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
|
/*
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
MA 02110-1301 USA.
*/
/* based on Wei Dai's rsa.cpp from CryptoPP */
#include "runtime.hpp"
#include "rsa.hpp"
#include "asn.hpp"
#include "modarith.hpp"
namespace TaoCrypt {
Integer RSA_PublicKey::ApplyFunction(const Integer& x) const
{
return a_exp_b_mod_c(x, e_, n_);
}
RSA_PublicKey::RSA_PublicKey(Source& source)
{
Initialize(source);
}
void RSA_PublicKey::Initialize(Source& source)
{
RSA_Public_Decoder decoder(source);
decoder.Decode(*this);
}
Integer RSA_PrivateKey::CalculateInverse(RandomNumberGenerator& rng,
const Integer& x) const
{
ModularArithmetic modn(n_);
Integer r(rng, Integer::One(), n_ - Integer::One());
Integer re = modn.Exponentiate(r, e_);
re = modn.Multiply(re, x); // blind
// here we follow the notation of PKCS #1 and let u=q inverse mod p
// but in ModRoot, u=p inverse mod q, so we reverse the order of p and q
Integer y = ModularRoot(re, dq_, dp_, q_, p_, u_);
y = modn.Divide(y, r); // unblind
return y;
}
RSA_PrivateKey::RSA_PrivateKey(Source& source)
{
Initialize(source);
}
void RSA_PrivateKey::Initialize(Source& source)
{
RSA_Private_Decoder decoder(source);
decoder.Decode(*this);
}
void RSA_BlockType2::Pad(const byte *input, word32 inputLen, byte *pkcsBlock,
word32 pkcsBlockLen, RandomNumberGenerator& rng) const
{
// convert from bit length to byte length
if (pkcsBlockLen % 8 != 0)
{
pkcsBlock[0] = 0;
pkcsBlock++;
}
pkcsBlockLen /= 8;
pkcsBlock[0] = 2; // block type 2
// pad with non-zero random bytes
word32 padLen = pkcsBlockLen - inputLen - 1;
rng.GenerateBlock(&pkcsBlock[1], padLen);
for (word32 i = 1; i < padLen; i++)
if (pkcsBlock[i] == 0) pkcsBlock[i] = 0x01;
pkcsBlock[pkcsBlockLen-inputLen-1] = 0; // separator
memcpy(pkcsBlock+pkcsBlockLen-inputLen, input, inputLen);
}
word32 RSA_BlockType2::UnPad(const byte *pkcsBlock, unsigned int pkcsBlockLen,
byte *output) const
{
bool invalid = false;
unsigned int maxOutputLen = SaturatingSubtract(pkcsBlockLen / 8, 10U);
// convert from bit length to byte length
if (pkcsBlockLen % 8 != 0)
{
invalid = (pkcsBlock[0] != 0) || invalid;
pkcsBlock++;
}
pkcsBlockLen /= 8;
// Require block type 2.
invalid = (pkcsBlock[0] != 2) || invalid;
// skip past the padding until we find the separator
unsigned i=1;
while (i<pkcsBlockLen && pkcsBlock[i++]) { // null body
}
if (!(i==pkcsBlockLen || pkcsBlock[i-1]==0))
return 0;
unsigned int outputLen = pkcsBlockLen - i;
invalid = (outputLen > maxOutputLen) || invalid;
if (invalid)
return 0;
memcpy (output, pkcsBlock+i, outputLen);
return outputLen;
}
void RSA_BlockType1::Pad(const byte* input, word32 inputLen, byte* pkcsBlock,
word32 pkcsBlockLen, RandomNumberGenerator&) const
{
// convert from bit length to byte length
if (pkcsBlockLen % 8 != 0)
{
pkcsBlock[0] = 0;
pkcsBlock++;
}
pkcsBlockLen /= 8;
pkcsBlock[0] = 1; // block type 1 for SSL
// pad with 0xff bytes
memset(&pkcsBlock[1], 0xFF, pkcsBlockLen - inputLen - 2);
pkcsBlock[pkcsBlockLen-inputLen-1] = 0; // separator
memcpy(pkcsBlock+pkcsBlockLen-inputLen, input, inputLen);
}
word32 RSA_BlockType1::UnPad(const byte* pkcsBlock, word32 pkcsBlockLen,
byte* output) const
{
bool invalid = false;
unsigned int maxOutputLen = SaturatingSubtract(pkcsBlockLen / 8, 10U);
// convert from bit length to byte length
if (pkcsBlockLen % 8 != 0)
{
invalid = (pkcsBlock[0] != 0) || invalid;
pkcsBlock++;
}
pkcsBlockLen /= 8;
// Require block type 1 for SSL.
invalid = (pkcsBlock[0] != 1) || invalid;
// skip past the padding until we find the separator
unsigned i=1;
while (i<pkcsBlockLen && pkcsBlock[i++] == 0xFF) { // null body
}
if (!(i==pkcsBlockLen || pkcsBlock[i-1]==0))
return 0;
unsigned int outputLen = pkcsBlockLen - i;
invalid = (outputLen > maxOutputLen) || invalid;
if (invalid)
return 0;
memcpy(output, pkcsBlock+i, outputLen);
return outputLen;
}
word32 SSL_Decrypt(const RSA_PublicKey& key, const byte* sig, byte* plain)
{
PK_Lengths lengths(key.GetModulus());
ByteBlock paddedBlock(BitsToBytes(lengths.PaddedBlockBitLength()));
Integer x = key.ApplyFunction(Integer(sig,
lengths.FixedCiphertextLength()));
if (x.ByteCount() > paddedBlock.size())
x = Integer::Zero();
x.Encode(paddedBlock.get_buffer(), paddedBlock.size());
return RSA_BlockType1().UnPad(paddedBlock.get_buffer(),
lengths.PaddedBlockBitLength(), plain);
}
} // namespace
|
