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51 lines
1.1 KiB
C
51 lines
1.1 KiB
C
/*
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* exptmod.c
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*
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* Command line tool to perform modular exponentiation on arbitrary
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* precision integers.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "mpi.h"
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int main(int argc, char *argv[])
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{
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mp_int a, b, m;
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mp_err res;
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char *str;
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int len, rval = 0;
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if(argc < 3) {
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fprintf(stderr, "Usage: %s <a> <b> <m>\n", argv[0]);
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return 1;
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}
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mp_init(&a); mp_init(&b); mp_init(&m);
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mp_read_radix(&a, argv[1], 10);
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mp_read_radix(&b, argv[2], 10);
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mp_read_radix(&m, argv[3], 10);
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if((res = mp_exptmod(&a, &b, &m, &a)) != MP_OKAY) {
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fprintf(stderr, "%s: error: %s\n", argv[0], mp_strerror(res));
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rval = 1;
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} else {
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len = mp_radix_size(&a, 10);
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str = calloc(len, sizeof(char));
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mp_toradix(&a, str, 10);
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printf("%s\n", str);
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free(str);
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}
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mp_clear(&a); mp_clear(&b); mp_clear(&m);
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return rval;
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}
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