While investigating the character ids used by Sony for EQ characters I found that the accounts are lumped together, so they create an easy way to find out an account’s characters given that one knows one of their names. It could be a quick side project to the trendy items project. I haven’t investigated it enough to say whether there’s interference here and there in the id sequence (which could make it a lot harder).

One way to investigate that would probably be to pick random ids and then sample the closest few ids to each random id (is it 5 characters per account in EQ?). If there are no jumps or interference in the complete id sequence then a pattern should emerge where the character in one specific position has a higher level than the characters in other positions (and the pattern should be periodic in the complete id sequence).

It could also possibly be used to find out when an account was created if one could collect enough reference data on creation times.