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
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
// idea.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#include "idea.h"
#include "misc.h"
NAMESPACE_BEGIN(CryptoPP)
static const int IDEA_KEYLEN=(6*IDEA::ROUNDS+4); // key schedule length in # of word16s
#define low16(x) ((x)&0xffff) // compiler should be able to optimize this away if word is 16 bits
#define high16(x) ((x)>>16)
CRYPTOPP_COMPILE_ASSERT(sizeof(IDEA::Word) >= 2);
// should use an inline function but macros are still faster in MSVC 4.0
#define DirectMUL(a,b) \
{ \
assert(b <= 0xffff); \
\
word32 p=(word32)low16(a)*b; \
\
if (p) \
{ \
p = low16(p) - high16(p); \
a = (IDEA::Word)p - (IDEA::Word)high16(p); \
} \
else \
a = 1-a-b; \
}
#ifdef IDEA_LARGECACHE
bool IDEA::Base::tablesBuilt = false;
word16 IDEA::Base::log[0x10000];
word16 IDEA::Base::antilog[0x10000];
void IDEA::Base::BuildLogTables()
{
if (tablesBuilt)
return;
else
{
tablesBuilt = true;
IDEA::Word x=1;
word32 i;
for (i=0; i<0x10000; i++)
{
antilog[i] = (word16)x;
DirectMUL(x, 3);
}
for (i=0; i<0x10000; i++)
log[antilog[i]] = (word16)i;
}
}
void IDEA::Base::LookupKeyLogs()
{
IDEA::Word* Z=key;
int r=ROUNDS;
do
{
Z[0] = log[Z[0]];
Z[3] = log[Z[3]];
Z[4] = log[Z[4]];
Z[5] = log[Z[5]];
Z+=6;
} while (--r);
Z[0] = log[Z[0]];
Z[3] = log[Z[3]];
}
inline void IDEA::Base::LookupMUL(IDEA::Word &a, IDEA::Word b)
{
a = antilog[low16(log[low16(a)]+b)];
}
#endif // IDEA_LARGECACHE
void IDEA::Base::UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &)
{
AssertValidKeyLength(length);
#ifdef IDEA_LARGECACHE
BuildLogTables();
#endif
EnKey(userKey);
if (!IsForwardTransformation())
DeKey();
#ifdef IDEA_LARGECACHE
LookupKeyLogs();
#endif
}
void IDEA::Base::EnKey (const byte *userKey)
{
unsigned int i;
for (i=0; i<8; i++)
m_key[i] = ((IDEA::Word)userKey[2*i]<<8) | userKey[2*i+1];
for (; i<IDEA_KEYLEN; i++)
{
unsigned int j = RoundDownToMultipleOf(i,8U)-8;
m_key[i] = low16((m_key[j+(i+1)%8] << 9) | (m_key[j+(i+2)%8] >> 7));
}
}
static IDEA::Word MulInv(IDEA::Word x)
{
IDEA::Word y=x;
for (unsigned i=0; i<15; i++)
{
DirectMUL(y,low16(y));
DirectMUL(y,x);
}
return low16(y);
}
static inline IDEA::Word AddInv(IDEA::Word x)
{
return low16(0-x);
}
void IDEA::Base::DeKey()
{
FixedSizeSecBlock<IDEA::Word, 6*ROUNDS+4> tempkey;
unsigned int i;
for (i=0; i<ROUNDS; i++)
{
tempkey[i*6+0] = MulInv(m_key[(ROUNDS-i)*6+0]);
tempkey[i*6+1] = AddInv(m_key[(ROUNDS-i)*6+1+(i>0)]);
tempkey[i*6+2] = AddInv(m_key[(ROUNDS-i)*6+2-(i>0)]);
tempkey[i*6+3] = MulInv(m_key[(ROUNDS-i)*6+3]);
tempkey[i*6+4] = m_key[(ROUNDS-1-i)*6+4];
tempkey[i*6+5] = m_key[(ROUNDS-1-i)*6+5];
}
tempkey[i*6+0] = MulInv(m_key[(ROUNDS-i)*6+0]);
tempkey[i*6+1] = AddInv(m_key[(ROUNDS-i)*6+1]);
tempkey[i*6+2] = AddInv(m_key[(ROUNDS-i)*6+2]);
tempkey[i*6+3] = MulInv(m_key[(ROUNDS-i)*6+3]);
m_key = tempkey;
}
#ifdef IDEA_LARGECACHE
#define MUL(a,b) LookupMUL(a,b)
#else
#define MUL(a,b) DirectMUL(a,b)
#endif
void IDEA::Base::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
typedef BlockGetAndPut<word16, BigEndian> Block;
const IDEA::Word *key = m_key;
IDEA::Word x0,x1,x2,x3,t0,t1;
Block::Get(inBlock)(x0)(x1)(x2)(x3);
for (unsigned int i=0; i<ROUNDS; i++)
{
MUL(x0, key[i*6+0]);
x1 += key[i*6+1];
x2 += key[i*6+2];
MUL(x3, key[i*6+3]);
t0 = x0^x2;
MUL(t0, key[i*6+4]);
t1 = t0 + (x1^x3);
MUL(t1, key[i*6+5]);
t0 += t1;
x0 ^= t1;
x3 ^= t0;
t0 ^= x1;
x1 = x2^t1;
x2 = t0;
}
MUL(x0, key[ROUNDS*6+0]);
x2 += key[ROUNDS*6+1];
x1 += key[ROUNDS*6+2];
MUL(x3, key[ROUNDS*6+3]);
Block::Put(xorBlock, outBlock)(x0)(x2)(x1)(x3);
}
NAMESPACE_END
|
