dh.h File Reference

Classes for Diffie-Hellman key exchange. More...

#include "cryptlib.h"
#include "gfpcrypt.h"
#include "algebra.h"

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Classes
class	DH_Domain< GROUP_PARAMETERS, COFACTOR_OPTION >
	Diffie-Hellman domain. More...

Typedefs
typedef DH_Domain< DL_GroupParameters_GFP_DefaultSafePrime >	DH
	Diffie-Hellman in GF(p) More...

Variables
CRYPTOPP_DLL_TEMPLATE_CLASS	DH_Domain< DL_GroupParameters_GFP_DefaultSafePrime >

Detailed Description

Classes for Diffie-Hellman key exchange.

Definition in file dh.h.

Typedef Documentation

typedef DH_Domain<DL_GroupParameters_GFP_DefaultSafePrime> DH

Diffie-Hellman in GF(p)

DH() class is a typedef of DH_Domain(). The documentation that follows does not exist. Rather the documentation was created in response to Issue 328, Diffie-Hellman example code not compiling.

Generally speaking, a DH() object is ephemeral and is intended to execute one instance of the Diffie-Hellman protocol. The private and public key parts are not intended to be set or persisted. Rather, a new set of domain parameters are generated each time an object is created.

Once a DH() object is created, once can retrieve the ephemeral public key for the other party with code similar to the following.

   AutoSeededRandomPool prng;
  Integer p, q, g;
  PrimeAndGenerator pg;

  pg.Generate(1, prng, 512, 511);
  p = pg.Prime();
  q = pg.SubPrime();
  g = pg.Generator();

  DH dh(p, q, g);
  SecByteBlock t1(dh.PrivateKeyLength()), t2(dh.PublicKeyLength());
  dh.GenerateKeyPair(prng, t1, t2);
  Integer k1(t1, t1.size()), k2(t2, t2.size());

  cout << "Private key:\n";
  cout << hex << k1 << endl;

  cout << "Public key:\n";
  cout << hex << k2 << endl;

Output of the program above will be similar to the following.

   $ ./cryptest.exe
  Private key:
  72b45a42371545e9d4880f48589aefh
  Public key:
  45fdb13f97b1840626f0250cec1dba4a23b894100b51fb5d2dd13693d789948f8bfc88f9200014b2
  ba8dd8a6debc471c69ef1e2326c61184a2eca88ec866346bh

See also

Diffie-Hellman on the Crypto++ wiki and Diffie-Hellman in GF(p) with key validation

Since

Crypto++ 1.0

Definition at line 270 of file dh.h.

Variable Documentation

CRYPTOPP_DLL_TEMPLATE_CLASS DH_Domain< DL_GroupParameters_GFP_DefaultSafePrime >

Definition at line 169 of file dh.h.