arm64e pointer authentication: PAC keys, PACIASP, A12 sigreturn.com

The post explains how Apple’s arm64e pointer authentication uses five hardware-held keys and modifiers to sign pointers, with a hands-on Mac test measuring a 16-bit signature on user instruction pointers and showing that a wrong modifier causes a fault. It traces protections and gaps across Apple devices and software releases, including function-pointer signature reuse, the PACMAN research attack demonstrated on M1, and newer security monitors that restrict what kernel control can achieve.