Crypto++  5.6.3
Free C++ class library of cryptographic schemes
skipjack.cpp
1 // skipjack.cpp - modified by Wei Dai from Paulo Barreto's skipjack32.c,
2 // which is public domain according to his web site.
3 
4 #include "pch.h"
5 
6 #ifndef CRYPTOPP_IMPORTS
7 
8 #include "skipjack.h"
9 
10 /*
11  * Optimized implementation of SKIPJACK algorithm
12  *
13  * originally written by Panu Rissanen <bande@lut.fi> 1998.06.24
14  * optimized by Mark Tillotson <markt@chaos.org.uk> 1998.06.25
15  * optimized by Paulo Barreto <pbarreto@nw.com.br> 1998.06.30
16  */
17 
18 NAMESPACE_BEGIN(CryptoPP)
19 
20 /**
21  * The F-table byte permutation (see description of the G-box permutation)
22  */
23 const byte SKIPJACK::Base::fTable[256] = {
24  0xa3,0xd7,0x09,0x83,0xf8,0x48,0xf6,0xf4,0xb3,0x21,0x15,0x78,0x99,0xb1,0xaf,0xf9,
25  0xe7,0x2d,0x4d,0x8a,0xce,0x4c,0xca,0x2e,0x52,0x95,0xd9,0x1e,0x4e,0x38,0x44,0x28,
26  0x0a,0xdf,0x02,0xa0,0x17,0xf1,0x60,0x68,0x12,0xb7,0x7a,0xc3,0xe9,0xfa,0x3d,0x53,
27  0x96,0x84,0x6b,0xba,0xf2,0x63,0x9a,0x19,0x7c,0xae,0xe5,0xf5,0xf7,0x16,0x6a,0xa2,
28  0x39,0xb6,0x7b,0x0f,0xc1,0x93,0x81,0x1b,0xee,0xb4,0x1a,0xea,0xd0,0x91,0x2f,0xb8,
29  0x55,0xb9,0xda,0x85,0x3f,0x41,0xbf,0xe0,0x5a,0x58,0x80,0x5f,0x66,0x0b,0xd8,0x90,
30  0x35,0xd5,0xc0,0xa7,0x33,0x06,0x65,0x69,0x45,0x00,0x94,0x56,0x6d,0x98,0x9b,0x76,
31  0x97,0xfc,0xb2,0xc2,0xb0,0xfe,0xdb,0x20,0xe1,0xeb,0xd6,0xe4,0xdd,0x47,0x4a,0x1d,
32  0x42,0xed,0x9e,0x6e,0x49,0x3c,0xcd,0x43,0x27,0xd2,0x07,0xd4,0xde,0xc7,0x67,0x18,
33  0x89,0xcb,0x30,0x1f,0x8d,0xc6,0x8f,0xaa,0xc8,0x74,0xdc,0xc9,0x5d,0x5c,0x31,0xa4,
34  0x70,0x88,0x61,0x2c,0x9f,0x0d,0x2b,0x87,0x50,0x82,0x54,0x64,0x26,0x7d,0x03,0x40,
35  0x34,0x4b,0x1c,0x73,0xd1,0xc4,0xfd,0x3b,0xcc,0xfb,0x7f,0xab,0xe6,0x3e,0x5b,0xa5,
36  0xad,0x04,0x23,0x9c,0x14,0x51,0x22,0xf0,0x29,0x79,0x71,0x7e,0xff,0x8c,0x0e,0xe2,
37  0x0c,0xef,0xbc,0x72,0x75,0x6f,0x37,0xa1,0xec,0xd3,0x8e,0x62,0x8b,0x86,0x10,0xe8,
38  0x08,0x77,0x11,0xbe,0x92,0x4f,0x24,0xc5,0x32,0x36,0x9d,0xcf,0xf3,0xa6,0xbb,0xac,
39  0x5e,0x6c,0xa9,0x13,0x57,0x25,0xb5,0xe3,0xbd,0xa8,0x3a,0x01,0x05,0x59,0x2a,0x46
40 };
41 
42 /**
43  * The key-dependent permutation G on V^16 is a four-round Feistel network.
