I'm trying to understand the behavior of pointer authentication instructions using the ARM Foundation Platform. I'm confused that Foundation Platform is allegedly configured with both implementation-defined and QARMA5 algorithms (because ID_AA64ISAR_EL1=13112111) despite the fact the ARM ARM says these are exclusive options.
Have I misunderstood? If not, can you state what algorithm is supported and whether this is configurable in any way?
Thanks.