diff --git a/programs/pkey/dh_genprime.c b/programs/pkey/dh_genprime.c
new file mode 100644
index 0000000..09d9b1d
--- /dev/null
+++ b/programs/pkey/dh_genprime.c
@@ -0,0 +1,122 @@
+/*
+ *  Diffie-Hellman-Merkle key exchange (prime generation)
+ *
+ *  Copyright (C) 2006-2007  Christophe Devine
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _CRT_SECURE_NO_DEPRECATE
+#define _CRT_SECURE_NO_DEPRECATE 1
+#endif
+
+#include <stdio.h>
+
+#include "xyssl/bignum.h"
+#include "xyssl/config.h"
+#include "xyssl/havege.h"
+
+/*
+ * Note: G = 4 is always a quadratic residue mod P,
+ * so it is a generator of order Q (with P = 2*Q+1).
+ */
+#define DH_P_SIZE 1024
+#define GENERATOR "4"
+
+int main( void )
+{
+    int ret = 1;
+
+#if defined(XYSSL_GENPRIME)
+    mpi G, P, Q;
+    havege_state hs;
+    FILE *fout;
+
+    mpi_init( &G, &P, &Q, NULL );
+    mpi_read_string( &G, 10, GENERATOR );
+
+    printf( "\n  . Seeding the random number generator..." );
+    fflush( stdout );
+
+    havege_init( &hs );
+
+    printf( " ok\n  . Generating the modulus, please wait..." );
+    fflush( stdout );
+
+    /*
+     * This can take a long time...
+     */
+    if( ( ret = mpi_gen_prime( &P, DH_P_SIZE, 1,
+                               havege_rand, &hs ) ) != 0 )
+    {
+        printf( " failed\n  ! mpi_gen_prime returned %d\n\n", ret );
+        goto exit;
+    }
+
+    printf( " ok\n  . Verifying that Q = (P-1)/2 is prime..." );
+    fflush( stdout );
+
+    if( ( ret = mpi_sub_int( &Q, &P, 1 ) ) != 0 )
+    {
+        printf( " failed\n  ! mpi_sub_int returned %d\n\n", ret );
+        goto exit;
+    }
+
+    if( ( ret = mpi_div_int( &Q, NULL, &Q, 2 ) ) != 0 )
+    {
+        printf( " failed\n  ! mpi_div_int returned %d\n\n", ret );
+        goto exit;
+    }
+
+    if( ( ret = mpi_is_prime( &Q, havege_rand, &hs ) ) != 0 )
+    {
+        printf( " failed\n  ! mpi_is_prime returned %d\n\n", ret );
+        goto exit;
+    }
+
+    printf( " ok\n  . Exporting the value in dh_prime.txt..." );
+    fflush( stdout );
+
+    if( ( fout = fopen( "dh_prime.txt", "wb+" ) ) == NULL )
+    {
+        ret = 1;
+        printf( " failed\n  ! Could not create dh_prime.txt\n\n" );
+        goto exit;
+    }
+
+    if( ( ret = mpi_write_file( "P = ", &P, 16, fout ) != 0 ) ||
+        ( ret = mpi_write_file( "G = ", &G, 16, fout ) != 0 ) )
+    {
+        printf( " failed\n  ! mpi_write_file returned %d\n\n", ret );
+        goto exit;
+    }
+
+    printf( " ok\n\n" );
+    fclose( fout );
+
+exit:
+
+    mpi_free( &Q, &P, &G, NULL );
+#else
+    printf( "\n  ! Prime-number generation is not available.\n\n" );
+#endif
+
+#ifdef WIN32
+    printf( "  Press Enter to exit this program.\n" );
+    fflush( stdout ); getchar();
+#endif
+
+    return( ret );
+}