44  * The round function is a fixed byte-substitution table (permutation on V^8),
45  * the F-table. Each round of G incorporates a single byte from the key.
46  */
47 #define g(tab, w, i, j, k, l) \
48 { \
49  w ^= (word)tab[i*256 + (w & 0xff)] << 8; \
50  w ^= (word)tab[j*256 + (w >> 8)]; \
51  w ^= (word)tab[k*256 + (w & 0xff)] << 8; \
52  w ^= (word)tab[l*256 + (w >> 8)]; \
53 }
54 
55 #define g0(tab, w) g(tab, w, 0, 1, 2, 3)
56 #define g1(tab, w) g(tab, w, 4, 5, 6, 7)
57 #define g2(tab, w) g(tab, w, 8, 9, 0, 1)
58 #define g3(tab, w) g(tab, w, 2, 3, 4, 5)
59 #define g4(tab, w) g(tab, w, 6, 7, 8, 9)
60 
61 /**
62  * The inverse of the G permutation.
63  */
64 #define h(tab, w, i, j, k, l) \
65 { \
66  w ^= (word)tab[l*256 + (w >> 8)]; \
67  w ^= (word)tab[k*256 + (w & 0xff)] << 8; \
68  w ^= (word)tab[j*256 + (w >> 8)]; \
69  w ^= (word)tab[i*256 + (w & 0xff)] << 8; \
70 }
71 
72 #define h0(tab, w) h(tab, w, 0, 1, 2, 3)
73 #define h1(tab, w) h(tab, w, 4, 5, 6, 7)
74 #define h2(tab, w) h(tab, w, 8, 9, 0, 1)
75 #define h3(tab, w) h(tab, w, 2, 3, 4, 5)
76 #define h4(tab, w) h(tab, w, 6, 7, 8, 9)
77 
78 /**
79  * Preprocess a user key into a table to save an XOR at each F-table access.
80  */
81 void SKIPJACK::Base::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &)
82 {
83  AssertValidKeyLength(length);
84 
85  /* tab[i][c] = fTable[c ^ key[i]] */
86  int i;
87  for (i = 0; i < 10; i++) {
88  byte *t = tab+i*256, k = key[9-i];
89  int c;
90  for (c = 0; c < 256; c++) {
91  t[c] = fTable[c ^ k];
92  }
93  }
94 }
95 
97 
98 /**
99  * Encrypt a single block of data.
100  */
101 void SKIPJACK::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
102 {
103  word16 w1, w2, w3, w4;
104  Block::Get(inBlock)(w4)(w3)(w2)(w1);
105 
106  /* stepping rule A: */
107  g0(tab, w1); w4 ^= w1 ^ 1;
108  g1(tab, w4); w3 ^= w4 ^ 2;
109  g2(tab, w3); w2 ^= w3 ^ 3;
110  g3(tab, w2); w1 ^= w2 ^ 4;
111  g4(tab, w1); w4 ^= w1 ^ 5;
112  g0(tab, w4); w3 ^= w4 ^ 6;
113  g1(tab, w3); w2 ^= w3 ^ 7;
114  g2(tab, w2); w1 ^= w2 ^ 8;
115 
116  /* stepping rule B: */
117  w2 ^= w1 ^ 9; g3(tab, w1);
118  w1 ^= w4 ^ 10; g4(tab, w4);
119  w4 ^= w3 ^ 11; g0(tab, w3);
120  w3 ^= w2 ^ 12; g1(tab, w2);
121  w2 ^= w1 ^ 13; g2(tab, w1);
122  w1 ^= w4 ^ 14; g3(tab, w4);
123  w4 ^= w3 ^ 15; g4(tab, w3);
124  w3 ^= w2 ^ 16; g0(tab, w2);
125 
126  /* stepping rule A: */
127  g1(tab, w1); w4 ^= w1 ^ 17;
128  g2(tab, w4); w3 ^= w4 ^ 18;
129  g3(tab, w3); w2 ^= w3 ^ 19;
130  g4(tab, w2); w1 ^= w2 ^ 20;
131  g0(tab, w1); w4 ^= w1 ^ 21;
132  g1(tab, w4); w3 ^= w4 ^ 22;
133  g2(tab, w3); w2 ^= w3 ^ 23;
134  g3(tab, w2); w1 ^= w2 ^ 24;
135 
136  /* stepping rule B: */
137  w2 ^= w1 ^ 25; g4(tab, w1);
138  w1 ^= w4 ^ 26; g0(tab, w4);
139  w4 ^= w3 ^ 27; g1(tab, w3);
140  w3 ^= w2 ^ 28; g2(tab, w2);
141  w2 ^= w1 ^ 29; g3(tab, w1);
142  w1 ^= w4 ^ 30; g4(tab, w4);
143  w4 ^= w3 ^ 31; g0(tab, w3);
144  w3 ^= w2 ^ 32; g1(tab, w2);
145 
146  Block::Put(xorBlock, outBlock)(w4)(w3)(w2)(w1);
147 }
148 
149 /**
150  * Decrypt a single block of data.
