Botan  1.10.9
cast256.cpp
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1 /*
2 * CAST-256
3 * (C) 1999-2007 Jack Lloyd
4 *
5 * Distributed under the terms of the Botan license
6 */
7 
8 #include <botan/cast256.h>
9 #include <botan/loadstor.h>
10 #include <botan/rotate.h>
11 
12 namespace Botan {
13 
14 namespace {
15 
16 /*
17 * CAST-256 Round Type 1
18 */
19 void round1(u32bit& out, u32bit in, u32bit mask, u32bit rot)
20  {
21  u32bit temp = rotate_left(mask + in, rot);
22  out ^= (CAST_SBOX1[get_byte(0, temp)] ^ CAST_SBOX2[get_byte(1, temp)]) -
23  CAST_SBOX3[get_byte(2, temp)] + CAST_SBOX4[get_byte(3, temp)];
24  }
25 
26 /*
27 * CAST-256 Round Type 2
28 */
29 void round2(u32bit& out, u32bit in, u32bit mask, u32bit rot)
30  {
31  u32bit temp = rotate_left(mask ^ in, rot);
32  out ^= (CAST_SBOX1[get_byte(0, temp)] - CAST_SBOX2[get_byte(1, temp)] +
33  CAST_SBOX3[get_byte(2, temp)]) ^ CAST_SBOX4[get_byte(3, temp)];
34  }
35 
36 /*
37 * CAST-256 Round Type 3
38 */
39 void round3(u32bit& out, u32bit in, u32bit mask, u32bit rot)
40  {
41  u32bit temp = rotate_left(mask - in, rot);
42  out ^= ((CAST_SBOX1[get_byte(0, temp)] + CAST_SBOX2[get_byte(1, temp)]) ^
43  CAST_SBOX3[get_byte(2, temp)]) - CAST_SBOX4[get_byte(3, temp)];
44  }
45 
46 }
47 
48 /*
49 * CAST-256 Encryption
50 */
51 void CAST_256::encrypt_n(const byte in[], byte out[], size_t blocks) const
52  {
53  for(size_t i = 0; i != blocks; ++i)
54  {
55  u32bit A = load_be<u32bit>(in, 0);
56  u32bit B = load_be<u32bit>(in, 1);
57  u32bit C = load_be<u32bit>(in, 2);
58  u32bit D = load_be<u32bit>(in, 3);
59 
60  round1(C, D, MK[ 0], RK[ 0]); round2(B, C, MK[ 1], RK[ 1]);
61  round3(A, B, MK[ 2], RK[ 2]); round1(D, A, MK[ 3], RK[ 3]);
62  round1(C, D, MK[ 4], RK[ 4]); round2(B, C, MK[ 5], RK[ 5]);
63  round3(A, B, MK[ 6], RK[ 6]); round1(D, A, MK[ 7], RK[ 7]);
64  round1(C, D, MK[ 8], RK[ 8]); round2(B, C, MK[ 9], RK[ 9]);
65  round3(A, B, MK[10], RK[10]); round1(D, A, MK[11], RK[11]);
66  round1(C, D, MK[12], RK[12]); round2(B, C, MK[13], RK[13]);
67  round3(A, B, MK[14], RK[14]); round1(D, A, MK[15], RK[15]);
68  round1(C, D, MK[16], RK[16]); round2(B, C, MK[17], RK[17]);
69  round3(A, B, MK[18], RK[18]); round1(D, A, MK[19], RK[19]);
70  round1(C, D, MK[20], RK[20]); round2(B, C, MK[21], RK[21]);
71  round3(A, B, MK[22], RK[22]); round1(D, A, MK[23], RK[23]);
72  round1(D, A, MK[27], RK[27]); round3(A, B, MK[26], RK[26]);
73  round2(B, C, MK[25], RK[25]); round1(C, D, MK[24], RK[24]);
