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lightning-sunbird  0.9+nobinonly
bbs_rand.c
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00001 /*
00002  *  Blum, Blum & Shub PRNG using the MPI library
00003  *
00004  * ***** BEGIN LICENSE BLOCK *****
00005  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
00006  *
00007  * The contents of this file are subject to the Mozilla Public License Version
00008  * 1.1 (the "License"); you may not use this file except in compliance with
00009  * the License. You may obtain a copy of the License at
00010  * http://www.mozilla.org/MPL/
00011  *
00012  * Software distributed under the License is distributed on an "AS IS" basis,
00013  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
00014  * for the specific language governing rights and limitations under the
00015  * License.
00016  *
00017  * The Original Code is the MPI Arbitrary Precision Integer Arithmetic library.
00018  *
00019  * The Initial Developer of the Original Code is
00020  * Michael J. Fromberger.
00021  * Portions created by the Initial Developer are Copyright (C) 1998
00022  * the Initial Developer. All Rights Reserved.
00023  *
00024  * Contributor(s):
00025  *
00026  * Alternatively, the contents of this file may be used under the terms of
00027  * either the GNU General Public License Version 2 or later (the "GPL"), or
00028  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
00029  * in which case the provisions of the GPL or the LGPL are applicable instead
00030  * of those above. If you wish to allow use of your version of this file only
00031  * under the terms of either the GPL or the LGPL, and not to allow others to
00032  * use your version of this file under the terms of the MPL, indicate your
00033  * decision by deleting the provisions above and replace them with the notice
00034  * and other provisions required by the GPL or the LGPL. If you do not delete
00035  * the provisions above, a recipient may use your version of this file under
00036  * the terms of any one of the MPL, the GPL or the LGPL.
00037  *
00038  * ***** END LICENSE BLOCK ***** */
00039 /* $Id: bbs_rand.c,v 1.3 2004/04/27 23:04:37 gerv%gerv.net Exp $ */
00040 
00041 #include "bbs_rand.h"
00042 
00043 #define SEED     1
00044 #define MODULUS  2
00045 
00046 /* This modulus is the product of two randomly generated 512-bit
00047    prime integers, each of which is congruent to 3 (mod 4).          */
00048 static char *bbs_modulus = 
00049 "75A2A6E1D27393B86562B9CE7279A8403CB4258A637DAB5233465373E37837383EDC"
00050 "332282B8575927BC4172CE8C147B4894050EE9D2BDEED355C121037270CA2570D127"
00051 "7D2390CD1002263326635CC6B259148DE3A1A03201980A925E395E646A5E9164B0EC"
00052 "28559EBA58C87447245ADD0651EDA507056A1129E3A3E16E903D64B437";
00053 
00054 static int    bbs_init = 0;  /* flag set when library is initialized */
00055 static mp_int bbs_state;     /* the current state of the generator   */
00056 
00057 /* Suggested size of random seed data */
00058 int           bbs_seed_size = (sizeof(bbs_modulus) / 2);
00059 
00060 void         bbs_srand(unsigned char *data, int len)
00061 {
00062   if((bbs_init & SEED) == 0) {
00063     mp_init(&bbs_state);
00064     bbs_init |= SEED;
00065   }
00066 
00067   mp_read_raw(&bbs_state, (char *)data, len);
00068 
00069 } /* end bbs_srand() */
00070 
00071 unsigned int bbs_rand(void)
00072 {
00073   static mp_int   modulus;
00074   unsigned int    result = 0, ix;
00075 
00076   if((bbs_init & MODULUS) == 0) {
00077     mp_init(&modulus);
00078     mp_read_radix(&modulus, bbs_modulus, 16);
00079     bbs_init |= MODULUS;
00080   }
00081 
00082   for(ix = 0; ix < sizeof(unsigned int); ix++) {
00083     mp_digit   d;
00084 
00085     mp_sqrmod(&bbs_state, &modulus, &bbs_state);
00086     d = DIGIT(&bbs_state, 0);
00087 
00088     result = (result << CHAR_BIT) | (d & UCHAR_MAX);
00089   }
00090 
00091   return result;
00092 
00093 } /* end bbs_rand() */
00094 
00095 /*------------------------------------------------------------------------*/
00096 /* HERE THERE BE DRAGONS                                                  */