45.1 Overview

The TrustRAM (TRAM) module is the controller interface for an 8 KB security RAM. This RAM is intended for volatile secret data. The TRAM module is capable of performing address map scrambling for both write and read access to the security RAM. It can also perform data scrambling on write access, and data descrambling on read access. To improve side-channel attack resistance the TRAM module can perform silent access of the data stream from security RAM.

The TRAM module can execute two automated tasks that are triggered by external events: remanence prevention and erase. When a remanence periodic event occurs, the physical data stored in the security RAM is inverted in order to prevent physical “burn-in” signatures. When a tamper event occurs, the TRAM module executes a full erasure of scramble key as well as the data in the security RAM. Both automated tasks do not require CPU interaction and can be performed in all sleep modes.