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
|
/*
* (C) 2015,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef ECC_HELPERS_H_
#define ECC_HELPERS_H_
#include "fuzzers.h"
#include <botan/ec_group.h>
#include <botan/reducer.h>
#include <botan/numthry.h>
namespace {
inline std::ostream& operator<<(std::ostream& o, const Botan::PointGFp& point)
{
o << point.get_affine_x() << "," << point.get_affine_y();
return o;
}
Botan::BigInt decompress_point(bool yMod2,
const Botan::BigInt& x,
const Botan::BigInt& curve_p,
const Botan::BigInt& curve_a,
const Botan::BigInt& curve_b)
{
Botan::BigInt xpow3 = x * x * x;
Botan::BigInt g = curve_a * x;
g += xpow3;
g += curve_b;
g = g % curve_p;
Botan::BigInt z = ressol(g, curve_p);
if(z < 0)
throw Botan::Exception("Could not perform square root");
if(z.get_bit(0) != yMod2)
z = curve_p - z;
return z;
}
void check_ecc_math(const Botan::EC_Group& group,
const uint8_t in[], size_t len)
{
// These depend only on the group, which is also static
static const Botan::PointGFp base_point = group.get_base_point();
// This is shared across runs to reduce overhead
static std::vector<Botan::BigInt> ws(Botan::PointGFp::WORKSPACE_SIZE);
const size_t hlen = len / 2;
const Botan::BigInt a = Botan::BigInt::decode(in, hlen);
const Botan::BigInt b = Botan::BigInt::decode(in + hlen, len - hlen);
const Botan::BigInt c = a + b;
const Botan::PointGFp P1 = base_point * a;
const Botan::PointGFp Q1 = base_point * b;
const Botan::PointGFp R1 = base_point * c;
const Botan::PointGFp S1 = P1 + Q1;
const Botan::PointGFp T1 = Q1 + P1;
FUZZER_ASSERT_EQUAL(S1, R1);
FUZZER_ASSERT_EQUAL(T1, R1);
const Botan::PointGFp P2 = group.blinded_base_point_multiply(a, fuzzer_rng(), ws);
const Botan::PointGFp Q2 = group.blinded_base_point_multiply(b, fuzzer_rng(), ws);
const Botan::PointGFp R2 = group.blinded_base_point_multiply(c, fuzzer_rng(), ws);
const Botan::PointGFp S2 = P2 + Q2;
const Botan::PointGFp T2 = Q2 + P2;
FUZZER_ASSERT_EQUAL(S2, R2);
FUZZER_ASSERT_EQUAL(T2, R2);
const Botan::PointGFp P3 = group.blinded_var_point_multiply(base_point, a, fuzzer_rng(), ws);
const Botan::PointGFp Q3 = group.blinded_var_point_multiply(base_point, b, fuzzer_rng(), ws);
const Botan::PointGFp R3 = group.blinded_var_point_multiply(base_point, c, fuzzer_rng(), ws);
const Botan::PointGFp S3 = P3 + Q3;
const Botan::PointGFp T3 = Q3 + P3;
FUZZER_ASSERT_EQUAL(S3, R3);
FUZZER_ASSERT_EQUAL(T3, R3);
FUZZER_ASSERT_EQUAL(S1, S2);
FUZZER_ASSERT_EQUAL(S1, S3);
try
{
const auto yp = decompress_point(true, a, group.get_p(), group.get_a(), group.get_b());
const auto pt_p = group.blinded_var_point_multiply(group.point(a, yp), b, fuzzer_rng(), ws);
const auto yn = -yp;
const auto pt_n = group.blinded_var_point_multiply(group.point(a, yn), b, fuzzer_rng(), ws);
FUZZER_ASSERT_EQUAL(pt_p, -pt_n);
}
catch(...) {}
}
}
#endif
|
