crashtest-r0ket/tools/crypto/xxtea.c

195 lines
4.2 KiB
C

/* simple XXTEA en/decrypt utility
*
* BSD Licence
*
* btea function is from
* <https://secure.wikimedia.org/wikipedia/en/wiki/XXTEA#Reference_code>
*
* (c) by Sec <sec@42.org> 6/2011
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <getopt.h>
// default block size
void btea(uint32_t *v, int n, uint32_t const k[4]);
int main(int argc, char *argv[]) {
FILE *fp;
FILE *ofp;
char *prog;
char c; /* for getopt */
uint32_t k[4]; /* key */
uint32_t *buf;
/* Default values */
char verbose=0; // be silent
k[0]=0; k[1]=0; k[2]=0; k[3]=0;
char block=16;
char *outfile=NULL; // outfile == infile
/* init section */
prog=argv[0];
if(!prog)prog="xxtea";
if(strrchr(prog,'/')){
prog=strrchr(argv[0],'/');
prog++;
}
/* The big getopt loop */
while ((c = getopt(argc, argv, "vhk:b:o:")) != EOF)
switch (c) {
case 'v':
verbose++;
break;
case 'k':
// XXX: get key
break;
case 'b':
block=atoi(optarg);
break;
case 'o':
outfile=optarg;
break;
case 'h':
default:
fprintf(stderr, "Usage: %s [options] filename\n\n"
"This program en/decrypts a file with the XXTEA algorithm\n"
"\n\n"
"-v Be verbose (-v -v = even more)\n"
"-o file Output to <file>. (Default: overwrite input file)\n"
"-k key 128bit hex key. [Not yet implemented]\n"
"-b block Set blocksize. (Default: file size)\n"
"-h This help\n\n"
"\n",prog);
exit(255);
}
argc -= optind; argv += optind;
if (argc !=1){
fprintf(stderr,"Error: No filename given!\n");
exit(254);
};
if(outfile){
if ((fp = fopen(argv[0],"rb")) == NULL){
fprintf(stderr,"Error: Can't open file %s\n",argv[0]);
exit(253);
}
if ((ofp = fopen(outfile,"wb")) == NULL){
fprintf(stderr,"Error: Can't open file %s\n",argv[0]);
exit(253);
}
}else{
if ((fp = fopen(argv[0],"r+b")) == NULL){
fprintf(stderr,"Error: Can't open file %s\n",argv[0]);
exit(253);
}
ofp=fp;
};
if(block==0){
fseek(fp, 0L, SEEK_END);
block = ftell(fp)/sizeof(*buf); // XXX: padding!
fseek(fp, 0L, SEEK_SET);
};
buf=malloc(sizeof(*buf)*block);
if(!buf){
fprintf(stderr,"Error: malloc() failed.\n");
};
int cnt;
if (verbose)
fprintf(stderr,"Encrypting: ");
do{
cnt=fread(buf,sizeof(*buf),block,fp); // XXX: deal with non-block-sized?
if(cnt<0){
fprintf(stderr, "Error: read failed\n");
exit(253);
};
if(verbose)
fprintf(stderr,"cnt=%d:",cnt);
/* if(cnt%sizeof(*buf)!=0){
fprintf(stderr,"Whoops. needs padding: cnt=%d, mod=%d\n",cnt,cnt%sizeof(*buf));
}; */
btea(buf, cnt, k);
if(!outfile) // in-place crypting...
if (fseek(fp,-cnt*sizeof(*buf),SEEK_CUR) != 0){
fprintf(stderr, "Error: Seek failed\n");
exit(253);
}
if (fwrite(buf,sizeof(*buf),cnt,ofp) != cnt){
fprintf(stderr, "Error: CRC write failed\n");
exit(253);
}
if(verbose) fprintf(stderr,".\n");
}while(cnt==block);
if(verbose)
fprintf(stderr,"done\n");
fclose(fp);
if(outfile)
fclose(ofp);
return 0;
}
#define DELTA 0x9e3779b9
#define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (k[(p&3)^e] ^ z)))
void btea(uint32_t *v, int n, uint32_t const k[4]) {
uint32_t y, z, sum;
unsigned p, rounds, e;
if (n > 1) { /* Coding Part */
rounds = 6 + 52/n;
sum = 0;
z = v[n-1];
do {
sum += DELTA;
e = (sum >> 2) & 3;
for (p=0; p<n-1; p++) {
y = v[p+1];
z = v[p] += MX;
}
y = v[0];
z = v[n-1] += MX;
} while (--rounds);
} else if (n < -1) { /* Decoding Part */
n = -n;
rounds = 6 + 52/n;
sum = rounds*DELTA;
y = v[0];
do {
e = (sum >> 2) & 3;
for (p=n-1; p>0; p--) {
z = v[p-1];
y = v[p] -= MX;
}
z = v[n-1];
y = v[0] -= MX;
} while ((sum -= DELTA) != 0);
}
}