74  round1(D, A, MK[31], RK[31]); round3(A, B, MK[30], RK[30]);
75  round2(B, C, MK[29], RK[29]); round1(C, D, MK[28], RK[28]);
76  round1(D, A, MK[35], RK[35]); round3(A, B, MK[34], RK[34]);
77  round2(B, C, MK[33], RK[33]); round1(C, D, MK[32], RK[32]);
78  round1(D, A, MK[39], RK[39]); round3(A, B, MK[38], RK[38]);
79  round2(B, C, MK[37], RK[37]); round1(C, D, MK[36], RK[36]);
80  round1(D, A, MK[43], RK[43]); round3(A, B, MK[42], RK[42]);
81  round2(B, C, MK[41], RK[41]); round1(C, D, MK[40], RK[40]);
82  round1(D, A, MK[47], RK[47]); round3(A, B, MK[46], RK[46]);
83  round2(B, C, MK[45], RK[45]); round1(C, D, MK[44], RK[44]);
84 
85  store_be(out, A, B, C, D);
86 
87  in += BLOCK_SIZE;
88  out += BLOCK_SIZE;
89  }
90  }
91 
92 /*
93 * CAST-256 Decryption
94 */
95 void CAST_256::decrypt_n(const byte in[], byte out[], size_t blocks) const
96  {
97  for(size_t i = 0; i != blocks; ++i)
98  {
99  u32bit A = load_be<u32bit>(in, 0);
100  u32bit B = load_be<u32bit>(in, 1);
101  u32bit C = load_be<u32bit>(in, 2);
102  u32bit D = load_be<u32bit>(in, 3);
103 
104  round1(C, D, MK[44], RK[44]); round2(B, C, MK[45], RK[45]);
105  round3(A, B, MK[46], RK[46]); round1(D, A, MK[47], RK[47]);
106  round1(C, D, MK[40], RK[40]); round2(B, C, MK[41], RK[41]);
107  round3(A, B, MK[42], RK[42]); round1(D, A, MK[43], RK[43]);
108  round1(C, D, MK[36], RK[36]); round2(B, C, MK[37], RK[37]);
109  round3(A, B, MK[38], RK[38]); round1(D, A, MK[39], RK[39]);
110  round1(C, D, MK[32], RK[32]); round2(B, C, MK[33], RK[33]);
111  round3(A, B, MK[34], RK[34]); round1(D, A, MK[35], RK[35]);
112  round1(C, D, MK[28], RK[28]); round2(B, C, MK[29], RK[29]);
113  round3(A, B, MK[30], RK[30]); round1(D, A, MK[31], RK[31]);
114  round1(C, D, MK[24], RK[24]); round2(B, C, MK[25], RK[25]);
115  round3(A, B, MK[26], RK[26]); round1(D, A, MK[27], RK[27]);
116  round1(D, A, MK[23], RK[23]); round3(A, B, MK[22], RK[22]);
117  round2(B, C, MK[21], RK[21]); round1(C, D, MK[20], RK[20]);
118  round1(D, A, MK[19], RK[19]); round3(A, B, MK[18], RK[18]);
119  round2(B, C, MK[17], RK[17]); round1(C, D, MK[16], RK[16]);
120  round1(D, A, MK[15], RK[15]); round3(A, B, MK[14], RK[14]);
121  round2(B, C, MK[13], RK[13]); round1(C, D, MK[12], RK[12]);
122  round1(D, A, MK[11], RK[11]); round3(A, B, MK[10], RK[10]);
123  round2(B, C, MK[ 9], RK[ 9]); round1(C, D, MK[ 8], RK[ 8]);
124  round1(D, A, MK[ 7], RK[ 7]); round3(A, B, MK[ 6], RK[ 6]);
125  round2(B, C, MK[ 5], RK[ 5]); round1(C, D, MK[ 4], RK[ 4]);
