tegsign.c - plan9port - [fork] Plan 9 from user space
  HTML git clone git://src.adamsgaard.dk/plan9port
   DIR Log
   DIR Files
   DIR Refs
   DIR README
   DIR LICENSE
       ---
       tegsign.c (810B)
       ---
            1 #include "os.h"
            2 #include <mp.h>
            3 #include <libsec.h>
            4 
            5 EGsig*
            6 egsign(EGpriv *priv, mpint *m)
            7 {
            8         EGpub *pub = &priv->pub;
            9         EGsig *sig;
           10         mpint *pm1, *k, *kinv, *r, *s;
           11         mpint *p = pub->p, *alpha = pub->alpha;
           12         int plen = mpsignif(p);
           13 
           14         pm1 = mpnew(0);
           15         kinv = mpnew(0);
           16         r = mpnew(0);
           17         s = mpnew(0);
           18         k = mpnew(0);
           19         mpsub(p, mpone, pm1);
           20         while(1){
           21                 mprand(plen, genrandom, k);
           22                 if((mpcmp(mpone, k) > 0) || (mpcmp(k, pm1) >= 0))
           23                         continue;
           24                 mpextendedgcd(k, pm1, r, kinv, s);
           25                 if(mpcmp(r, mpone) != 0)
           26                         continue;
           27                 break;
           28         }
           29         mpmod(kinv, pm1, kinv);  /* make kinv positive */
           30         mpexp(alpha, k, p, r);
           31         mpmul(priv->secret, r, s);
           32         mpmod(s, pm1, s);
           33         mpsub(m, s, s);
           34         mpmul(kinv, s, s);
           35         mpmod(s, pm1, s);
           36         sig = egsigalloc();
           37         sig->r = r;
           38         sig->s = s;
           39         mpfree(pm1);
           40         mpfree(k);
           41         mpfree(kinv);
           42         return sig;
           43 }