92 lines
1.7 KiB
C
92 lines
1.7 KiB
C
/*
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* Digital Signature Standard
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*
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* See Communications ACM July 1992, Vol. 35 No. 7
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* This new standard for digital signatures has been proposed by
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* the American National Institute of Standards and Technology (NIST)
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* under advisement from the National Security Agency (NSA).
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*
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* This program generates the common values p, q and g to a file
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* common.dss
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*/
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#include <stdio.h>
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#include "miracl.h"
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#define QBITS 160
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#define PBITS 1024
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int main()
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{
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FILE *fp;
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big p,q,h,g,n,s,t;
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long seed;
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miracl *mip=mirsys(100,0);
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p=mirvar(0);
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q=mirvar(0);
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h=mirvar(0);
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g=mirvar(0);
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n=mirvar(0);
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s=mirvar(0);
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t=mirvar(0);
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/* randomise */
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printf("Enter 9 digit random number seed = ");
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scanf("%ld",&seed);
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getchar();
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irand(seed);
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/* generate q */
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forever
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{
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bigbits(QBITS,q);
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nxprime(q,q);
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if (logb2(q)>QBITS) continue;
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break;
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}
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printf("q= ");
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cotnum(q,stdout);
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/* generate p */
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expb2(PBITS,t);
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decr(t,1,t);
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premult(q,2,n);
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divide(t,n,t);
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expb2(PBITS-1,s);
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decr(s,1,s);
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divide(s,n,s);
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forever
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{
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bigrand(t,p);
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if (mr_compare(p,s)<=0) continue;
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premult(p,2,p);
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multiply(p,q,p);
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incr(p,1,p);
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copy(p,n);
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if (isprime(p)) break;
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}
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printf("p= ");
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cotnum(p,stdout);
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/* generate g */
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do {
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decr(p,1,t);
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bigrand(t,h);
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divide(t,q,t);
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powmod(h,t,p,g);
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} while (size(g)==1);
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printf("g= ");
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cotnum(g,stdout);
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fp=fopen("common.dss","wt");
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fprintf(fp,"%d\n",PBITS);
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mip->IOBASE=16;
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cotnum(p,fp);
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cotnum(q,fp);
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cotnum(g,fp);
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fclose(fp);
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return 0;
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}
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