CID class

A Content Identifier (CID) for content-addressed data in IPFS.

CIDs are self-describing content addresses used to uniquely identify data in IPFS and other distributed systems. They combine a cryptographic hash of the content with metadata about the hashing algorithm and data encoding format.

IPFS supports two CID versions:

  • CIDv0: Legacy format, always SHA2-256 + DAG-PB, base58btc encoded
  • CIDv1: Modern format with flexible codecs and multibase encoding

Example:

// Create CID from content
final data = Uint8List.fromList(utf8.encode('Hello IPFS'));
final cid = await CID.fromContent(data);
// print('CID: ${cid.encode()}');  // bafkreif...

// Decode existing CID
final decoded = CID.decode('QmYwAPJzv5CZsnA...');
// print('Version: ${decoded.version}');

See also:

Constructors

CID({required int version, required MultihashInfo multihash, String? codec, Multibase? multibaseType})
Creates a CID with the specified components.
const
CID.v0(Uint8List hashBytes)
Creates a CIDv0. CIDv0 is always: SHA2-256, DAG-PB, Base58BTC.
factory
CID.v1(String codec, MultihashInfo multihash, {Multibase base = Multibase.base32})
Creates a CIDv1.
factory

Properties

codec → String?
The content codec (e.g., 'dag-pb', 'raw', 'dag-cbor').
final
hashCode → int
The hash code for this object.
no setteroverride
multibaseType → Multibase?
The multibase encoding type for string representation.
final
multihash → MultihashInfo
The multihash containing the hash algorithm and digest.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
version → int
The CID version (0 or 1).
final

Methods

encode() → String
Encodes the CID to its string representation.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toBytes() → Uint8List
Converts the CID to its binary representation.
toProto() → IPFSCIDProto
Converts the CID to a Protobuf representation.
toString() → String
A string representation of this object.
override
validate() → bool
Validates the CID.

Operators

operator ==(Object other) → bool
The equality operator.
override

Static Methods

computeForData(Uint8List data, {String format = 'raw'}) → Future<CID>
Computes CID for data (async version for compatibility).
computeForDataSync(Uint8List data, {String codec = 'raw'}) → CID
Computes CID for data (sync version).
decode(String cidStr) → CID
Decodes a CID from its string representation.
fromBytes(Uint8List bytes) → CID
Parses a CID from its raw binary representation.
fromContent(Uint8List content, {String codec = 'raw', String hashType = 'sha2-256', int version = 1}) → Future<CID>
Creates a CID from raw content.
fromProto(IPFSCIDProto proto) → CID
Creates a CID from a Protobuf representation.