CIDv1

CIDv1 is the version 1 format of Content Identifiers (CIDs) used in the IPFS and IPLD ecosystems. A CID is a self-describing, content-addressed pointer that encodes how to retrieve content and how that content is structured. CIDv1 expands the addressing system beyond the original CIDv0 design, providing greater flexibility and future-proofing.

A CIDv1 has three components: the version field (set to 1), the codec or multicodec that identifies the data format of the content, and the multihash that specifies the hash function and the digest. In binary form the CID is a sequence of varints; when displayed as text, it is encoded with a multibase. The most common user-facing textual form is base32, which typically yields strings that start with prefixes like bafy or similar, depending on the chosen multicodec and hash function.

CIDv1 is designed to be future-proof and extensible. It can express multiple codecs (for example different IPLD data formats) and multiple hash algorithms (such as sha2-256, sha3-256, blake2b-256, etc.). This flexibility allows new data types and hashing methods to be adopted without changing the underlying addressing mechanism. CIDv0 remains in use for compatibility: it is a special case with a specific codec and hash function (and is usually represented in base58btc). In practice, many systems can convert between CIDv0 and CIDv1 to preserve links and interoperability.

Usage and adoption: CIDv1 is a core component of IPFS addressing and is supported by libraries across numerous programming languages. It enables links to content that may use different formats and hash algorithms while remaining globally addressable. See also: Content Identifier, Multiformats, Multihash, Multicodec, IPFS, IPLD.