]> git.cryptolib.org Git - avr-crypto-lib.git/blob - present.c
bug fixed in md5-asm.S ( wrong values for length_b%512=505..511 )
[avr-crypto-lib.git] / present.c
1 /* present.c */
2 /*
3     This file is part of the AVR-Crypto-Lib.
4     Copyright (C) 2008  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  * present.c
21  * a implementation of the PRESENT block-cipher
22  * author: Daniel Otte
23  * email:  daniel.otte@rub.de
24  * license: GPLv3
25  * 
26  * */
27  
28 #include <string.h>
29 #include <stdint.h> 
30 #include "present.h"
31
32 static uint8_t sbox(uint8_t b){
33         uint8_t sb[]={0xC, 0x5, 0x6, 0xB, 
34                                   0x9, 0x0, 0xA, 0xD, 
35                                   0x3, 0xE, 0xF, 0x8, 
36                                   0x4, 0x7, 0x1, 0x2 };
37         return (((sb[b>>4])<<4)|(sb[b&0xf]));
38 }
39
40 static uint8_t sbox_inv(uint8_t b){
41         uint8_t sb[]={0x5, 0xE, 0xF, 0x8, 
42                                   0xC, 0x1, 0x2, 0xD, 
43                                   0xB, 0x4, 0x6, 0x3, 
44                                   0x0, 0x7, 0x9, 0xA };
45         return (((sb[b>>4])<<4)|(sb[b&0xf]));
46 }
47
48 #define SHR_O(a) c=(a)&1; (a)>>=1;
49 #define SHR_I(a) (a)=(c?0x8000:0x0000) | ((a)>>1);
50
51 static void p(uint16_t* o, uint8_t* i){
52         uint8_t c;
53         uint8_t m,n;
54         for(m=0; m<8; ++m){
55                 for(n=0; n<2; ++n){
56                         SHR_O(i[m]);
57                         SHR_I(o[0]);
58                         SHR_O(i[m]);
59                         SHR_I(o[1]);
60                         SHR_O(i[m]);
61                         SHR_I(o[2]);
62                         SHR_O(i[m]);
63                         SHR_I(o[3]);
64                 }
65         }
66 }
67
68 static void p_inv(uint8_t* o, uint8_t* i){
69         uint8_t tmp[8];
70         p((uint16_t*)tmp, i);
71         p((uint16_t*)o, tmp);
72 }
73
74 void present_init(const uint8_t* key, uint8_t keysize_b, present_ctx_t* ctx){
75         uint8_t buffer[10], tmp[2];
76         uint8_t i;
77         memcpy(buffer, key, 10);
78         memcpy(&(ctx->k[0]), buffer+2, 8);
79         for(i=1; i<32; ++i){
80                 /* rotate buffer 19 right */
81                 memcpy(tmp, buffer, 2);
82                 memmove(buffer, buffer+2, 8);
83                 memcpy(buffer+8, tmp, 2);
84                  /* three shifts to do*/
85                 tmp[1]=buffer[0];
86                 *((uint64_t*)buffer)>>=3;
87                 *((uint16_t*)(buffer+8))>>=3;
88                 buffer[9] |= tmp[1]<<5;
89                 buffer[7] |= tmp[0]<<5;
90                 /* rotating done now substitution */
91                 buffer[9] = (sbox(buffer[9])&0xF0) | ((buffer[9])&0x0F);
92                 /* xor with round counter */
93                 *((uint16_t*)(buffer+1)) ^= (uint16_t)i<<7;
94                 memcpy(&(ctx->k[i]), buffer+2, 8);
95         }
96 }
97
98 void present_enc(void* buffer, present_ctx_t* ctx){
99         uint8_t i,j,tmp[8];
100         for(i=0; i<31; ++i){
101                 *((uint64_t*)buffer) ^= ctx->k[i];
102                  for(j=0; j<8; ++j){
103                         tmp[j] = sbox(((uint8_t*)buffer)[j]);
104                  }
105                  p((uint16_t*)buffer, tmp);
106         }
107         *((uint64_t*)buffer) ^= ctx->k[31];
108 }
109
110
111 void present_dec(void* buffer, present_ctx_t* ctx){
112         uint8_t j,tmp[8];
113         int8_t i;
114         *((uint64_t*)buffer) ^= ctx->k[31];
115
116         for(i=30; i>=0; --i){ 
117                 p_inv(tmp, (uint8_t*)buffer);
118                 for(j=0; j<8; ++j){
119                         ((uint8_t*)buffer)[j] = sbox_inv(tmp[j]);
120                 }
121                 *((uint64_t*)buffer) ^= ctx->k[i];
122         }
123 }