Block is the unit within a blockchain that stores transactions and transaction-related data, typically composed of a block header and block body.


A distributed structure formed by consensus-confirmed blocks which are connected in chronological order.

Smart Contract

A contract defined in digital form that can automatically execute clauses.


Also referred to as an event, it is a recorded instance of atomic ledger data state change, its process, and outcome on the blockchain.

Transaction Hash

The unique hash value generated after a successful transaction is recorded on the blockchain.

Peer-to-peer Networking

A computer network consisting only of nodes that are equivalent in terms of control and operational capabilities.

TEE (Trusted Execution Environment)

Provides hardware-level resource isolation and trust measurement capabilities, with Intel SGX being the most representative example.


Defaultly computed by the SHA-256 algorithm, it's an encrypted string displayed in hexadecimal format.

Merkle root

In the construction of a Merkle tree, the final unique hash value calculated by pairwise computations from bottom to top is known as the Merkle root.


Each slot generates a block, and in CESS, the duration of a slot is 6 seconds.


Based on BABE algorithm, an epoch is a time period divided into smaller time slots. Each slot has at least one slot leader, who has the authority to propose a block.


A collection of six epochs. At the end of each era, the consensus rewards for that era are settled. In the fifth epoch, the validator list for the next era is elected.

PoDR²(Proof of Data Reduplication and Recovery)

Data duplication and recovery proof algorithm, used to prove the authenticity of the data.

Random/reputation-based round-robin selection consensus algorithm, underlying based on Polkadot's GRANDPA and NPoS consensus algorithms.

cid(Content Identifier)

Content identifier, used to uniquely identify a specific piece of data content.

Data segment

Dividing a complete data file according to storage specifications, splitting it into fixed-sized data segments.

Data fragment

The data fragment formed after applying redundancy encoding to segments.

Data chunk

When challenging data, data chunk are formed by dividing the fragments into smaller chunk

Data Marking

The Enclave of the TEE Worker is responsible for processing file F and generating a signature-based tag for later proof generation and verification. The TEE Worker sends the output parameters along with file F to storage nodes for storage. The process of invoking this algorithm is also referred to as "Marking."

TEE Worker

Primarily responsible for marking data and generating random data for storage nodes to verify their idle space.


A stack-based virtual machine instruction format. In CESS, runtime modules are compiled into WebAssembly (Wasm), which is also referred to as Wasm.