gipu/polictf/tea_cversion/tea-decrypt.c

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#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
void decrypt(uint16_t *v) {
uint16_t v0 = v[0], v1 = v[1], sum = 0x3780, i; /* set up */
uint16_t delta = 0x626f; /* a key schedule constant */
uint16_t k0 = 0x7065; // "pe"
uint16_t k1 = 0x7065; // "pe"
uint16_t k2 = 0x7275; // "ru"
uint16_t k3 = 0x6e73; // "ns"
for (i = 0; i < 128; i++) {
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//printf("Intermediate v0: 0x%x | v1: 0x%x\n", v0, v1); /* basic cycle
// start */
v1 -= ((v0 << 4) + k2) ^ (v0) ^ ((v0 >> 5) + k3);
v0 -= ((v1 << 4) + k0) ^ (v1) ^ ((v1 >> 5) + k1);
sum -= delta;
} /* end cycle */
v[0] = v0;
v[1] = v1;
}
int main(int argc, char *argv[]) {
uint8_t buf[1000];
uint32_t buflen, i;
fprintf(stdout, "Length of the string?\n");
fflush(stdout);
fscanf(stdin, "%d", &buflen);
printf("Length: %d\n", buflen);
read(0, buf, buflen);
for (i = 0; i < buflen && i + 2 * (sizeof(uint16_t)) <= buflen;
i += sizeof(uint32_t)) {
decrypt((uint16_t *)&buf[i]);
}
for (i = 0; i < buflen; i++) {
fprintf(stdout, "buf[%d] = 0x%02x\n", i, buf[i]);
}
printf("STRING: %s\n", buf);
fflush(stdout);
}