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[arm-crypto-lib.git] / cscipher / cscipher_small.c
1 /* cscipher_small_core.c */
2 /*
3     This file is part of the ARM-Crypto-Lib.
4     Copyright (C) 2006-2010 Daniel Otte (daniel.otte@rub.de)
5
6     This program is free software: you can redistribute it and/or modify
7     it under the terms of the GNU General Public License as published by
8     the Free Software Foundation, either version 3 of the License, or
9     (at your option) any later version.
10
11     This program is distributed in the hope that it will be useful,
12     but WITHOUT ANY WARRANTY; without even the implied warranty of
13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14     GNU General Public License for more details.
15
16     You should have received a copy of the GNU General Public License
17     along with this program.  If not, see <http://www.gnu.org/licenses/>.
18 */
19
20 #include <stdint.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include "memxor.h"
24 #include "cscipher.h"
25
26 #define DEBUG 0
27
28 #if DEBUG
29 #include "cli.h"
30 #endif
31
32 #define ROTL(a) (((a)<<1)|((a)>>7))
33
34 #ifndef SBOX_PROG
35 #define SBOX_PROG 0
36 #endif
37
38 #if SBOX_PROG
39 static const uint8_t fg_table[] = {
40                 0xfa, 0xd6, 0xb0, 0xb2, 0x7b, 0x5e, 0x71, 0x78,
41                 0xed, 0xd4, 0xa5, 0xb3, 0xef, 0xdc, 0xe7, 0xf9
42 };
43
44 static
45 uint8_t p(uint8_t a){
46         a ^= fg_table[a&0xf]&0xf0;
47         a ^= fg_table[a>>4] &0x0f;
48         a ^= fg_table[a&0xf]&0xf0;
49         return a;
50 }
51 #define P(a) p(a)
52
53 #else
54
55 #include "cscipher_sbox.h"
56 #define P(a) (cscipher_sbox[(a)])
57 #endif
58
59 static const uint8_t round_const[] = {
60         0xb7, 0xe1, 0x51, 0x62, 0x8a, 0xed, 0x2a, 0x6a,
61         0xbf, 0x71, 0x58, 0x80, 0x9c, 0xf4, 0xf3, 0xc7 };
62
63 static const uint8_t ks_const[] = {
64         0x29,0x0d,0x61,0x40,0x9c,0xeb,0x9e,0x8f,
65         0x1f,0x85,0x5f,0x58,0x5b,0x01,0x39,0x86,
66         0x97,0x2e,0xd7,0xd6,0x35,0xae,0x17,0x16,
67         0x21,0xb6,0x69,0x4e,0xa5,0x72,0x87,0x08,
68         0x3c,0x18,0xe6,0xe7,0xfa,0xad,0xb8,0x89,
69         0xb7,0x00,0xf7,0x6f,0x73,0x84,0x11,0x63,
70         0x3f,0x96,0x7f,0x6e,0xbf,0x14,0x9d,0xac,
71         0xa4,0x0e,0x7e,0xf6,0x20,0x4a,0x62,0x30,
72         0x03,0xc5,0x4b,0x5a,0x46,0xa3,0x44,0x65
73 };
74
75 static uint16_t m(uint16_t a){
76         uint8_t xl, xr, yl, yr;
77         uint16_t ret;
78         xr = a>>8;
79         xl = a&0xff;
80         yl = (ROTL(xl)&0x55)^xl^xr;
81         yr = ROTL(xl)^xr;
82         ret = (P(yr)<<8)|P(yl);
83         return ret;
84 }
85
86 static uint16_t m_inv(uint16_t a){
87         uint8_t xl, xr;
88         xr = P(a>>8);
89         xl = P(a&0xff);
90         xl ^= xr;
91         xl ^= (ROTL(xl)&0xaa);
92         xr ^= ROTL(xl);
93         return (xr<<8)|xl;
94 }
95
96
97 void cscipher_enc(void* buffer, const cscipher_ctx_t* ctx){
98         uint8_t i,j,k;
99         uint8_t tmp[8];
100         for(i=0; i<8; ++i){
101 #if DEBUG
102                 cli_putstr("\r\nDBG: round ");
103                 cli_hexdump(&i, 1);
104                 cli_putstr(" buffer:");
105                 cli_hexdump(buffer, 8);
106 #endif
107                 for(j=0; j<3; ++j){
108                         if(j==0){
109                                 memxor(buffer, ctx->keys[i], 8);
110                         }else{
111                                 memxor(buffer, round_const+((j==1)?0:8), 8);
112                         }
113                         for(k=0; k<4; ++k){
114                                 ((uint16_t*)tmp)[k] = m(((uint16_t*)buffer)[k]);
115                         }
116                         for(k=0; k<4; ++k){
117                                 ((uint8_t*)buffer)[k]   = tmp[2*k];
118                                 ((uint8_t*)buffer)[k+4] = tmp[2*k+1];
119                         }
120                 }
121         }
122         memxor(buffer, ctx->keys[8], 8);
123 }
124
125 void cscipher_dec(void* buffer, const cscipher_ctx_t* ctx){
126         uint8_t i=7,j,k;
127         uint8_t tmp[8];
128         memxor(buffer, ctx->keys[8], 8);
129         do{
130                 for(j=0; j<3; ++j){
131                         for(k=0; k<4; ++k){
132                                 tmp[2*k]   = ((uint8_t*)buffer)[k];
133                                 tmp[2*k+1] = ((uint8_t*)buffer)[4+k];
134                         }
135                         for(k=0; k<4; ++k){
136                                 ((uint16_t*)buffer)[k] = m_inv(((uint16_t*)tmp)[k]);
137                         }
138                         if(j==2){
139                                 memxor(buffer, ctx->keys[i], 8);
140                         }else{
141                                 memxor(buffer, round_const+((j==1)?0:8), 8);
142                         }
143
144                 }
145         }while(i--);
146 }
147
148 void cscipher_init(const void* key, cscipher_ctx_t* ctx){
149         uint8_t tmp_key[16], tmp[8];
150         uint8_t i,j,k,t=0;
151         memcpy(tmp_key, key, 16);
152         for(i=0; i<9; ++i){
153 #if DEBUG
154                 cli_putstr("\r\nDBG: round ");
155                 cli_hexdump(&i, 1);
156                 cli_putstr(" key state:");
157                 cli_hexdump(tmp_key, 16);
158 #endif
159                 memcpy(tmp, tmp_key+(((i&1)==0)?0:8), 8);
160                 memxor(tmp, ks_const+8*i, 8);
161                 for(j=0; j<8; ++j){
162                         tmp[j] = P(tmp[j]);
163                 }
164                 for(j=0; j<8; ++j){
165                         for(k=0; k<8; ++k){
166                                 t<<=1;
167                                 t |= tmp[k]>>7;
168                                 tmp[k]<<=1;
169                         }
170                         tmp_key[j+(((i&1)==0)?8:0)] ^= t;
171                 }
172                 memcpy(ctx->keys[i], tmp_key+(((i&1)==0)?8:0), 8);
173         }
174 }