A method of performing a secure function on data inputs by a security module, including: receiving an encrypted data value by the security module; decrypting the encrypted data value using a white-box decryption block cipher and encoding the decrypted data value, wherein the data value is invisible to an attacker; performing a function on the encoded data value and producing an encoded result of the function, wherein the data value and the result are invisible to the attacker; decoding the encoded result of the programmed function and then encrypting the result using a white-box encryption block cipher, wherein the result is invisible to the attacker.