In AIX Maintenance mode, /dev/random and /dev/urandom are not configured.  This can be done manually like this to help recover the functionality though it's not readily available to start with:

# [[ -r /dev/random ]] && rm -rf /dev/random;
# [[ -r /dev/urandom ]] && rm -rf /dev/urandom;
# mknod /dev/random c 39 0;
# mknod /dev/random c 39 1;
# mkdir -p /etc/security;
# randomctl -l;

As a one liner:

# [[ -r /dev/random ]] && rm -rf /dev/random; [[ -r /dev/urandom ]] && rm -rf /dev/urandom; mknod /dev/random c 39 0; mknod /dev/random c 39 1; mkdir -p /etc/security; randomctl -l;

This is normally for the enhanced maintenance mode so you can perform more advanced OS tasks in helping system recovery.

Cheers,
TK