PROTECTING A PROGRAMMABLE MEMORY AGAINST UNAUTHORIZED MODIFICATION

摘要

An apparatus comprises a programmable memory (24), a data write path (30) for writing data into the memory (24) and a data read path (38) for reading data from the memory (24). The memory (24) comprises at least one protected memory field (42). The data write path (30) comprises a decryption unit (32) that is adapted for receiving encrypted data (ED), decrypting the encrypted data (ED), and writing resulting plain data (PD) into the at least one protected memory field (42). The data read path (38) is adapted for reading out the plain data (PD) stored in the protected memory field (42). The at least one protected memory field (42) is only writable by applying the data to be written into the at least one protected memory field (42) in encrypted form to the data write path (30). The invention further comprises an electronic device (10), an external data source (44), a method for accessing the programmable memory (24), and a method for providing an update to an electronic device (10). The invention provides a technique for protecting the integrity of the electronic device (10) by preventing attacks in which unauthorized data - the data being program code and/or other information - is stored in the programmable memory (24).