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
|
/*
* RC5
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/rc5.h>
#include <botan/loadstor.h>
#include <botan/rotate.h>
#include <botan/parsing.h>
#include <algorithm>
namespace Botan {
/*
* RC5 Encryption
*/
void RC5::encrypt_n(const byte in[], byte out[], size_t blocks) const
{
for(size_t i = 0; i != blocks; ++i)
{
u32bit A = load_le<u32bit>(in, 0);
u32bit B = load_le<u32bit>(in, 1);
A += S[0]; B += S[1];
for(size_t j = 0; j != rounds; j += 4)
{
A = rotate_left(A ^ B, B % 32) + S[2*j+2];
B = rotate_left(B ^ A, A % 32) + S[2*j+3];
A = rotate_left(A ^ B, B % 32) + S[2*j+4];
B = rotate_left(B ^ A, A % 32) + S[2*j+5];
A = rotate_left(A ^ B, B % 32) + S[2*j+6];
B = rotate_left(B ^ A, A % 32) + S[2*j+7];
A = rotate_left(A ^ B, B % 32) + S[2*j+8];
B = rotate_left(B ^ A, A % 32) + S[2*j+9];
}
store_le(out, A, B);
in += BLOCK_SIZE;
out += BLOCK_SIZE;
}
}
/*
* RC5 Decryption
*/
void RC5::decrypt_n(const byte in[], byte out[], size_t blocks) const
{
for(size_t i = 0; i != blocks; ++i)
{
u32bit A = load_le<u32bit>(in, 0);
u32bit B = load_le<u32bit>(in, 1);
for(size_t j = rounds; j != 0; j -= 4)
{
B = rotate_right(B - S[2*j+1], A % 32) ^ A;
A = rotate_right(A - S[2*j ], B % 32) ^ B;
B = rotate_right(B - S[2*j-1], A % 32) ^ A;
A = rotate_right(A - S[2*j-2], B % 32) ^ B;
B = rotate_right(B - S[2*j-3], A % 32) ^ A;
A = rotate_right(A - S[2*j-4], B % 32) ^ B;
B = rotate_right(B - S[2*j-5], A % 32) ^ A;
A = rotate_right(A - S[2*j-6], B % 32) ^ B;
}
B -= S[1]; A -= S[0];
store_le(out, A, B);
in += BLOCK_SIZE;
out += BLOCK_SIZE;
}
}
/*
* RC5 Key Schedule
*/
void RC5::key_schedule(const byte key[], size_t length)
{
S.resize(2*rounds + 2);
const size_t WORD_KEYLENGTH = (((length - 1) / 4) + 1);
const size_t MIX_ROUNDS = 3 * std::max(WORD_KEYLENGTH, S.size());
S[0] = 0xB7E15163;
for(size_t i = 1; i != S.size(); ++i)
S[i] = S[i-1] + 0x9E3779B9;
secure_vector<u32bit> K(8);
for(s32bit i = length-1; i >= 0; --i)
K[i/4] = (K[i/4] << 8) + key[i];
u32bit A = 0, B = 0;
for(size_t i = 0; i != MIX_ROUNDS; ++i)
{
A = rotate_left(S[i % S.size()] + A + B, 3);
B = rotate_left(K[i % WORD_KEYLENGTH] + A + B, (A + B) % 32);
S[i % S.size()] = A;
K[i % WORD_KEYLENGTH] = B;
}
}
void RC5::clear()
{
zap(S);
}
/*
* Return the name of this type
*/
std::string RC5::name() const
{
return "RC5(" + std::to_string(rounds) + ")";
}
/*
* RC5 Constructor
*/
RC5::RC5(size_t r) : rounds(r)
{
if(rounds < 8 || rounds > 32 || (rounds % 4 != 0))
throw Invalid_Argument("RC5: Invalid number of rounds " +
std::to_string(rounds));
}
}
|
