egdecrypt.c (563B)
1 #include "os.h" 2 #include <mp.h> 3 #include <libsec.h> 4 5 mpint* 6 egdecrypt(EGpriv *priv, mpint *in, mpint *out) 7 { 8 EGpub *pub = &priv->pub; 9 mpint *gamma, *delta; 10 mpint *p = pub->p; 11 int plen = mpsignif(p)+1; 12 int shift = ((plen+Dbits-1)/Dbits)*Dbits; 13 14 if(out == nil) 15 out = mpnew(0); 16 gamma = mpnew(0); 17 delta = mpnew(0); 18 mpright(in, shift, gamma); 19 mpleft(gamma, shift, delta); 20 mpsub(in, delta, delta); 21 mpexp(gamma, priv->secret, p, out); 22 mpinvert(out, p, gamma); 23 mpmul(gamma, delta, out); 24 mpmod(out, p, out); 25 mpfree(gamma); 26 mpfree(delta); 27 return out; 28 }