idcrypt.c

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/*****************************************************************************/
#include "libtpcmisc.h"
/*****************************************************************************/
 
/*****************************************************************************/
 
const char *libpet_idcrypt_version(void) {
    return "2004-12-14";
}
 
int id_crypt(
  const char *string,
  const char *key,
  char *out,
  int decrypt
) {
    char *keystr;
    unsigned int len, r;
 
    len=strlen(string);
    if(len==0) return 0;
 
    keystr = malloc(len);
    if(!keystr) return 1;
 
    if(len>strlen(key)) {
        for(r=0;r<len;r++) {
            keystr[r]=key[r%strlen(key)]-32;
            if(keystr[r]>94) keystr[r]=94;
        }
    } else {
        for(r=0;r<len;r++) {
            keystr[r]=key[r]-32;
            if(keystr[r]>94) keystr[r]=94;
        }
    }
 
    for(r=0;r<len;r++) {
        int c=(unsigned char)string[r]-32;
        if(c>94) c=94;
        if(decrypt) {
            c=c-keystr[r];
            if(c<0) c=(95-(-c)%95);
        } else {
            c=(c+keystr[r])%95;
        }
        out[r]=c+32;
    }
    out[r]=0;
    free(keystr);
    return 0;
}