27 lines
812 B
C
27 lines
812 B
C
#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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void decrypt(uint32_t *v, uint32_t *k) {
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uint32_t v0 = v[0], v1 = v[1], sum = 0xC6EF3720, i; /* set up */
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uint32_t delta = 0x9e3779b9; /* a key schedule constant */
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uint32_t k0 = k[0], k1 = k[1], k2 = k[2], k3 = k[3]; /* cache key */
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for (i = 0; i < 32; i++) { /* basic cycle start */
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v1 -= ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3);
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v0 -= ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
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sum -= delta;
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} /* end cycle */
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v[0] = v0;
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v[1] = v1;
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}
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int main(int argc, char *argv[]) {
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if (argc != 3) {
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printf("Usage: %s text_to_decrypt key", argv[0]);
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exit(1);
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}
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decrypt((uint32_t*)argv[1], (uint32_t*)argv[2]);
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printf("Result: %s", argv[1]);
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return 0;
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} |