aboutsummaryrefslogtreecommitdiffstats
path: root/src/pubkey/nr/nr.cpp
blob: 244a397ee2c68fd5ee1080416bba1ff7f4caeb66 (plain)
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
/*
* Nyberg-Rueppel
* (C) 1999-2010 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/

#include <botan/nr.h>
#include <botan/numthry.h>
#include <botan/keypair.h>

namespace Botan {

NR_PublicKey::NR_PublicKey(const AlgorithmIdentifier& alg_id,
                           const MemoryRegion<byte>& key_bits) :
   DL_Scheme_PublicKey(alg_id, key_bits, DL_Group::ANSI_X9_57)
   {
   }

/*
* NR_PublicKey Constructor
*/
NR_PublicKey::NR_PublicKey(const DL_Group& grp, const BigInt& y1)
   {
   group = grp;
   y = y1;
   }

/*
* Create a NR private key
*/
NR_PrivateKey::NR_PrivateKey(RandomNumberGenerator& rng,
                             const DL_Group& grp,
                             const BigInt& x_arg)
   {
   group = grp;
   x = x_arg;

   if(x == 0)
      x = BigInt::random_integer(rng, 2, group_q() - 1);

   y = power_mod(group_g(), x, group_p());

   if(x_arg == 0)
      gen_check(rng);
   else
      load_check(rng);
   }

NR_PrivateKey::NR_PrivateKey(const AlgorithmIdentifier& alg_id,
                             const MemoryRegion<byte>& key_bits,
                             RandomNumberGenerator& rng) :
   DL_Scheme_PrivateKey(alg_id, key_bits, DL_Group::ANSI_X9_57)
   {
   y = power_mod(group_g(), x, group_p());

   load_check(rng);
   }

/*
* Check Private Nyberg-Rueppel Parameters
*/
bool NR_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const
   {
   if(!DL_Scheme_PrivateKey::check_key(rng, strong) || x >= group_q())
      return false;

   if(!strong)
      return true;

   return KeyPair::signature_consistency_check(rng, *this, "EMSA1(SHA-1)");
   }

NR_Signature_Operation::NR_Signature_Operation(const NR_PrivateKey& nr) :
   q(nr.group_q()),
   x(nr.get_x()),
   powermod_g_p(nr.group_g(), nr.group_p()),
   mod_q(nr.group_q())
   {
   }

SecureVector<byte>
NR_Signature_Operation::sign(const byte msg[], u32bit msg_len,
                             RandomNumberGenerator& rng)
   {
   rng.add_entropy(msg, msg_len);

   BigInt f(msg, msg_len);

   if(f >= q)
      throw Invalid_Argument("NR_Signature_Operation: Input is out of range");

   BigInt c, d;

   while(c == 0)
      {
      BigInt k;
      do
         k.randomize(rng, q.bits());
      while(k >= q);

      c = mod_q.reduce(powermod_g_p(k) + f);
      d = mod_q.reduce(k - x * c);
      }

   SecureVector<byte> output(2*q.bytes());
   c.binary_encode(&output[output.size() / 2 - c.bytes()]);
   d.binary_encode(&output[output.size() - d.bytes()]);
   return output;
   }

NR_Verification_Operation::NR_Verification_Operation(const NR_PublicKey& nr) :
   q(nr.group_q()), y(nr.get_y())
   {
   powermod_g_p = Fixed_Base_Power_Mod(nr.group_g(), nr.group_p());
   powermod_y_p = Fixed_Base_Power_Mod(y, nr.group_p());
   mod_p = Modular_Reducer(nr.group_p());
   mod_q = Modular_Reducer(nr.group_q());
   }

SecureVector<byte>
NR_Verification_Operation::verify_mr(const byte msg[], u32bit msg_len)
   {
   const BigInt& q = mod_q.get_modulus();

   if(msg_len != 2*q.bytes())
      return false;

   BigInt c(msg, q.bytes());
   BigInt d(msg + q.bytes(), q.bytes());

   if(c.is_zero() || c >= q || d >= q)
      throw Invalid_Argument("NR verification: Invalid signature");

   BigInt i = mod_p.multiply(powermod_g_p(d), powermod_y_p(c));
   return BigInt::encode(mod_q.reduce(c - i));
   }

}