Subversion Repositories planix.SVN

#include "os.h"
#include <mp.h>
#include <libsec.h>

mpint*
egdecrypt(EGpriv *priv, mpint *in, mpint *out)
{
        EGpub *pub = &priv->pub;
        mpint *gamma, *delta;
        mpint *p = pub->p;
        int plen = mpsignif(p)+1;
        int shift = ((plen+Dbits-1)/Dbits)*Dbits;

        if(out == nil)
                out = mpnew(0);
        gamma = mpnew(0);
        delta = mpnew(0);
        mpright(in, shift, gamma);
        mpleft(gamma, shift, delta);
        mpsub(in, delta, delta);        
        mpexp(gamma, priv->secret, p, out);
        mpinvert(out, p, gamma);
        mpmul(gamma, delta, out);
        mpmod(out, p, out);
        mpfree(gamma);
        mpfree(delta);
        return out;
}