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
|
/*************************************************
* CTS Mode Source File *
* (C) 1999-2005 The Botan Project *
*************************************************/
#include <botan/cts.h>
#include <botan/lookup.h>
#include <botan/bit_ops.h>
namespace Botan {
/*************************************************
* CTS Encryption Constructor *
*************************************************/
CTS_Encryption::CTS_Encryption(const std::string& cipher_name) :
BlockCipherMode(cipher_name, "CTS", block_size_of(cipher_name), 0, 2)
{
}
/*************************************************
* CTS Encryption Constructor *
*************************************************/
CTS_Encryption::CTS_Encryption(const std::string& cipher_name,
const SymmetricKey& key,
const InitializationVector& iv) :
BlockCipherMode(cipher_name, "CTS", block_size_of(cipher_name), 0, 2)
{
set_key(key);
set_iv(iv);
}
/*************************************************
* Encrypt a block *
*************************************************/
void CTS_Encryption::encrypt(const byte block[])
{
xor_buf(state, block, BLOCK_SIZE);
cipher->encrypt(state);
send(state, BLOCK_SIZE);
}
/*************************************************
* Encrypt in CTS mode *
*************************************************/
void CTS_Encryption::write(const byte input[], u32bit length)
{
u32bit copied = std::min(BUFFER_SIZE - position, length);
buffer.copy(position, input, copied);
length -= copied;
input += copied;
position += copied;
if(length == 0) return;
encrypt(buffer);
if(length > BLOCK_SIZE)
{
encrypt(buffer + BLOCK_SIZE);
while(length > 2*BLOCK_SIZE)
{
encrypt(input);
length -= BLOCK_SIZE;
input += BLOCK_SIZE;
}
position = 0;
}
else
{
copy_mem(buffer.begin(), buffer + BLOCK_SIZE, BLOCK_SIZE);
position = BLOCK_SIZE;
}
buffer.copy(position, input, length);
position += length;
}
/*************************************************
* Finish encrypting in CTS mode *
*************************************************/
void CTS_Encryption::end_msg()
{
if(position < BLOCK_SIZE + 1)
throw Exception("CTS_Encryption: insufficient data to encrypt");
xor_buf(state, buffer, BLOCK_SIZE);
cipher->encrypt(state);
SecureVector<byte> cn = state;
clear_mem(buffer + position, BUFFER_SIZE - position);
encrypt(buffer + BLOCK_SIZE);
send(cn, position - BLOCK_SIZE);
}
/*************************************************
* CTS Decryption Constructor *
*************************************************/
CTS_Decryption::CTS_Decryption(const std::string& cipher_name) :
BlockCipherMode(cipher_name, "CTS", block_size_of(cipher_name), 0, 2)
{
temp.create(BLOCK_SIZE);
}
/*************************************************
* CTS Decryption Constructor *
*************************************************/
CTS_Decryption::CTS_Decryption(const std::string& cipher_name,
const SymmetricKey& key,
const InitializationVector& iv) :
BlockCipherMode(cipher_name, "CTS", block_size_of(cipher_name), 0, 2)
{
temp.create(BLOCK_SIZE);
set_key(key);
set_iv(iv);
}
/*************************************************
* Decrypt a block *
*************************************************/
void CTS_Decryption::decrypt(const byte block[])
{
cipher->decrypt(block, temp);
xor_buf(temp, state, BLOCK_SIZE);
send(temp, BLOCK_SIZE);
state.copy(block, BLOCK_SIZE);
}
/*************************************************
* Decrypt in CTS mode *
*************************************************/
void CTS_Decryption::write(const byte input[], u32bit length)
{
u32bit copied = std::min(BUFFER_SIZE - position, length);
buffer.copy(position, input, copied);
length -= copied;
input += copied;
position += copied;
if(length == 0) return;
decrypt(buffer);
if(length > BLOCK_SIZE)
{
decrypt(buffer + BLOCK_SIZE);
while(length > 2*BLOCK_SIZE)
{
decrypt(input);
length -= BLOCK_SIZE;
input += BLOCK_SIZE;
}
position = 0;
}
else
{
copy_mem(buffer.begin(), buffer + BLOCK_SIZE, BLOCK_SIZE);
position = BLOCK_SIZE;
}
buffer.copy(position, input, length);
position += length;
}
/*************************************************
* Finish decrypting in CTS mode *
*************************************************/
void CTS_Decryption::end_msg()
{
cipher->decrypt(buffer, temp);
xor_buf(temp, buffer + BLOCK_SIZE, position - BLOCK_SIZE);
SecureVector<byte> xn = temp;
copy_mem(buffer + position, xn + (position - BLOCK_SIZE),
BUFFER_SIZE - position);
cipher->decrypt(buffer + BLOCK_SIZE, temp);
xor_buf(temp, state, BLOCK_SIZE);
send(temp, BLOCK_SIZE);
send(xn, position - BLOCK_SIZE);
}
}
|
