344 lines
8.4 KiB
C
344 lines
8.4 KiB
C
/* serpent.c
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* a bitsliced implementation of the serpent cipher for avr microcontrollers
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* author: Daniel Otte
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* license: GPLv3
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*/
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#include <stdint.h>
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#include <string.h> /* memset() */
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#include <avr/pgmspace.h>
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#include "uart.h"
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#include "debug.h"
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/*
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S0: 3 8 15 1 10 6 5 11 14 13 4 2 7 0 9 12
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S1: 15 12 2 7 9 0 5 10 1 11 14 8 6 13 3 4
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S2: 8 6 7 9 3 12 10 15 13 1 14 4 0 11 5 2
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S3: 0 15 11 8 12 9 6 3 13 1 2 4 10 7 5 14
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S4: 1 15 8 3 12 0 11 6 2 5 4 10 9 14 7 13
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S5: 15 5 2 11 4 10 9 12 0 3 14 8 13 6 7 1
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S6: 7 2 12 5 8 4 6 11 14 9 1 15 13 3 10 0
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S7: 1 13 15 0 14 8 2 11 7 4 12 10 9 3 5 6
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*/
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uint8_t sbox[] PROGMEM = {
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0x38, 0xF1, 0xA6, 0x5B, 0xED, 0x42, 0x70, 0x9C,
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0xFC, 0x27, 0x90, 0x5A, 0x1B, 0xE8, 0x6D, 0x34,
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0x86, 0x79, 0x3C, 0xAF, 0xD1, 0xE4, 0x0B, 0x52,
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0x0F, 0xB8, 0xC9, 0x63, 0xD1, 0x24, 0xA7, 0x5E,
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0x1F, 0x83, 0xC0, 0xB6, 0x25, 0x4A, 0x9E, 0x7D,
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0xF5, 0x2B, 0x4A, 0x9C, 0x03, 0xE8, 0xD6, 0x71,
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0x72, 0xC5, 0x84, 0x6B, 0xE9, 0x1F, 0xD3, 0xA0,
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0x1D, 0xF0, 0xE8, 0x2B, 0x74, 0xCA, 0x93, 0x56,
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/* now the inverted sboxes */
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0xD3, 0xB0, 0xA6, 0x5C, 0x1E, 0x47, 0xF9, 0x82,
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0x58, 0x2E, 0xF6, 0xC3, 0xB4, 0x79, 0x1D, 0xA0,
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0xC9, 0xF4, 0xBE, 0x12, 0x03, 0x6D, 0x58, 0xA7,
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0x09, 0xA7, 0xBE, 0x6D, 0x35, 0xC2, 0x48, 0xF1,
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0x50, 0x83, 0xA9, 0x7E, 0x2C, 0xB6, 0x4F, 0xD1,
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0x8F, 0x29, 0x41, 0xDE, 0xB6, 0x53, 0x7C, 0xA0,
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0xFA, 0x1D, 0x53, 0x60, 0x49, 0xE7, 0x2C, 0x8B,
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0x30, 0x6D, 0x9E, 0xF8, 0x5C, 0xB7, 0xA1, 0x42
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};
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/*
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InvS0: 13 3 11 0 10 6 5 12 1 14 4 7 15 9 8 2
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InvS1: 5 8 2 14 15 6 12 3 11 4 7 9 1 13 10 0
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InvS2: 12 9 15 4 11 14 1 2 0 3 6 13 5 8 10 7
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InvS3: 0 9 10 7 11 14 6 13 3 5 12 2 4 8 15 1
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InvS4: 5 0 8 3 10 9 7 14 2 12 11 6 4 15 13 1
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InvS5: 8 15 2 9 4 1 13 14 11 6 5 3 7 12 10 0
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InvS6: 15 10 1 13 5 3 6 0 4 9 14 7 2 12 8 11
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InvS7: 3 0 6 13 9 14 15 8 5 12 11 7 10 1 4 2
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*/
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/*
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uint8_t invsbox[] PROGMEM = {
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0xD3, 0xB0, 0xA6, 0x5C, 0x1E, 0x47, 0xF9, 0x82,
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0x58, 0x2E, 0xF6, 0xC3, 0xB4, 0x79, 0x1D, 0xA0,
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0xC9, 0xF4, 0xBE, 0x12, 0x03, 0x6D, 0x58, 0xA7,
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0x09, 0xA7, 0xBE, 0x6D, 0x35, 0xC2, 0x48, 0xF1,
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0x50, 0x83, 0xA9, 0x7E, 0x2C, 0xB6, 0x4F, 0xD1,
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0x8F, 0x29, 0x41, 0xDE, 0xB6, 0x53, 0x7C, 0xA0,
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0xFA, 0x1D, 0x53, 0x60, 0x49, 0xE7, 0x2C, 0x8B,
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0x30, 0x6D, 0x9E, 0xF8, 0x5C, 0xB7, 0xA1, 0x42
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}
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*/
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static uint8_t byteflip(uint8_t v){
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uint8_t tab[] = { 0x0, 0x8, 0x4, 0xC,
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0x2, 0xA, 0x6, 0xE,
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0x1, 0x9, 0x5, 0xD,
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0x3, 0xB, 0x7, 0xF };
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uint8_t ret;
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ret = ((tab[v&0xf]) << 4) | tab[v>>4];
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return ret;
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}
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static uint8_t getbit(void* b, uint8_t addr){
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uint8_t t;
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t = ((uint8_t*)b)[addr/8];
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t = (t&(1<<(addr&0x7)))?1:0;
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return t;
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}
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static void setbit(void* b, uint8_t addr, uint8_t v){
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uint8_t t;
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t = ((uint8_t*)b)[addr/8];
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if(v){
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t |= 1<<(addr&0x7);
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} else {
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t &= ~(1<<(addr&0x7));
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}
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((uint8_t*)b)[addr/8] = t;
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}
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/*
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uint8_t ip_table[] PROGMEM = {
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0, 32, 64, 96, 1, 33, 65, 97, 2, 34, 66, 98, 3, 35, 67, 99,
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4, 36, 68, 100, 5, 37, 69, 101, 6, 38, 70, 102, 7, 39, 71, 103,
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8, 40, 72, 104, 9, 41, 73, 105, 10, 42, 74, 106, 11, 43, 75, 107,
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12, 44, 76, 108, 13, 45, 77, 109, 14, 46, 78, 110, 15, 47, 79, 111,
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16, 48, 80, 112, 17, 49, 81, 113, 18, 50, 82, 114, 19, 51, 83, 115,
