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
|
/*
* GOST 34.10-2001 implemenation
* (C) 2007 Falko Strenzke, FlexSecure GmbH
* Manuel Hartl, FlexSecure GmbH
* (C) 2008-2010 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/internal/pk_utils.h>
#include <botan/gost_3410.h>
#include <botan/der_enc.h>
#include <botan/ber_dec.h>
namespace Botan {
std::vector<byte> GOST_3410_PublicKey::x509_subject_public_key() const
{
// Trust CryptoPro to come up with something obnoxious
const BigInt x = public_point().get_affine_x();
const BigInt y = public_point().get_affine_y();
size_t part_size = std::max(x.bytes(), y.bytes());
std::vector<byte> bits(2*part_size);
x.binary_encode(&bits[part_size - x.bytes()]);
y.binary_encode(&bits[2*part_size - y.bytes()]);
// Keys are stored in little endian format (WTF)
for(size_t i = 0; i != part_size / 2; ++i)
{
std::swap(bits[i], bits[part_size-1-i]);
std::swap(bits[part_size+i], bits[2*part_size-1-i]);
}
return DER_Encoder().encode(bits, OCTET_STRING).get_contents_unlocked();
}
AlgorithmIdentifier GOST_3410_PublicKey::algorithm_identifier() const
{
std::vector<byte> params =
DER_Encoder().start_cons(SEQUENCE)
.encode(OID(domain().get_oid()))
.end_cons()
.get_contents_unlocked();
return AlgorithmIdentifier(get_oid(), params);
}
GOST_3410_PublicKey::GOST_3410_PublicKey(const AlgorithmIdentifier& alg_id,
const secure_vector<byte>& key_bits)
{
OID ecc_param_id;
// Also includes hash and cipher OIDs... brilliant design guys
BER_Decoder(alg_id.parameters).start_cons(SEQUENCE).decode(ecc_param_id);
domain_params = EC_Group(ecc_param_id);
secure_vector<byte> bits;
BER_Decoder(key_bits).decode(bits, OCTET_STRING);
const size_t part_size = bits.size() / 2;
// Keys are stored in little endian format (WTF)
for(size_t i = 0; i != part_size / 2; ++i)
{
std::swap(bits[i], bits[part_size-1-i]);
std::swap(bits[part_size+i], bits[2*part_size-1-i]);
}
BigInt x(bits.data(), part_size);
BigInt y(&bits[part_size], part_size);
public_key = PointGFp(domain().get_curve(), x, y);
BOTAN_ASSERT(public_key.on_the_curve(),
"Loaded GOST 34.10 public key is on the curve");
}
namespace {
BigInt decode_le(const byte msg[], size_t msg_len)
{
secure_vector<byte> msg_le(msg, msg + msg_len);
for(size_t i = 0; i != msg_le.size() / 2; ++i)
std::swap(msg_le[i], msg_le[msg_le.size()-1-i]);
return BigInt(msg_le.data(), msg_le.size());
}
/**
* GOST-34.10 signature operation
*/
class GOST_3410_Signature_Operation : public PK_Ops::Signature_with_EMSA
{
public:
typedef GOST_3410_PrivateKey Key_Type;
GOST_3410_Signature_Operation(const GOST_3410_PrivateKey& gost_3410,
const std::string& emsa) :
PK_Ops::Signature_with_EMSA(emsa),
base_point(gost_3410.domain().get_base_point()),
order(gost_3410.domain().get_order()),
x(gost_3410.private_value()) {}
size_t message_parts() const override { return 2; }
size_t message_part_size() const override { return order.bytes(); }
size_t max_input_bits() const override { return order.bits(); }
secure_vector<byte> raw_sign(const byte msg[], size_t msg_len,
RandomNumberGenerator& rng) override;
private:
const PointGFp& base_point;
const BigInt& order;
const BigInt& x;
};
secure_vector<byte>
GOST_3410_Signature_Operation::raw_sign(const byte msg[], size_t msg_len,
RandomNumberGenerator& rng)
{
BigInt k;
do
k.randomize(rng, order.bits()-1);
while(k >= order);
BigInt e = decode_le(msg, msg_len);
e %= order;
if(e == 0)
e = 1;
PointGFp k_times_P = base_point * k;
BOTAN_ASSERT(k_times_P.on_the_curve(), "GOST 34.10 k*g is on the curve");
BigInt r = k_times_P.get_affine_x() % order;
BigInt s = (r*x + k*e) % order;
if(r == 0 || s == 0)
throw Invalid_State("GOST 34.10: r == 0 || s == 0");
secure_vector<byte> output(2*order.bytes());
s.binary_encode(&output[output.size() / 2 - s.bytes()]);
r.binary_encode(&output[output.size() - r.bytes()]);
return output;
}
/**
* GOST-34.10 verification operation
*/
class GOST_3410_Verification_Operation : public PK_Ops::Verification_with_EMSA
{
public:
typedef GOST_3410_PublicKey Key_Type;
GOST_3410_Verification_Operation(const GOST_3410_PublicKey& gost,
const std::string& emsa) :
PK_Ops::Verification_with_EMSA(emsa),
base_point(gost.domain().get_base_point()),
public_point(gost.public_point()),
order(gost.domain().get_order()) {}
size_t message_parts() const override { return 2; }
size_t message_part_size() const override { return order.bytes(); }
size_t max_input_bits() const override { return order.bits(); }
bool with_recovery() const override { return false; }
bool verify(const byte msg[], size_t msg_len,
const byte sig[], size_t sig_len) override;
private:
const PointGFp& base_point;
const PointGFp& public_point;
const BigInt& order;
};
bool GOST_3410_Verification_Operation::verify(const byte msg[], size_t msg_len,
const byte sig[], size_t sig_len)
{
if(sig_len != order.bytes()*2)
return false;
BigInt e = decode_le(msg, msg_len);
BigInt s(sig, sig_len / 2);
BigInt r(sig + sig_len / 2, sig_len / 2);
if(r <= 0 || r >= order || s <= 0 || s >= order)
return false;
e %= order;
if(e == 0)
e = 1;
BigInt v = inverse_mod(e, order);
BigInt z1 = (s*v) % order;
BigInt z2 = (-r*v) % order;
PointGFp R = multi_exponentiate(base_point, z1,
public_point, z2);
if(R.is_zero())
return false;
return (R.get_affine_x() == r);
}
}
BOTAN_REGISTER_PK_SIGNATURE_OP("GOST-34.10", GOST_3410_Signature_Operation);
BOTAN_REGISTER_PK_VERIFY_OP("GOST-34.10", GOST_3410_Verification_Operation);
}
|