151  */
152 void SKIPJACK::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
153 {
154  word16 w1, w2, w3, w4;
155  Block::Get(inBlock)(w4)(w3)(w2)(w1);
156 
157  /* stepping rule A: */
158  h1(tab, w2); w3 ^= w2 ^ 32;
159  h0(tab, w3); w4 ^= w3 ^ 31;
160  h4(tab, w4); w1 ^= w4 ^ 30;
161  h3(tab, w1); w2 ^= w1 ^ 29;
162  h2(tab, w2); w3 ^= w2 ^ 28;
163  h1(tab, w3); w4 ^= w3 ^ 27;
164  h0(tab, w4); w1 ^= w4 ^ 26;
165  h4(tab, w1); w2 ^= w1 ^ 25;
166 
167  /* stepping rule B: */
168  w1 ^= w2 ^ 24; h3(tab, w2);
169  w2 ^= w3 ^ 23; h2(tab, w3);
170  w3 ^= w4 ^ 22; h1(tab, w4);
171  w4 ^= w1 ^ 21; h0(tab, w1);
172  w1 ^= w2 ^ 20; h4(tab, w2);
173  w2 ^= w3 ^ 19; h3(tab, w3);
174  w3 ^= w4 ^ 18; h2(tab, w4);
175  w4 ^= w1 ^ 17; h1(tab, w1);
176 
177  /* stepping rule A: */
178  h0(tab, w2); w3 ^= w2 ^ 16;
179  h4(tab, w3); w4 ^= w3 ^ 15;
180  h3(tab, w4); w1 ^= w4 ^ 14;
181  h2(tab, w1); w2 ^= w1 ^ 13;
182  h1(tab, w2); w3 ^= w2 ^ 12;
183  h0(tab, w3); w4 ^= w3 ^ 11;
184  h4(tab, w4); w1 ^= w4 ^ 10;
185  h3(tab, w1); w2 ^= w1 ^ 9;
186 
187  /* stepping rule B: */
188  w1 ^= w2 ^ 8; h2(tab, w2);
189  w2 ^= w3 ^ 7; h1(tab, w3);
190  w3 ^= w4 ^ 6; h0(tab, w4);
191  w4 ^= w1 ^ 5; h4(tab, w1);
192  w1 ^= w2 ^ 4; h3(tab, w2);
193  w2 ^= w3 ^ 3; h2(tab, w3);
194  w3 ^= w4 ^ 2; h1(tab, w4);
195  w4 ^= w1 ^ 1; h0(tab, w1);
196 
197  Block::Put(xorBlock, outBlock)(w4)(w3)(w2)(w1);
198 }
199 
200 NAMESPACE_END
201 
202 #endif
Access a block of memory.
Definition: misc.h:2190
Classes for the SKIPJACK block cipher.
Access a block of memory.
Definition: misc.h:2152
SKIPJACK block cipher information.
Definition: skipjack.h:24
Crypto++ library namespace.
Interface for retrieving values given their names.
Definition: cryptlib.h:277