Enhanced security memory access method and architecture

A method to allow access to a memory device by an external device, the method including

• receiving at the memory device an access request to a selected storage area by the external device;
• in case the selected storage area is not a freely accessible area, performing an unlock procedure including:
• having the memory issuing to the external device a first code;
• at the external device, receiving the first code and, responsive thereto, sending to the memory device a second code depending on the first code;
• at the memory device, at least temporarily unlocking the selected storage area to allow access thereto by the external device based on the received second code,
• wherein said first code issued by the memory device to an external device upon receiving an access request is changed after performing predetermined number of unlock procedures.

An integrated circuit, comprising:

• a memory location operable to store data;
• and
• a control circuit operable to,
• send a first code value to a requestor external to the integrated circuit in response to a request from the requestor to access the memory location,
• receive a second code value from the requestor after sending the first code value,
• compare the second code value to a predetermined code value, and
• allow the requestor limited access to the memory location if the second code value has a predetermined relationship to the predetermined code value.

An integrated circuit, comprising:

• a code-value generator;
• and
• a control circuit coupled to the code-value generator and operable to
• send an address to a destination external to the integrated circuit,
• request a first code value from the destination,
• cause the generator to generate a second code value from the first code value,
• send the second code value to the destination,
• access a data-storage location of the destination corresponding to the address during a first period after sending the second code value,
• request a third code value from the destination after the first period expires,
• cause the generator to generate a fourth code value from the third code value,
• send the fourth code value to the destination, and
• access the data-storage location during a second period after sending the fourth code value.

An electronic system, comprising:

• a first integrated circuit;
• and
• a second integrated circuit coupled to the first integrated circuit and including
• a memory location operable to store data, and
• a control circuit operable to,
• send a first code value to the first integrated circuit in response to a request from the first integrated circuit to access the memory location,
• receive a second code value from the first integrated circuit after sending the first code value,
• compare the second code value to a predetermined code value, and
• allow the first integrated circuit limited access to the memory location if the second code value has a predetermined relationship to the predetermined code value.

An electronic system, comprising:

• a first integrated circuit having a data-storage location;
• and
• a second integrated circuit coupled to the first integrated circuit and including
• a code-value generator, and
• a control circuit coupled to the code-value generator and operable to
• send an address of the data-storage location to the first integrated circuit,
• request a first code value from the first integrated circuit,
• cause the generator to generate a second code value from the first code value,
• send the second code value to the first integrated circuit,
• access the data-storage location during a first period after sending the second code value,
• request a third code value from the first integrated circuit after the first period expires,
• cause the generator to generate a fourth code value from the third code value,
• send the fourth code value to the first integrated circuit, and
• access the data-storage location during a second period after sending the fourth code value.

A method, comprising:

• sending a first code value to a first integrated circuit in response to a request for access by the first integrated circuit to a memory location of a second integrated circuit;
• comparing a predetermined code value to a second code value generated by the first integrated circuit in response to the first code value;
• and
• allowing the first integrated circuit limited access the memory location of the second integrated circuit if the second code value has a predetermined relationship to the predetermined code value.

A method, comprising:

• sending an address to a first integrated circuit;
• requesting a first code value from the first integrated circuit;
• generating a second code value from the first code value;
• sending the second code value to the first integrated circuit;
• accessing a data-storage location of the first integrated circuit corresponding to the address during a first period after sending the second code value;
• requesting a third code value from the destination after the first period expires;
• causing the generator to generate a fourth code value from the third code value;
• sending the fourth code value to the destination;
• and
• accessing the data-storage location during a second period after sending the fourth code value.

An integrated circuit, comprising:

• a memory location operable to store data;
• and
• a control circuit operable to,
• send a first code value to a requester external to the integrated circuit in response to a request from the requestor to access the memory location,
• receive a second code value from the requestor after sending the first code value,
• compare the second code value to a predetermined code value,
• allow the requestor access to the memory location if the second code value has a predetermined relationship to the predetermined code value, and
• change the first code value after allowing the requester access to the memory location.

An electronic system, comprising:

• a first integrated circuit;
• and
• a second integrated circuit coupled to the first integrated circuit and including
• a memory location operable to store data, and
• a control circuit operable to,
• send a first code value to the first integrated circuit in response to a request from the first integrated circuit to access the memory location,
• receive a second code value from the first integrated circuit after sending the first code value,
• compare the second code value to a predetermined code value,
• allow the first integrated circuit access to the memory location if the second code value has a predetermined relationship to the predetermined code value, and
• change the first code value after allowing the requestor access to the memory location.

A method, comprising:

• sending a first code value to a first integrated circuit in response to a request for access by the first integrated circuit to a memory location of a second integrated circuit;
• comparing a predetermined code value to a second code value generated by the first integrated circuit in response to the first code value;
• allowing the first integrated circuit access the memory location of the second integrated circuit if the second code value has a predetermined relationship to the predetermined code value;
• and
• changing the first code value after allowing the first integrated circuit access to the memory location.