tegencrypt.c - plan9port - [fork] Plan 9 from user space
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       ---
       tegencrypt.c (809B)
       ---
            1 #include "os.h"
            2 #include <mp.h>
            3 #include <libsec.h>
            4 
            5 mpint*
            6 egencrypt(EGpub *pub, mpint *in, mpint *out)
            7 {
            8         mpint *m, *k, *gamma, *delta, *pm1;
            9         mpint *p = pub->p, *alpha = pub->alpha;
           10         int plen = mpsignif(p);
           11         int shift = ((plen+Dbits)/Dbits)*Dbits;
           12         /* in libcrypt version, (int)(LENGTH(pub->p)*sizeof(NumType)*CHARBITS); */
           13 
           14         if(out == nil)
           15                 out = mpnew(0);
           16         pm1 = mpnew(0);
           17         m = mpnew(0);
           18         gamma = mpnew(0);
           19         delta = mpnew(0);
           20         mpmod(in, p, m);
           21         while(1){
           22                 k = mprand(plen, genrandom, nil);
           23                 if((mpcmp(mpone, k) <= 0) && (mpcmp(k, pm1) < 0))
           24                         break;
           25         }
           26         mpexp(alpha, k, p, gamma);
           27         mpexp(pub->key, k, p, delta);
           28         mpmul(m, delta, delta);
           29         mpmod(delta, p, delta);
           30         mpleft(gamma, shift, out);
           31         mpadd(delta, out, out);
           32         mpfree(pm1);
           33         mpfree(m);
           34         mpfree(k);
           35         mpfree(gamma);
           36         mpfree(delta);
           37         return out;
           38 }