ID-BASED ADDITIVE HOMOMORPHIC ENCRYPTION METHOD

摘要

PURPOSE: An identification (ID) based summation homomorphism type encryption method is provided to effectively manage keys of a summation homomorphism code. CONSTITUTION: A key generating center includes a module using an algorithm inputting a stability parameter and generates a sub-group G of a circulation group including a generator g (S300). A key generating center generates a master key comprising a prim factor p and q and generates a system parameter (pk) based on the generator g, the sub-group G, and a random function (S310). The key generating center outputs a user secret key with a discrete algebra value based on the generator g by using an algorithm inputting a master key, the generator g, the sub-group G, and a function for a user ID (S320). [Reference numerals] (AA) Start; (BB) Finish; (S300) Form a sub-group G of Z^*_N^2 having a generator g; (S310) Form a master key (sk) composed of p and q which are factorization values of a system parameter (pk) and N; (S320) Form a user secret key by using a function having a range of the sub-group G in respect to a user ID; (S330) Encode messages by using the system parameter and user ID; (S340) Descramble the encoded messages by using the system parameter and user secrete key