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
|
/*************************************************
* OFB Mode Source File *
* (C) 1999-2007 The Botan Project *
*************************************************/
#include <botan/ofb.h>
#include <botan/lookup.h>
#include <botan/bit_ops.h>
#include <algorithm>
namespace Botan {
/*************************************************
* OFB Constructor *
*************************************************/
OFB::OFB(const std::string& cipher_name) :
BlockCipherMode(cipher_name, "OFB", block_size_of(cipher_name), 2)
{
}
/*************************************************
* OFB Constructor *
*************************************************/
OFB::OFB(const std::string& cipher_name, const SymmetricKey& key,
const InitializationVector& iv) :
BlockCipherMode(cipher_name, "OFB", block_size_of(cipher_name), 2)
{
set_key(key);
set_iv(iv);
}
/*************************************************
* OFB Encryption/Decryption *
*************************************************/
void OFB::write(const byte input[], u32bit length)
{
u32bit copied = std::min(BLOCK_SIZE - position, length);
xor_buf(buffer, input, state + position, copied);
send(buffer, copied);
input += copied;
length -= copied;
position += copied;
if(position == BLOCK_SIZE)
{
cipher->encrypt(state);
position = 0;
}
while(length >= BLOCK_SIZE)
{
xor_buf(buffer, input, state, BLOCK_SIZE);
send(buffer, BLOCK_SIZE);
input += BLOCK_SIZE;
length -= BLOCK_SIZE;
cipher->encrypt(state);
}
xor_buf(buffer, input, state + position, length);
send(buffer, length);
position += length;
}
}
|