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20, 52, 84, 116, 21, 53, 85, 117, 22, 54, 86, 118, 23, 55, 87, 119,
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24, 56, 88, 120, 25, 57, 89, 121, 26, 58, 90, 122, 27, 59, 91, 123,
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28, 60, 92, 124, 29, 61, 93, 125, 30, 62, 94, 126, 31, 63, 95, 127
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};
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* /
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uint8_t fp_table[] PROGMEM = {
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0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60,
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64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124,
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1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61,
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65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125,
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2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62,
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66, 70, 74, 78, 82, 86, 90, 94, 98, 102, 106, 110, 114, 118, 122, 126,
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3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63,
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67, 71, 75, 79, 83, 87, 91, 95, 99, 103, 107, 111, 115, 119, 123, 127
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};
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*/
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/*
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static void ip_stupid(void* out, void* in){
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uint8_t i,x,t;
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for(i=0; i<128; ++i){
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t = pgm_read_byte(ip_table + i);
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x = getbit(in, t);
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setbit(out, i, x);
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}
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}
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*/
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/*
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static void fp_stupid(void* out, void* in){
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uint8_t i,x,t;
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for(i=0; i<128; ++i){
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t = pgm_read_byte(fp_table + i);
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x = getbit(in, t);
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setbit(out, i, x);
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}
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}
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*/
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/* this is a implementation of the needed propertys only! */
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#define SHR_O(a) c=(a)&1; ((a) = (a)>>1)
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#define SHR_I(a) ((a) = (c?0x80:0x00)| ((a)>>1))
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static void ip(uint8_t *o, uint32_t *i){
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uint8_t c; // carry
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uint8_t n,m;
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memset(o, 0, 16);
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for(n=0; n<16; ++n){
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for(m=0; m<2; ++m){
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SHR_O(i[0]);
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SHR_I(o[n]);
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SHR_O(i[1]);
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SHR_I(o[n]);
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SHR_O(i[2]);
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SHR_I(o[n]);
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SHR_O(i[3]);
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SHR_I(o[n]);
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}
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}
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}
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#undef SHR_I
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#define SHR_I(a) ((a) = (c?0x80000000L:0x00L)| ((a)>>1)) /* we use 32-bit words here */
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static void fp(uint32_t *o, uint32_t *i){
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uint8_t c; // carry
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uint8_t n,m;
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memset(o, 0, 16);
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for(n=0; n<4; ++n){
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for(m=0; m<8; ++m){
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SHR_O(i[n]);
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SHR_I(o[0]);
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SHR_O(i[n]);
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SHR_I(o[1]);
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SHR_O(i[n]);
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SHR_I(o[2]);
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SHR_O(i[n]);
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SHR_I(o[3]);
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}
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}
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}
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/******************************************************************************/
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static void sbox128x(uint8_t box, void* w){
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uint8_t sb[16];
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uint8_t i,t,x;
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box &= 0x0f;
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/* load sbox */
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for(i=0; i<8; ++i){
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t = pgm_read_byte(sbox + box*8 + i);
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sb[2*i+0]=t>>4;
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sb[2*i+1]=t&0xf;
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}
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uint8_t o[16];
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ip(o, w);
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for(i=0; i<16; ++i){
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t = ((uint8_t*)o)[i];
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x = sb[t>>4];
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x <<= 4;
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x |= sb[t&0xf];
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((uint8_t*)o)[i] = x;
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}
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fp(w, o);
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}
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static void sbox128(void * w, uint8_t box){
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sbox128x(box&0x7, w);
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}
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static void inv_sbox128(void * w, uint8_t box){
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sbox128x(((box&0x7)|0x8), w);
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}
