The present invention relates to a secure method of distributing configuration data for a programmable logic device (PLD). The configuration data is encrypted to generate encrypted configuration data. A decryption key is encrypted using a silicon key. The encrypted configuration data and the encrypted decryption key are transferred to a PLD. Within the PLD, the encrypted decryption key is decrypted using the silicon key. Then, also within the PLD, the encrypted configuration data is decrypted using the decryption key to recover the configuration data. The PLD is then configured using the configuration data. The silicon key may be communicated to the PLD by tying predetermined input pins to an active high voltage level or signal ground, to form a binary code.