diff --git a/src/AppserverIo/Lang/String.php b/src/AppserverIo/Lang/String.php
index 4d2e4ef..897f989 100644
--- a/src/AppserverIo/Lang/String.php
+++ b/src/AppserverIo/Lang/String.php
@@ -413,16 +413,58 @@ public function trim()
     }
 
     /**
-     * md5 encryptes the string and returns the
+     * md5 encrypts the string and returns the
      * instance.
      *
+     * @param string $salt the salt to prepend to the stringValue
+     *
      * @return \AppserverIo\Lang\String The instance md5 encrypted
      */
-    public function md5()
+    public function md5($salt = null)
+    {
+        return $this->init(md5($salt . $this->stringValue()));
+    }
+
+    /**
+     * sha1 encrypts the string and returns the
+     * instance.
+     *
+     * @param string $salt the salt to prepend to the stringValue
+     *
+     * @return \AppserverIo\Lang\String The instance sha1 encrypted
+     */
+    public function sha1($salt = null)
+    {
+        return $this->init(hash('sha1', $salt . $this->stringValue()));
+    }
+
+    /**
+     * sha256 encrypts the string and returns the
+     * instance.
+     *
+     * @param string $salt the salt to prepend to the stringValue
+     *
+     * @return \AppserverIo\Lang\String The instance sha256 encrypted
+     */
+    public function sha256($salt = null)
     {
-        return $this->init(md5($this->stringValue()));
+        return $this->init(hash('sha256', $salt . $this->stringValue()));
     }
 
+    /**
+     * sha512 encrypts the string and returns the
+     * instance.
+     *
+     * @param string $salt the salt to prepend to the stringValue
+     *
+     * @return \AppserverIo\Lang\String The instance sha512 encrypted
+     */
+    public function sha512($salt = null)
+    {
+        return $this->init(hash('sha512', $salt . $this->stringValue()));
+    }
+
+
     /**
      * Converts the string value to upper case
      * and returns the instance.
diff --git a/tests/AppserverIo/Lang/StringTest.php b/tests/AppserverIo/Lang/StringTest.php
index 501cd71..fecb426 100644
--- a/tests/AppserverIo/Lang/StringTest.php
+++ b/tests/AppserverIo/Lang/StringTest.php
@@ -162,4 +162,43 @@ public function testValueOf()
         // check that String was successfully concatenated
         $this->assertTrue($string->equals(new String($string)));
     }
+
+    /**
+     * This test checks the String's sha1() method.
+     *
+     * @return void
+     */
+    public function testSha1()
+    {
+        // initialize a new String instance
+        $string = new String('Mustermann');
+        // check that String's sha1 summs equals
+        $this->assertTrue($string->sha1()->equals(new String(hash('sha1' , 'Mustermann'))));
+    }
+
+    /**
+     * This test checks the String's sha256() method.
+     *
+     * @return void
+     */
+    public function testSha256()
+    {
+        // initialize a new String instance
+        $string = new String('Mustermann');
+        // check that String's sha256 summs equals
+        $this->assertTrue($string->sha256()->equals(new String(hash('sha256' , 'Mustermann'))));
+    }
+
+    /**
+     * This test checks the String's sha512() method.
+     *
+     * @return void
+     */
+    public function testSha512()
+    {
+        // initialize a new String instance
+        $string = new String('Mustermann');
+        // check that String's sha512 summs equals
+        $this->assertTrue($string->sha512()->equals(new String(hash('sha512' , 'Mustermann'))));
+    }
 }