Microcontroller having security means

Abstract

Abstract A micro controller which has a first memory (5) in which invertedly enciphered program data is stored, a second memory (7) which stores cipher key data necessary for decoding the password stored in the first memory, a CPU (1) which controls writing data to or reading data from the first and second memories and a unit (9) which descrambles the cipher in the program data stored in the first memory based on the key data stored in the second memory, when the CPU accesses the first memory. The operation of this CPU is based on the program data which is decoded using the descrambling unit, which makes it possible to effectively block decoding or altering of programs and data.

Inventors

• 👤 Yasuo Saito

Bibliographic Details