protection of encrypted data Integrity using an intermediate cipher state to generate a signature

摘要

The method involves providing an intermediary state to be identical in ciphering and deciphering processes, where the intermediary state is sampled during ciphering to generate a signature. The signature together with ciphered data is stored in a memory (2) external to a processor executing ciphering algorithm, where the ciphering algorithm is designed as a Advanced Encryption Standard (AES) type symmetrical algorithm. The signature is calculated by an XOR-type combination of portions of the intermediary result. Independent claims are also included for the following: (1) a method for recording data in a memory (2) a method for reading data stored in a memory (3) an electronic system comprising a processing unit.