The present invention provides systems and methods for controlling the use of processing algorithms, and applications thereof. In an embodiment, authorization to use an algorithm is validated in a system having a processor capable of executing user defined instructions, by executing a user defined instruction that writes a first value to a first storage of a user defined instruction block, uses the first value to transform a second value located in a second storage of the user defined instruction block, and compares the transformed second value to a third value located in a third storage. Use of the algorithm is permitted only if the comparison of the transformed second value to the third value indicates that use of the algorithm is authorized. In another embodiment, authorization to use an at least partially decrypted algorithm is validated via a key for enablement.