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
|
/*************************************************
* CBC Mode Source File *
* (C) 1999-2007 Jack Lloyd *
*************************************************/
#include <botan/cbc.h>
#include <botan/lookup.h>
#include <botan/xor_buf.h>
#include <algorithm>
namespace Botan {
/*************************************************
* CBC Encryption Constructor *
*************************************************/
CBC_Encryption::CBC_Encryption(const std::string& cipher_name,
const std::string& padding_name) :
BlockCipherMode(cipher_name, "CBC", block_size_of(cipher_name)),
padder(get_bc_pad(padding_name))
{
if(!padder->valid_blocksize(BLOCK_SIZE))
throw Invalid_Block_Size(name(), padder->name());
}
/*************************************************
* CBC Encryption Constructor *
*************************************************/
CBC_Encryption::CBC_Encryption(const std::string& cipher_name,
const std::string& padding_name,
const SymmetricKey& key,
const InitializationVector& iv) :
BlockCipherMode(cipher_name, "CBC", block_size_of(cipher_name)),
padder(get_bc_pad(padding_name))
{
if(!padder->valid_blocksize(BLOCK_SIZE))
throw Invalid_Block_Size(name(), padder->name());
set_key(key);
set_iv(iv);
}
/*************************************************
* Encrypt in CBC mode *
*************************************************/
void CBC_Encryption::write(const byte input[], u32bit length)
{
while(length)
{
u32bit xored = std::min(BLOCK_SIZE - position, length);
xor_buf(state + position, input, xored);
input += xored;
length -= xored;
position += xored;
if(position == BLOCK_SIZE)
{
cipher->encrypt(state);
send(state, BLOCK_SIZE);
position = 0;
}
}
}
/*************************************************
* Finish encrypting in CBC mode *
*************************************************/
void CBC_Encryption::end_msg()
{
SecureVector<byte> padding(BLOCK_SIZE);
padder->pad(padding, padding.size(), position);
write(padding, padder->pad_bytes(BLOCK_SIZE, position));
if(position != 0)
throw Exception(name() + ": Did not pad to full blocksize");
}
/*************************************************
* Return a CBC mode name *
*************************************************/
std::string CBC_Encryption::name() const
{
return (cipher->name() + "/" + mode_name + "/" + padder->name());
}
/*************************************************
* CBC Decryption Constructor *
*************************************************/
CBC_Decryption::CBC_Decryption(const std::string& cipher_name,
const std::string& padding_name) :
BlockCipherMode(cipher_name, "CBC", block_size_of(cipher_name)),
padder(get_bc_pad(padding_name))
{
if(!padder->valid_blocksize(BLOCK_SIZE))
throw Invalid_Block_Size(name(), padder->name());
temp.create(BLOCK_SIZE);
}
/*************************************************
* CBC Decryption Constructor *
*************************************************/
CBC_Decryption::CBC_Decryption(const std::string& cipher_name,
const std::string& padding_name,
const SymmetricKey& key,
const InitializationVector& iv) :
BlockCipherMode(cipher_name, "CBC", block_size_of(cipher_name)),
padder(get_bc_pad(padding_name))
{
if(!padder->valid_blocksize(BLOCK_SIZE))
throw Invalid_Block_Size(name(), padder->name());
temp.create(BLOCK_SIZE);
set_key(key);
set_iv(iv);
}
/*************************************************
* Decrypt in CBC mode *
*************************************************/
void CBC_Decryption::write(const byte input[], u32bit length)
{
while(length)
{
if(position == BLOCK_SIZE)
{
cipher->decrypt(buffer, temp);
xor_buf(temp, state, BLOCK_SIZE);
send(temp, BLOCK_SIZE);
state = buffer;
position = 0;
}
u32bit added = std::min(BLOCK_SIZE - position, length);
buffer.copy(position, input, added);
input += added;
length -= added;
position += added;
}
}
/*************************************************
* Finish decrypting in CBC mode *
*************************************************/
void CBC_Decryption::end_msg()
{
if(position != BLOCK_SIZE)
throw Decoding_Error(name());
cipher->decrypt(buffer, temp);
xor_buf(temp, state, BLOCK_SIZE);
send(temp, padder->unpad(temp, BLOCK_SIZE));
state = buffer;
position = 0;
}
/*************************************************
* Return a CBC mode name *
*************************************************/
std::string CBC_Decryption::name() const
{
return (cipher->name() + "/" + mode_name + "/" + padder->name());
}
}
|
