Index: tests/Zend/Crypt/DiffieHellmanTest.php
===================================================================
--- tests/Zend/Crypt/DiffieHellmanTest.php	(revision 21515)
+++ tests/Zend/Crypt/DiffieHellmanTest.php	(working copy)
@@ -133,4 +133,12 @@
         $this->assertEquals($expectedSharedSecret, $aliceSecretKey);
         $this->assertEquals($expectedSharedSecret, $bobSecretKey);
     }
+    
+    public function testGenerateKeysWithUnsetPrivateKey()
+    {
+        $dh = new Zend_Crypt_DiffieHellman(563, 5);
+        $dh->generateKeys();
+        $privateKey = $dh->getPrivateKey();
+        $this->assertNotNull($privateKey);
+    }
 }
Index: library/Zend/Crypt/DiffieHellman.php
===================================================================
--- library/Zend/Crypt/DiffieHellman.php	(revision 21515)
+++ library/Zend/Crypt/DiffieHellman.php	(working copy)
@@ -324,7 +324,7 @@
     public function getPrivateKey($type = self::NUMBER)
     {
         if (!$this->hasPrivateKey()) {
-            $this->setPrivateKey($this->_generatePrivateKey());
+            $this->setPrivateKey($this->_generatePrivateKey(), self::BINARY);
         }
         if ($type == self::BINARY) {
             return $this->_math->toBinary($this->_privateKey);
@@ -377,4 +377,4 @@
         return $rand;
     }
 
-}
\ No newline at end of file
+}