Pl_AES_PDF.cc
4.49 KB
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
#include <qpdf/Pl_AES_PDF.hh>
#include <qpdf/QUtil.hh>
#include <qpdf/MD5.hh>
#include <cstring>
#include <assert.h>
#include <stdexcept>
#include <qpdf/rijndael.h>
#include <string>
#include <stdlib.h>
Pl_AES_PDF::Pl_AES_PDF(char const* identifier, Pipeline* next,
bool encrypt, unsigned char const key[key_size]) :
Pipeline(identifier, next),
encrypt(encrypt),
cbc_mode(true),
first(true),
offset(0),
nrounds(0)
{
static int const keybits = 128;
assert(key_size == KEYLENGTH(keybits));
assert(sizeof(this->rk) / sizeof(uint32_t) == RKLENGTH(keybits));
std::memcpy(this->key, key, key_size);
std::memset(this->rk, 0, sizeof(this->rk));
std::memset(this->inbuf, 0, this->buf_size);
std::memset(this->outbuf, 0, this->buf_size);
std::memset(this->cbc_block, 0, this->buf_size);
if (encrypt)
{
this->nrounds = rijndaelSetupEncrypt(this->rk, this->key, keybits);
}
else
{
this->nrounds = rijndaelSetupDecrypt(this->rk, this->key, keybits);
}
assert(this->nrounds == NROUNDS(keybits));
}
Pl_AES_PDF::~Pl_AES_PDF()
{
// nothing needed
}
void
Pl_AES_PDF::disableCBC()
{
this->cbc_mode = false;
}
void
Pl_AES_PDF::write(unsigned char* data, int len)
{
unsigned int bytes_left = len;
unsigned char* p = data;
while (bytes_left > 0)
{
if (this->offset == this->buf_size)
{
flush(false);
}
unsigned int available = this->buf_size - this->offset;
int bytes = (bytes_left < available ? bytes_left : available);
bytes_left -= bytes;
std::memcpy(this->inbuf + this->offset, p, bytes);
this->offset += bytes;
p += bytes;
}
}
void
Pl_AES_PDF::finish()
{
if (this->encrypt)
{
if (this->offset == this->buf_size)
{
flush(false);
}
// Pad as described in section 3.5.1 of version 1.7 of the PDF
// specification, including providing an entire block of padding
// if the input was a multiple of 16 bytes.
unsigned char pad = this->buf_size - this->offset;
memset(this->inbuf + this->offset, pad, pad);
this->offset = this->buf_size;
flush(false);
}
else
{
if (this->offset != this->buf_size)
{
throw std::runtime_error(
"aes encrypted stream length was not a multiple of " +
QUtil::int_to_string(this->buf_size) + " bytes (offset = " +
QUtil::int_to_string(this->offset) + ")");
}
flush(true);
}
getNext()->finish();
}
void
Pl_AES_PDF::initializeVector()
{
std::string seed_str;
seed_str += QUtil::int_to_string((int)QUtil::get_current_time());
seed_str += " QPDF aes random";
MD5 m;
m.encodeString(seed_str.c_str());
MD5::Digest digest;
m.digest(digest);
assert(sizeof(digest) >= sizeof(unsigned int));
unsigned int seed;
memcpy((void*)(&seed), digest, sizeof(unsigned int));
srandom(seed);
for (unsigned int i = 0; i < this->buf_size; ++i)
{
this->cbc_block[i] = (unsigned char)(random() & 0xff);
}
}
void
Pl_AES_PDF::flush(bool strip_padding)
{
assert(this->offset == this->buf_size);
if (first)
{
first = false;
if (this->cbc_mode)
{
if (encrypt)
{
// Set cbc_block to a random initialization vector and
// write it to the output stream
initializeVector();
getNext()->write(this->cbc_block, this->buf_size);
}
else
{
// Take the first block of input as the initialization
// vector. There's nothing to write at this time.
memcpy(this->cbc_block, this->inbuf, this->buf_size);
this->offset = 0;
return;
}
}
}
if (this->encrypt)
{
if (this->cbc_mode)
{
for (unsigned int i = 0; i < this->buf_size; ++i)
{
this->inbuf[i] ^= this->cbc_block[i];
}
}
rijndaelEncrypt(this->rk, this->nrounds, this->inbuf, this->outbuf);
if (this->cbc_mode)
{
memcpy(this->cbc_block, this->outbuf, this->buf_size);
}
}
else
{
rijndaelDecrypt(this->rk, this->nrounds, this->inbuf, this->outbuf);
if (this->cbc_mode)
{
for (unsigned int i = 0; i < this->buf_size; ++i)
{
this->outbuf[i] ^= this->cbc_block[i];
}
memcpy(this->cbc_block, this->inbuf, this->buf_size);
}
}
unsigned int bytes = this->buf_size;
if (strip_padding)
{
unsigned char last = this->outbuf[this->buf_size - 1];
if (last <= this->buf_size)
{
bool strip = true;
for (unsigned int i = 1; i <= last; ++i)
{
if (this->outbuf[this->buf_size - i] != last)
{
strip = false;
break;
}
}
if (strip)
{
bytes -= last;
}
}
}
getNext()->write(this->outbuf, bytes);
this->offset = 0;
}