37 lines
658 B
C
37 lines
658 B
C
#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#define RAND_MAX ((1U << 31) - 1)
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#define MAXLENGTH 80
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int realrand() {
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int n;
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FILE *fp = fopen("/dev/urandom", "r");
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fread(&n, 4, 1, fp);
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fclose(fp);
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return n % MAXLENGTH;
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}
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int seed;
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int pseudorand() {
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return seed = (seed * 19394489 + 132241) & 0xff;
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}
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int main() {
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char input[MAXLENGTH];
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FILE *fp = fopen("flag.in", "r");
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fread(&input, 1, MAXLENGTH, fp);
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fclose(fp);
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fp = fopen("flag.out", "wb");
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seed = realrand();
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int r;
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char c;
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for (int i = 0, l = strlen(input); i < l; ++i) {
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c = ((char) input[i] ^ (r = pseudorand())) & 0xff;
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fwrite(&c, 1, 1, fp);
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}
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fclose(fp);
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}
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