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/******************************************************************************/
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void memxor(void * dest, void * src, uint8_t size){
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while(size--){
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*((uint8_t*)dest) ^= *((uint8_t*)src);
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dest = (uint8_t*)dest +1;
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src = (uint8_t*)src +1;
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}
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}
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/******************************************************************************/
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uint32_t rotl32(uint32_t a, uint8_t n){
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return ((a<<n) | (a>>(32-n)));
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}
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uint32_t rotr32(uint32_t a, uint8_t n){
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return ((a>>n) | (a<<(32-n)));
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}
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#define X0 (((uint32_t*)b)[0])
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#define X1 (((uint32_t*)b)[1])
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#define X2 (((uint32_t*)b)[2])
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#define X3 (((uint32_t*)b)[3])
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static void lt(uint8_t *b){
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X0 = rotl32(X0, 13);
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X2 = rotl32(X2, 3);
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X1 ^= X0 ^ X2;
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X3 ^= X2 ^ (X0 << 3);
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X1 = rotl32(X1, 1);
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X3 = rotl32(X3, 7);
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X0 ^= X1 ^ X3;
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X2 ^= X3 ^ (X1 << 7);
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X0 = rotl32(X0, 5);
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X2 = rotr32(X2, 10);
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}
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static void inv_lt(uint8_t *b){
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X2 = rotl32(X2, 10);
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X0 = rotr32(X0, 5);
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X2 ^= X3 ^ (X1 << 7);
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X0 ^= X1 ^ X3;
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X3 = rotr32(X3, 7);
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X1 = rotr32(X1, 1);
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X3 ^= X2 ^ (X0 << 3);
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X1 ^= X0 ^ X2;
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X2 = rotr32(X2, 3);
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X0 = rotr32(X0, 13);
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}
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typedef uint32_t serpent_subkey_t[4];
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typedef struct serpent_ctx_st {
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serpent_subkey_t k[33];
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} serpent_ctx_t;
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#define GOLDEN_RATIO 0x9e3779b9l
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static uint32_t gen_w(uint32_t * b, uint8_t i){
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uint32_t ret;
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ret = b[0] ^ b[3] ^ b[5] ^ b[7] ^ GOLDEN_RATIO ^ (uint32_t)i;
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ret = rotl32(ret, 11);
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return ret;
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}
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/* key must be 256bit (32 byte) large! */
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void serpent_genctx(void * key, serpent_ctx_t * ctx){
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uint32_t buffer[8];
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uint8_t i,j;
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memcpy(buffer, key, 32);
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for(i=0; i<33; ++i){
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for(j=0; j<4; ++j){
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ctx->k[i][j] = gen_w(buffer, i*4+j);
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memmove(buffer, &(buffer[1]), 7*4); /* shift buffer one to the "left" */
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buffer[7] = ctx->k[i][j];
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/*
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uart_putstr("\r\n w[");
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uart_putc('0'+(4*i+j)/100);
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uart_putc('0'+((4*i+j)/10)%10);
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uart_putc('0'+(4*i+j)%10);
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uart_putstr("] = ");
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uart_hexdump(&(ctx->k[i][j]), 4);
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*/
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}
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}
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for(i=0; i<33; ++i){
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sbox128(ctx->k[i],3-i);
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}
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}
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void serpent_enc(void* buffer, serpent_ctx_t * ctx){
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uint8_t i;
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for(i=0; i<31; ++i){
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memxor((uint8_t*)buffer, ctx->k[i], 16);
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sbox128(buffer, i);
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lt((uint8_t*)buffer);
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}
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memxor((uint8_t*)buffer, ctx->k[i], 16);
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sbox128(buffer, i);
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++i;
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memxor((uint8_t*)buffer, ctx->k[i], 16);
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}
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void serpent_dec(void* buffer, serpent_ctx_t * ctx){
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int8_t i=32;
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memxor((uint8_t*)buffer, ctx->k[i], 16);
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--i;
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inv_sbox128(buffer, i);
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memxor((uint8_t*)buffer, ctx->k[i], 16);
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--i;
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for(; i>=0; --i){
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inv_lt((uint8_t*)buffer);
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inv_sbox128(buffer, i);
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memxor((uint8_t*)buffer, ctx->k[i], 16);
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}
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}
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