Patent ID: 7383445

Claim:
A semiconductor storage device having a security function for imposing limitation on data rewriting, the semiconductor storage device comprising: at least one non-volatile memory cell array block which is capable of receiving concurrent electrical erasure, the at least one non-volatile memory cell array block comprising at least one main memory block region to store data, and at least one memory region configured to store a security release key corresponding to each of the at least one memory cell array block; at least one nonvolatile storage unit configured to store a security registration lock corresponding to each of the at least one memory cell array block; a determination circuit for comparing a value which is generated based on the security release key against a value which is generated based on the security registration lock to determine whether or not to grant release of the security function; and a memory cell array data output switching circuit for, when an output signal from the determination circuit indicates a matching result of comparison between the value which is generated based on the security release key and the value which is generated based on the security registration lock, permitting data which is read from a corresponding one of the at least one memory cell array block to be externally output.