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
|
/*
* RC6
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/internal/block_utils.h>
#include <botan/rc6.h>
namespace Botan {
BOTAN_REGISTER_BLOCK_CIPHER_NOARGS(RC6);
/*
* RC6 Encryption
*/
void RC6::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);
u32bit C = load_le<u32bit>(in, 2);
u32bit D = load_le<u32bit>(in, 3);
B += S[0]; D += S[1];
for(size_t j = 0; j != 20; j += 4)
{
u32bit T1, T2;
T1 = rotate_left(B*(2*B+1), 5);
T2 = rotate_left(D*(2*D+1), 5);
A = rotate_left(A ^ T1, T2 % 32) + S[2*j+2];
C = rotate_left(C ^ T2, T1 % 32) + S[2*j+3];
T1 = rotate_left(C*(2*C+1), 5);
T2 = rotate_left(A*(2*A+1), 5);
B = rotate_left(B ^ T1, T2 % 32) + S[2*j+4];
D = rotate_left(D ^ T2, T1 % 32) + S[2*j+5];
T1 = rotate_left(D*(2*D+1), 5);
T2 = rotate_left(B*(2*B+1), 5);
C = rotate_left(C ^ T1, T2 % 32) + S[2*j+6];
A = rotate_left(A ^ T2, T1 % 32) + S[2*j+7];
T1 = rotate_left(A*(2*A+1), 5);
T2 = rotate_left(C*(2*C+1), 5);
D = rotate_left(D ^ T1, T2 % 32) + S[2*j+8];
B = rotate_left(B ^ T2, T1 % 32) + S[2*j+9];
}
A += S[42]; C += S[43];
store_le(out, A, B, C, D);
in += BLOCK_SIZE;
out += BLOCK_SIZE;
}
}
/*
* RC6 Decryption
*/
void RC6::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);
u32bit C = load_le<u32bit>(in, 2);
u32bit D = load_le<u32bit>(in, 3);
C -= S[43]; A -= S[42];
for(size_t j = 0; j != 20; j += 4)
{
u32bit T1, T2;
T1 = rotate_left(A*(2*A+1), 5);
T2 = rotate_left(C*(2*C+1), 5);
B = rotate_right(B - S[41 - 2*j], T1 % 32) ^ T2;
D = rotate_right(D - S[40 - 2*j], T2 % 32) ^ T1;
T1 = rotate_left(D*(2*D+1), 5);
T2 = rotate_left(B*(2*B+1), 5);
A = rotate_right(A - S[39 - 2*j], T1 % 32) ^ T2;
C = rotate_right(C - S[38 - 2*j], T2 % 32) ^ T1;
T1 = rotate_left(C*(2*C+1), 5);
T2 = rotate_left(A*(2*A+1), 5);
D = rotate_right(D - S[37 - 2*j], T1 % 32) ^ T2;
B = rotate_right(B - S[36 - 2*j], T2 % 32) ^ T1;
T1 = rotate_left(B*(2*B+1), 5);
T2 = rotate_left(D*(2*D+1), 5);
C = rotate_right(C - S[35 - 2*j], T1 % 32) ^ T2;
A = rotate_right(A - S[34 - 2*j], T2 % 32) ^ T1;
}
D -= S[1]; B -= S[0];
store_le(out, A, B, C, D);
in += BLOCK_SIZE;
out += BLOCK_SIZE;
}
}
/*
* RC6 Key Schedule
*/
void RC6::key_schedule(const byte key[], size_t length)
{
S.resize(44);
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 RC6::clear()
{
zap(S);
}
}
|
