TF-A stands for trusted-firmware A (aka arm-trusted-firmware) is a first stage boot loader runs on many ARM core. Especially for aarch64. This talk introduces how to use TF-A on RPi3. And why it brings us a step further for fully open source bootloaders for RPI3. How to tweak the FIP images. How to sign FIP images thus we can enable trusted-boot on RPi3. And also we can demo the tool rpi3-cst for hack the BL1/BL2 key hash and to break the Trusted-boot to show that why RPi3 isn't secure at all.