src/Zend/Filter/Encrypt/Openssl.php
public function setCompression($compression)
    {
        if (is_string($this->_compression)) {
            $compression = array('adapter' => $compression);
        }

        $this->_compression = $compression;
        return $this;
    }
public function setCompression($compression)
    {
        if (is_string($this->_compression)) {
            $compression = array('adapter' => $compression);
        }

        $this->_compression = $compression;
        return $this;
    }
Sets a internal compression for values to encrypt

@param string|array $compression
@return Zend_Filter_Encrypt_Openssl