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
|
/*************************************************
* DSA Operations Source File *
* (C) 1999-2007 Jack Lloyd *
*************************************************/
#include <botan/dsa_op.h>
#include <botan/eng_def.h>
namespace Botan {
/*************************************************
* Default_DSA_Op Constructor *
*************************************************/
Default_DSA_Op::Default_DSA_Op(const DL_Group& grp, const BigInt& y1,
const BigInt& x1) : x(x1), y(y1), group(grp)
{
powermod_g_p = Fixed_Base_Power_Mod(group.get_g(), group.get_p());
powermod_y_p = Fixed_Base_Power_Mod(y, group.get_p());
mod_p = Modular_Reducer(group.get_p());
mod_q = Modular_Reducer(group.get_q());
}
/*************************************************
* Default DSA Verify Operation *
*************************************************/
bool Default_DSA_Op::verify(const byte msg[], u32bit msg_len,
const byte sig[], u32bit sig_len) const
{
const BigInt& q = group.get_q();
if(sig_len != 2*q.bytes() || msg_len > q.bytes())
return false;
BigInt r(sig, q.bytes());
BigInt s(sig + q.bytes(), q.bytes());
BigInt i(msg, msg_len);
if(r <= 0 || r >= q || s <= 0 || s >= q)
return false;
s = inverse_mod(s, q);
s = mod_p.multiply(powermod_g_p(mod_q.multiply(s, i)),
powermod_y_p(mod_q.multiply(s, r)));
return (mod_q.reduce(s) == r);
}
/*************************************************
* Default DSA Sign Operation *
*************************************************/
SecureVector<byte> Default_DSA_Op::sign(const byte in[], u32bit length,
const BigInt& k) const
{
if(x == 0)
throw Internal_Error("Default_DSA_Op::sign: No private key");
const BigInt& q = group.get_q();
BigInt i(in, length);
BigInt r = mod_q.reduce(powermod_g_p(k));
BigInt s = mod_q.multiply(inverse_mod(k, q), mul_add(x, r, i));
if(r.is_zero() || s.is_zero())
throw Internal_Error("Default_DSA_Op::sign: r or s was zero");
SecureVector<byte> output(2*q.bytes());
r.binary_encode(output + (output.size() / 2 - r.bytes()));
s.binary_encode(output + (output.size() - s.bytes()));
return output;
}
/*************************************************
* Acquire a DSA op *
*************************************************/
DSA_Operation* Default_Engine::dsa_op(const DL_Group& group, const BigInt& y,
const BigInt& x) const
{
return new Default_DSA_Op(group, y, x);
}
}
|
