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64 lines
1.8 KiB
C
64 lines
1.8 KiB
C
/*
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* Blum, Blum & Shub PRNG using the MPI library
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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 "bbs_rand.h"
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#define SEED 1
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#define MODULUS 2
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/* This modulus is the product of two randomly generated 512-bit
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prime integers, each of which is congruent to 3 (mod 4). */
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static char *bbs_modulus =
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"75A2A6E1D27393B86562B9CE7279A8403CB4258A637DAB5233465373E37837383EDC"
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"332282B8575927BC4172CE8C147B4894050EE9D2BDEED355C121037270CA2570D127"
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"7D2390CD1002263326635CC6B259148DE3A1A03201980A925E395E646A5E9164B0EC"
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"28559EBA58C87447245ADD0651EDA507056A1129E3A3E16E903D64B437";
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static int bbs_init = 0; /* flag set when library is initialized */
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static mp_int bbs_state; /* the current state of the generator */
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/* Suggested size of random seed data */
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int bbs_seed_size = (sizeof(bbs_modulus) / 2);
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void bbs_srand(unsigned char *data, int len)
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{
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if((bbs_init & SEED) == 0) {
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mp_init(&bbs_state);
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bbs_init |= SEED;
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}
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mp_read_raw(&bbs_state, (char *)data, len);
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} /* end bbs_srand() */
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unsigned int bbs_rand(void)
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{
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static mp_int modulus;
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unsigned int result = 0, ix;
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if((bbs_init & MODULUS) == 0) {
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mp_init(&modulus);
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mp_read_radix(&modulus, bbs_modulus, 16);
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bbs_init |= MODULUS;
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}
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for(ix = 0; ix < sizeof(unsigned int); ix++) {
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mp_digit d;
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mp_sqrmod(&bbs_state, &modulus, &bbs_state);
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d = DIGIT(&bbs_state, 0);
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result = (result << CHAR_BIT) | (d & UCHAR_MAX);
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}
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return result;
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} /* end bbs_rand() */
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/*------------------------------------------------------------------------*/
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/* HERE THERE BE DRAGONS */
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