Protecting a programmable memory against unauthorized modification

An electronic device comprising:

• a programmable memory, the memory comprising at least one protected memory field;
• a data write path for writing data into the memory, the data write path comprising a decryption unit that is adapted for receiving encrypted data, decrypting the encrypted data, and writing resulting plain data into the at least one protected memory field;
• a data read path for reading data from the memory, the data read path being adapted for reading out the plain data stored in the protected memory field, whereby the at least one protected memory field is only writable by applying the data to be written into the at least one protected memory field in encrypted form to the data write path;
• a controller unit, wherein the controller unit comprises a CPU, the decryption unit and a decryption key storage containing a secret key;
• a memory unit, the memory unit comprising the programmable memory;
• and
• wherein the decryption key storage is adapted to be only readable by the decryption unit.

A method for providing an update to an integrated semiconductor memory unit,

• wherein the integrated semiconductor memory unit comprises a programmable memory, a data write path for writing data into the memory and a data read path for reading data from the memory,
• the memory comprising at least one protected memory field,
• the data write path comprising a decryption unit that is adapted for receiving encrypted data, decrypting the encrypted data, and writing resulting plain data into the at least one protected memory field,
• the data read path being adapted for reading out the plain data stored in the protected memory field,
• whereby the at least one protected memory field is only writable by applying the data to be written into the at least one protected memory field in encrypted form to the data write path,
• further comprising a decryption key storage containing a secret key, wherein the decryption key storage is adapted to be only readable by the decryption unit,
• the method comprising:
• creating encrypted data on the basis of plain data to be written into the integrated semiconductor memory unit, and
• providing the encrypted data to the integrated semiconductor memory unit for decryption and storage within the integrated semiconductor memory unit.

A method for providing an update to an electronic device,

• wherein the electronic device comprises a programmable memory, a data write path for writing data into the memory and a data read path for reading data from the memory,
• the memory comprising at least one protected memory field,
• the data write path comprising a decryption unit that is adapted for receiving encrypted data, decrypting the encrypted data, and writing resulting plain data into the at least one protected memory field,
• the data read path being adapted for reading out the plain data stored in the protected memory field,
• whereby the at least one protected memory field is only writable by applying the data to be written into the at least one protected memory field in encrypted form to the data write path,
• the electronic device comprising a controller unit and a memory unit, the memory unit comprising the programmable memory,
• wherein the controller unit comprises a CPU, the decryption unit and a decryption key storage containing a secret key, and
• wherein the decryption key storage is adapted to be only readable by the decryption unit,
• the method comprising:
• creating encrypted data on the basis of plain data to be written into the electronic device, and
• providing the encrypted data to the electronic device for decryption and storage within the electronic device.