I can confirm what another post said. There's a Disembodied Leg on a table down in Ryker's basement that, when eaten by my Scholar elf, granted the password for the chest. This is not the same leg you dig up for the "Stranger in a Strange Land" quest, and the quest won't update after you eat the leg. But when you next speak to the chest, the option will be there. I don't know if you need to eat the leg after speaking to the chest for the first time, nor do I know if a non-Scholar elf can do it.