash.clear();
m_text_len = 0;
}
void GHASH::nonce_hash(secure_vector<uint8_t>& y0, const uint8_t nonce[], size_t nonce_len)
{
BOTAN_ASSERT(m_ghash.size() == 0, "nonce_hash called during wrong time");
ghash_update(y0, nonce, nonce_len);
add_final_block(y0, 0, nonce_len);
}
void GHASH::clear()
{
zap(m_H);
zap(m_HM);
reset();
}
void GHASH::reset()
{
zeroise(m_H_ad);
m_ghash.clear();
m_nonce.clear();
m_text_len = m_ad_len = 0;
}
}
|
