Black Box Probing: a Security Analysis of Xiaomi's MJA1 Secure Chip (opens in new tab)

Xiaomi's MJA1 is a proprietary secure chip used in their recent cameras to protect sensitive data and device communications. With no public documentation available, we conducted a black-box security analysis covering hardware identification, I2C sniffing, flash dumping, and firmware reverse engineering. This post walks through how we mapped the chip's command protocol, brute-forced undocumented commands, and assessed its security properties.