1. A method performed on a computing device that includes at least one processor and memory, the method comprising: receiving, by the computing device, two or more subtokens, each of a fixed size, the subtokens together representing a larger token of a size larger than the fixed size, the larger token representing data that is immutable as long as the larger token is valid; obtaining, by the computing device from one or more of the subtokens, a cryptographically secure key and information that identifies a source from which the data represented by the lamer token is obtainable; and providing, by the computing device to an offload provider that comprises at least one other computing device that is separate from the computing device, evidence of the key to obtain a portion of the data represented by the larger token without the portion of the data passing through an initiator that provided the subtokens.