126  round1(D, A, MK[ 3], RK[ 3]); round3(A, B, MK[ 2], RK[ 2]);
127  round2(B, C, MK[ 1], RK[ 1]); round1(C, D, MK[ 0], RK[ 0]);
128 
129  store_be(out, A, B, C, D);
130 
131  in += BLOCK_SIZE;
132  out += BLOCK_SIZE;
133  }
134  }
135 
136 /*
137 * CAST-256 Key Schedule
138 */
139 void CAST_256::key_schedule(const byte key[], size_t length)
140  {
142  for(size_t j = 0; j != length; ++j)
143  K[j/4] = (K[j/4] << 8) + key[j];
144 
145  u32bit A = K[0], B = K[1], C = K[2], D = K[3],
146  E = K[4], F = K[5], G = K[6], H = K[7];
147 
148  for(size_t j = 0; j != 48; j += 4)
149  {
150  round1(G, H, KEY_MASK[4*j+ 0], KEY_ROT[(4*j+ 0) % 32]);
151  round2(F, G, KEY_MASK[4*j+ 1], KEY_ROT[(4*j+ 1) % 32]);
152  round3(E, F, KEY_MASK[4*j+ 2], KEY_ROT[(4*j+ 2) % 32]);
153  round1(D, E, KEY_MASK[4*j+ 3], KEY_ROT[(4*j+ 3) % 32]);
154  round2(C, D, KEY_MASK[4*j+ 4], KEY_ROT[(4*j+ 4) % 32]);
155  round3(B, C, KEY_MASK[4*j+ 5], KEY_ROT[(4*j+ 5) % 32]);
156  round1(A, B, KEY_MASK[4*j+ 6], KEY_ROT[(4*j+ 6) % 32]);
157  round2(H, A, KEY_MASK[4*j+ 7], KEY_ROT[(4*j+ 7) % 32]);
158  round1(G, H, KEY_MASK[4*j+ 8], KEY_ROT[(4*j+ 8) % 32]);
159  round2(F, G, KEY_MASK[4*j+ 9], KEY_ROT[(4*j+ 9) % 32]);
160  round3(E, F, KEY_MASK[4*j+10], KEY_ROT[(4*j+10) % 32]);
161  round1(D, E, KEY_MASK[4*j+11], KEY_ROT[(4*j+11) % 32]);
162  round2(C, D, KEY_MASK[4*j+12], KEY_ROT[(4*j+12) % 32]);
163  round3(B, C, KEY_MASK[4*j+13], KEY_ROT[(4*j+13) % 32]);
164  round1(A, B, KEY_MASK[4*j+14], KEY_ROT[(4*j+14) % 32]);
165  round2(H, A, KEY_MASK[4*j+15], KEY_ROT[(4*j+15) % 32]);
166 
167  RK[j ] = (A % 32);
168  RK[j+1] = (C % 32);
169  RK[j+2] = (E % 32);
170  RK[j+3] = (G % 32);
171  MK[j ] = H;
172  MK[j+1] = F;
173  MK[j+2] = D;
174  MK[j+3] = B;
175  }
176  }
177 
178 }
const u32bit CAST_SBOX2[256]
Definition: cast256.h:40
const u32bit CAST_SBOX1[256]
Definition: cast256.h:39
T rotate_left(T input, size_t rot)
Definition: rotate.h:21
byte get_byte(size_t byte_num, T input)
Definition: get_byte.h:21
void encrypt_n(const byte in[], byte out[], size_t blocks) const
Definition: cast256.cpp:51
unsigned char byte
Definition: types.h:22
const u32bit CAST_SBOX4[256]
Definition: cast256.h:42
u32bit load_be< u32bit >(const byte in[], size_t off)
Definition: loadstor.h:166
void decrypt_n(const byte in[], byte out[], size_t blocks) const
Definition: cast256.cpp:95
void store_be(u16bit in, byte out[2])
Definition: loadstor.h:412
unsigned int u32bit
Definition: types.h:32
const u32bit CAST_SBOX3[256]
Definition: cast256.h:41