This package unites all types of identification used in the Casper network. The majority of them are represented as 32-byte hashes, although some of them contain prefixes (such as account, contract, contract package, and transfer).
The Key represents a complex and universal key type used in the Casper network. (See documentation for more information.)
The Unforgeable Reference (URef) stores access rights apart from the hash and prefix. (See documentation for more information.)
The exception to the 32-byte hash rule is the identifier for the Era, which is represented as a uint value. (See documentation for more information.)