125 lines
3.2 KiB
C
125 lines
3.2 KiB
C
/* Portable C code to create DES key schedules from user-provided keys
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* This doesn't have to be fast unless you're cracking keys or UNIX
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* passwords
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*/
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#include <string.h>
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#include "des.h"
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/* Key schedule-related tables from FIPS-46 */
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/* permuted choice table (key) */
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static unsigned char pc1[] = {
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57, 49, 41, 33, 25, 17, 9,
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1, 58, 50, 42, 34, 26, 18,
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10, 2, 59, 51, 43, 35, 27,
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19, 11, 3, 60, 52, 44, 36,
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63, 55, 47, 39, 31, 23, 15,
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7, 62, 54, 46, 38, 30, 22,
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14, 6, 61, 53, 45, 37, 29,
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21, 13, 5, 28, 20, 12, 4
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};
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/* number left rotations of pc1 */
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static unsigned char totrot[] = {
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1,2,4,6,8,10,12,14,15,17,19,21,23,25,27,28
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};
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/* permuted choice key (table) */
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static unsigned char pc2[] = {
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14, 17, 11, 24, 1, 5,
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3, 28, 15, 6, 21, 10,
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23, 19, 12, 4, 26, 8,
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16, 7, 27, 20, 13, 2,
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41, 52, 31, 37, 47, 55,
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30, 40, 51, 45, 33, 48,
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44, 49, 39, 56, 34, 53,
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46, 42, 50, 36, 29, 32
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};
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/* End of DES-defined tables */
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/* bit 0 is left-most in byte */
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static int bytebit[] = {
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0200,0100,040,020,010,04,02,01
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};
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/* Generate key schedule for encryption or decryption
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* depending on the value of "decrypt"
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*/
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void
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deskey(DES_KS k,unsigned char *key,int decrypt)
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/* Key schedule array */
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/* 64 bits (will use only 56) */
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/* 0 = encrypt, 1 = decrypt */
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{
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unsigned char pc1m[56]; /* place to modify pc1 into */
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unsigned char pcr[56]; /* place to rotate pc1 into */
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register int i,j,l;
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int m;
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unsigned char ks[8];
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for (j=0; j<56; j++) { /* convert pc1 to bits of key */
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l=pc1[j]-1; /* integer bit location */
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m = l & 07; /* find bit */
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pc1m[j]=(key[l>>3] & /* find which key byte l is in */
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bytebit[m]) /* and which bit of that byte */
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? 1 : 0; /* and store 1-bit result */
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}
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for (i=0; i<16; i++) { /* key chunk for each iteration */
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memset(ks,0,sizeof(ks)); /* Clear key schedule */
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for (j=0; j<56; j++) /* rotate pc1 the right amount */
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pcr[j] = pc1m[(l=j+totrot[decrypt? 15-i : i])<(j<28? 28 : 56) ? l: l-28];
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/* rotate left and right halves independently */
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for (j=0; j<48; j++){ /* select bits individually */
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/* check bit that goes to ks[j] */
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if (pcr[pc2[j]-1]){
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/* mask it in if it's there */
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l= j % 6;
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ks[j/6] |= bytebit[l] >> 2;
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}
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}
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/* Now convert to packed odd/even interleaved form */
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k[i][0] = ((long)ks[0] << 24)
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| ((long)ks[2] << 16)
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| ((long)ks[4] << 8)
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| ((long)ks[6]);
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k[i][1] = ((long)ks[1] << 24)
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| ((long)ks[3] << 16)
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| ((long)ks[5] << 8)
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| ((long)ks[7]);
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if(Asmversion){
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/* The assembler versions pre-shift each subkey 2 bits
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* so the Spbox indexes are already computed
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*/
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k[i][0] <<= 2;
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k[i][1] <<= 2;
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}
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}
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}
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/* Generate key schedule for triple DES in E-D-E (or D-E-D) mode.
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*
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* The key argument is taken to be 24 bytes. The first 8 bytes are K1
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* for the first stage, the second 8 bytes are K2 for the middle stage
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* and the third 8 bytes are K3 for the last stage
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*/
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void
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des3key(DES3_KS k,unsigned char *key,int decrypt)
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/* 192 bits (will use only 168) */
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/* 0 = encrypt, 1 = decrypt */
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{
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if(!decrypt){
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deskey(&k[0],&key[0],0);
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deskey(&k[16],&key[8],1);
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deskey(&k[32],&key[16],0);
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} else {
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deskey(&k[32],&key[0],1);
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deskey(&k[16],&key[8],0);
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deskey(&k[0],&key[16],1);
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}
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}
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