Polymorphic encryption key allocation scheme

A method comprising:

• providing a key bundle comprising a first cryptographic key and an associated first cryptographic function identifier, the first cryptographic function identifier identifying a first cryptographic triple function and providing description of the first cryptographic function sufficient to derive the first cryptographic function;
• providing a key block corresponding to a subset difference tree, wherein the key block is selected by:
• determining, by a hardware processor, the first cryptographic triple function corresponding to the first cryptographic function identifier using at least the first cryptographic function identifier;
• traversing, by the hardware processor, the subset difference tree using the first cryptographic key and the first cryptographic triple function to obtain a content cryptographic key, the content cryptographic key being adapted for decryption of encrypted content.

A computer program product for broadcast encryption, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a hardware processor to cause the hardware processor to perform a method comprising:

• reading, by the hardware processor, a key bundle comprising a first cryptographic key and an associated first cryptographic function identifier, the first cryptographic function identifier identifying a first cryptographic triple function and providing description of the first cryptographic function sufficient to derive the first cryptographic function;
• receiving, by the hardware processor, a key block corresponding to a subset difference tree;
• determining, by the hardware processor, the first cryptographic triple function corresponding to the first cryptographic function identifier using at least the first cryptographic function identifier;
• traversing, by the hardware processor, the subset difference tree using the first cryptographic key and the first cryptographic triple function to obtain a content cryptographic key, the content cryptographic key being adapted for decryption of encrypted content.