Exploring the RP2350 Security

Raspberry Pi's Novel "Security through Transparency" Approach

- Colin O'Flynn

Raspberry Pi's RP2350 MCU has more memory, faster processors, and lower power states compared to its predecessor, the RP2340. In this month's article, Colin explores some additional features. He emphasizes transparency, enhanced security with its innovative boot ROM and redundancy coprocessor, and glitch protection. He then shares the results of Raspberry Pi's “hacking challenge” to identify and fix security vulnerabilities in the chip.

Recently, Raspberry Pi introduced the RP2350 microcontroller, which has a huge amount of features under the hood. If you've used the older RP2040, you know it was already an interesting device, with unique features such as a high-speed "Programmable In Out" (PIO) block that allowed you to effectively bit bang high-speed protocols using a special-purpose peripheral block. But the RP2040 looks tame compared to the RP2350. One of the most ambitious features is that the entire architecture of the device can be changed. The RP2350 can be booted in two modes, a dual-core Cortex-M33 (ARM Cortex) mode, or a dual-core Hazard3 (RISC-V) mode.

One of the main features missing from the RP2040 was code security. The device booted off an external SPI flash, which meant that anybody could easily read out the flash memory. Making a secure system primarily meant using an external device that provided a secure boot, but adding an external device negated the low-cost advantage of the RP2040.