Subset-difference broadcast encryption with blacklisting

A computer program product for blacklisting in a subset-difference broadcast encryption scheme, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform a method comprising:

• determining a blacklisted node covered by a first subset, the first subset having an apex node;
• determining a plurality of subsets, each of the plurality of subsets having an apex node inferior to the apex node of the first subset, none of the plurality of subsets covering the blacklisted node;
• determining a subset-difference tree comprising the plurality of subsets and not including the first subset;
• and
• generating a key block corresponding to the subset-difference tree.

A system comprising:

• an encryption key block generator comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor of the encryption key block generator to cause the processor to perform a method comprising:
• determining a blacklisted node covered by a first subset, the first subset having an apex node;
• determining a plurality of subsets, each of the plurality of subsets having an apex node inferior to the apex node of the first subset, none of the plurality of subsets covering the blacklisted node;
• determining a subset-difference tree comprising the plurality of subsets and not including the first subset;
• and
• generating a key block corresponding to the subset-difference tree.