Secure SoC Version Directory for External Memory Freshness
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Solution Overview
Problem
In systems on a chip (SOC) with a secure element, data stored in external memory is vulnerable to rollback attacks and freshness verification is difficult without remote server connection, posing security risks.
Innovation Solution
A system on a chip with a secure element that includes a processing unit to control data storage and versioning in external rewritable non-volatile memory, using a dedicated directory and secure volatile memory to ensure data freshness by associating object identifiers with current versions and recording these in secure non-volatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored in external rewritable non-volatile memory to reduce costs and improve durability, then storage capacity and durability are improved, but security against rollback attacks deteriorates
Solution Approach 1:
The system performs preliminary actions by storing version identifiers in the secure element before writing data to external memory. When data is written to external memory, the corresponding version identifier is first committed to the secure element's non-volatile memory. This preliminary recording ensures that even if external memory is tampered with, the secure element retains the authentic version information needed to detect rollback attacks.
Solution Approach 2:
The version identifier acts as an intermediary between the data stored in external memory and the security verification process. Instead of directly verifying data authenticity, the system uses the version identifier stored in the secure element as a mediator to indirectly verify whether the data in external memory is current and has not been rolled back to an older version.
2Reliability
If remote server connection is used to verify data freshness, then security verification capability is improved, but system complexity and operational requirements deteriorate
Solution Approach 1:
The secure element performs self-service by autonomously verifying data freshness using its own internal non-volatile memory to store version identifiers. The processing unit compares version identifiers locally without needing to contact external servers. This self-contained verification mechanism eliminates the need for remote server connections while maintaining security, allowing the system to operate independently in offline environments.
3Reliability
If version identifiers are stored in secure non-volatile memory, then data freshness verification capability is improved, but memory usage increases
Solution Approach 1:
The system extracts only the essential version identifier information from the complete data set and stores it separately in the secure element's non-volatile memory. Instead of storing entire data copies or complex verification structures, only compact version identifiers are retained in the secure element, while the actual data remains in external memory. This extraction approach minimizes the storage burden on the secure element while maintaining verification capability.
Data Source
AI summary
The invention relates to a system on a chip comprising a secure element comprising a processing unit that is configured to send instructions to a rewritable non-volatile memory external to the system on a chip and connected thereto, the secure element further comprising a secure non-volatile memory and a secure volatile memory, wherein the processing unit of the system on a chip is configured to control:the storage, in the rewritable non-volatile memory of at least one object having a current version, and of a dedicated directory associating an identifier of each object with an identifier of the current version of this object, the dedicated directory further comprising an identifier of its own current version; andthe storage, in the non-volatile memory of the secure element, of the identifier of the current version of the dedicated directory