239 lines
5.1 KiB
C
239 lines
5.1 KiB
C
/* simple XXTEA en/decrypt utility
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*
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* BSD Licence
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*
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* btea function is from
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* <https://secure.wikimedia.org/wikipedia/en/wiki/XXTEA#Reference_code>
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*
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* (c) by Sec <sec@42.org> 6/2011
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*/
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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#include <getopt.h>
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// default block size
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void btea(uint32_t *v, int n, uint32_t const k[4]);
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void hexkey(char *string, uint32_t k[4]);
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int main(int argc, char *argv[]) {
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FILE *fp;
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FILE *ofp;
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char *prog;
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char c; /* for getopt */
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uint32_t k[4]; /* key */
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uint32_t *buf;
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/* Default values */
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char verbose=0; // be silent
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k[0]=0; k[1]=0; k[2]=0; k[3]=0;
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char block=16;
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char *outfile=NULL; // outfile == infile
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int decrypt=0;
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/* init section */
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prog=argv[0];
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if(!prog)prog="xxtea";
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if(strrchr(prog,'/')){
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prog=strrchr(argv[0],'/');
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prog++;
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}
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/* The big getopt loop */
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while ((c = getopt(argc, argv, "vhdk:b:o:")) != EOF)
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switch (c) {
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case 'v':
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verbose++;
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break;
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case 'd':
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decrypt=1;
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break;
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case 'k':
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hexkey(optarg, k);
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break;
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case 'b':
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block=atoi(optarg);
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break;
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case 'o':
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outfile=optarg;
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break;
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case 'h':
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default:
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fprintf(stderr, "Usage: %s [options] filename\n\n"
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"This program en/decrypts a file with the XXTEA algorithm\n"
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"\n\n"
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"-v Be verbose (-v -v = even more)\n"
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"-d Decrypt (instead of encrypt)\n"
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"-o file Output to <file>. (Default: overwrite input file)\n"
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"-k key 128bit hex key.\n"
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"-b block Set blocksize. (Default: file size)\n"
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"-h This help\n\n"
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"\n",prog);
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exit(255);
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}
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argc -= optind; argv += optind;
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if (argc !=1){
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fprintf(stderr,"Error: No filename given!\n");
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exit(254);
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};
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if(outfile){
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if ((fp = fopen(argv[0],"rb")) == NULL){
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fprintf(stderr,"Error: Can't open file %s\n",argv[0]);
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exit(253);
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}
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if ((ofp = fopen(outfile,"wb")) == NULL){
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fprintf(stderr,"Error: Can't open file %s\n",argv[0]);
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exit(253);
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}
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}else{
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if ((fp = fopen(argv[0],"r+b")) == NULL){
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fprintf(stderr,"Error: Can't open file %s\n",argv[0]);
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exit(253);
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}
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ofp=fp;
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};
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if(block==0){
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fseek(fp, 0L, SEEK_END);
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block = ftell(fp)/sizeof(*buf); // XXX: padding!
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fseek(fp, 0L, SEEK_SET);
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};
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buf=malloc(sizeof(*buf)*block);
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if(!buf){
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fprintf(stderr,"Error: malloc() failed.\n");
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};
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if (verbose)
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fprintf(stderr,"Key: %08x %08x %08x %08x\n",k[0],k[1],k[2],k[3]);
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int cnt;
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if (verbose)
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fprintf(stderr,"Encrypting: ");
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do{
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cnt=fread(buf,sizeof(*buf),block,fp); // XXX: deal with non-block-sized?
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if(cnt<0){
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fprintf(stderr, "Error: read failed\n");
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exit(253);
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};
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if(verbose)
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fprintf(stderr,"cnt=%d:",cnt);
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/* if(cnt%sizeof(*buf)!=0){
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fprintf(stderr,"Whoops. needs padding: cnt=%d, mod=%d\n",cnt,cnt%sizeof(*buf));
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}; */
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btea(buf, decrypt?-cnt:cnt, k);
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if(!outfile) // in-place crypting...
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if (fseek(fp,-cnt*sizeof(*buf),SEEK_CUR) != 0){
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fprintf(stderr, "Error: Seek failed\n");
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exit(253);
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}
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if (fwrite(buf,sizeof(*buf),cnt,ofp) != cnt){
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fprintf(stderr, "Error: CRC write failed\n");
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exit(253);
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}
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if(verbose) fprintf(stderr,".\n");
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}while(cnt==block);
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if(verbose)
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fprintf(stderr,"done\n");
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fclose(fp);
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if(outfile)
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fclose(ofp);
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return 0;
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}
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#define DELTA 0x9e3779b9
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#define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (k[(p&3)^e] ^ z)))
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void btea(uint32_t *v, int n, uint32_t const k[4]) {
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uint32_t y, z, sum;
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unsigned p, rounds, e;
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if (n > 1) { /* Coding Part */
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rounds = 6 + 52/n;
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sum = 0;
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z = v[n-1];
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do {
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sum += DELTA;
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e = (sum >> 2) & 3;
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for (p=0; p<n-1; p++) {
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y = v[p+1];
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z = v[p] += MX;
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}
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y = v[0];
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z = v[n-1] += MX;
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} while (--rounds);
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} else if (n < -1) { /* Decoding Part */
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n = -n;
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rounds = 6 + 52/n;
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sum = rounds*DELTA;
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y = v[0];
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do {
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e = (sum >> 2) & 3;
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for (p=n-1; p>0; p--) {
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z = v[p-1];
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y = v[p] -= MX;
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}
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z = v[n-1];
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y = v[0] -= MX;
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} while ((sum -= DELTA) != 0);
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}
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}
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void hexkey(char *string, uint32_t k[4]){
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int idx=0;
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int kidx=0;
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int kctr=0;
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int value;
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char ch;
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while ((ch=string[idx++])!=0){
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if(ch == ' ')
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continue;
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if(ch == '\t')
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continue;
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if (ch >= '0' && ch <= '9')
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value = (ch - '0');
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else if (ch >= 'A' && ch <= 'F')
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value = (ch - 'A' + 10);
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else if (ch >= 'a' && ch <= 'f')
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value = (ch - 'a' + 10);
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else
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continue;
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k[kidx]=(k[kidx]<<4)+value;
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kctr++;
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if(kctr>=8){
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kctr=0;
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kidx++;
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if(kidx>4)
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return;
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};
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};
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}
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