1. A method comprising: receiving, at a device, a verification key including an identifier of a parent verification key of the verification key, wherein the verification key comprises a constraint portion; determining, at the device, whether the constraint portion of the verification key matches a subset of a constraint portion of the parent verification key, the subset being less than all of the constraint portion of the parent verification key; associating, by the device, in case the constraint portion of the verification key matches the subset of the constraint portion of the parent verification key, the verification key with a particular state update; and storing, by the device, the verification key associated with the particular state update.