Memorytoken

Memorytoken is a formal term used in computer systems to denote a compact, portable handle that represents access rights to a specific region of memory. In capability-based architectures and security models, a memorytoken functions as a memory capability—a token that both identifies a memory object and encodes what operations are permitted, the size or bounds of the region, and provenance information. Memorytokens can be used to grant controlled sharing between processes, threads, or isolated execution domains without exposing raw pointers.

Typically a memorytoken includes fields such as a region identifier, offset, length, allowed operations, and a cryptographic or hardware-backed tag. The token is validated by a memory manager or capability oracle before access is allowed. Because tokens can be revoked or expired, they support dynamic memory sharing with strong isolation.

Memorytokens are used in microkernel and capability-based systems, memory-safe language runtimes, and high-performance data sharing where zero-copy techniques require safe transfer of memory rights. They provide a level of indirection that can prevent malformed or unauthorized access and reduce the risk of pointer corruption.

Security considerations include ensuring tokens cannot be forged, that revocation is timely, and that tokens are bound to the correct domain or process. Hardware support such as CHERI or protected memory architectures often implement tokens as capabilities with hardware enforcement.

See also: capability-based security, capability, memory protection, CHERI, capability machine.