Problem - Kevin Tafuro

* typedefs for clarity */
typedef unsigned char obit_t;
typedef struct obyte obyte_t;
typedef struct obint obint_t;
int obytes_equal(obyte_t *a, obyt_t *b) {
int i;
for (i = 0; i < 8; i++)
if (obit_get(a.s[i]) != obit_get(b.s[i])) return 0;
return 1;
}
/* do-nothing subroutines */
void action_write(char *arg) { printf("write %s\n", arg); }
void action_read(char *arg) { printf("read %s\n", arg); }
void action_error(void) { printf("ERROR: Bad parameter\n"); }{
int main(int argc, char *argv[ ]) {
obyte_t input, read_val, write_val;
unsigned char i;
if (argc < 2) {
fprintf(stderr, "Usage: %s num string\n", argv[0]);
return 1;
}
/* initialize the obcode lib with a random key */
obcode_init(0);
/* obfuscate the first argument */
obyte_set(&input, (unsigned char)atoi(argv[1]));
/* obfuscate the values to compare it to--these should really be stored in
* obfuscated form instead of generated
*/
obyte_set(&read_val, 63);
obyte_set(&write_val, 112);
/* perform comparisons */
if (obytes_equal(&input, &read_val)) action_read(argv[2]);
else if (obytes_equal(&input, &write_val)) action_write(argv[2]);
else action_err( );
/* cleanup */
obcode_finish( );
return 0;
}
See Also
Obcode library by Pawel Krawczyk: http://echelon.pl/pubs/
666 | Chapter 12: Anti-Tampering
This is the Title of the Book, eMatter Edition
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