By identityfoundry.com
Multicodec is part of the Multiformats collection of protocols. Multiformats is a collection of protocols which aim to future-proof systems, today. They do this mainly by allowing data to be self-describable. See:
The Multicodec is an agreed way for encoding bytes with a prefix that specifies the type of encoding. The format is therefore a portable and self describing way of expressing an encoding of bytes that does not assume a specific context. See:
For example, the multicodec specification is used in the specifications for Decentralised Identifiers (DIDs) in regard to the DID Method 'key' specification. Therefore, any work on did:key implementations needs to also solve for the use of multicodecs. See:
It is noted that the https://github.com/multiformats/multiformats lists technology implementations, however a java implementation is not available. This library addresses that gap to provide an implementation of the multicodec specification in java.
The code of a multicodec is encoded as unsigned varint as defined by multiformats/unsigned-varint. It is then used as a prefix to identify the data that follows. This represents some additional binary operations.
This project also solves for a java implementation of unsigned varints so may also be of use for implementors.
//Demonstrate the encoding of data for an example ED25519 public key...
byte[] raw = getEd25519PublicKeyData();
byte[] multicodecEncoding = Multicodec.encode(Multicodec.Codec.ED25519_PUB, raw);
//Demonstrate the decoding...
DecodedData decodedData = null;
try {
decodedData = MulticodecEncoder.decode(multicodecEncoding);
} catch (AmbiguousCodecEncodingException exAmbiguousCodecEncoding) {
System.err.println("AmbiguousCodecEncodingException:" + exAmbiguousCodecEncoding.getMessage());
}
if (decodedData != null) {
System.out.printf("Codec:%s(%s)%n", decodedData.getCodec().name(), decodedData.getCodec().code);
System.out.println("byte data length:" + decodedData.getDataAsBytes().length);
System.out.println("hex data:" + decodedData.getDataAsHex());
}
There are two basic classes of the codecs, single bytes codes (e.g cidv1(0x01), sha2_256(0x12)) and multibyte codecs (e.g. upd(0x0111), p256_pub(0x1200)).
The way that the codec codes are configured it is possible to encode to them, but there are situations where it is not possible to decode.
0xA1E9D3D8ECcidv1 encoded we have : 0xA1E9D3D8EC --(cidv1)--> 0x01A1E9D3D8ECupd encoded we have : 0xA1E9D3D8EC --(upd)----> 0x0111A1E9D3D8EC0x01.udp value 0x0111A1E9D3D8EC it is not possible to determine if the string is
cidv1 encoded with data: 0x11A1E9D3D8ECupd encoded with data: 0xA1E9D3D8ECAnother example also applies to sha2_256 and p256_pub encoding.
sha2_256 encoded we have : 0xA1E9D3D8EC --(sha2_256)--> 0x12A1E9D3D8ECp256_pub encoded we have : 0xA1E9D3D8EC --(p256_pub)--> 0x1200A1E9D3D8EC0x12.p256_pub value 0x1200A1E9D3D8EC it is not possible to determine if the string is
sha2_256 encoded with data: 0x00A1E9D3D8ECp256_pub encoded with data: 0x1200A1E9D3D8ECThese clashes occur in a number of situations and are listed below.
'Clash of codecs' spec problem: cannot decode between [UDP(0x0111)], and [CIDV1(0x01)] for sample data:[0111A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P2P_WEBRTC_STAR(0x0113)], and [CIDV1(0x01)] for sample data:[0113A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P2P_WEBRTC_DIRECT(0x0114)], and [CIDV1(0x01)] for sample data:[0114A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P2P_STARDUST(0x0115)], and [CIDV1(0x01)] for sample data:[0115A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [WEBRTC(0x0118)], and [CIDV1(0x01)] for sample data:[0118A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P2P_CIRCUIT(0x0122)], and [CIDV1(0x01)] for sample data:[0122A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [DAG_JSON(0x0129)], and [CIDV1(0x01)] for sample data:[0129A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [UDT(0x012D)], and [CIDV1(0x01)] for sample data:[012DA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [UTP(0x012E)], and [CIDV1(0x01)] for sample data:[012EA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [UNIX(0x0190)], and [CIDV1(0x01)] for sample data:[019001A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [THREAD(0x0196)], and [CIDV1(0x01)] for sample data:[019601A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P2P(0x01A5)], and [CIDV1(0x01)] for sample data:[01A501A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [IPFS(0x01A5)], and [CIDV1(0x01)] for sample data:[01A501A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [HTTPS(0x01BB)], and [CIDV1(0x01)] for sample data:[01BB01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [ONION(0x01BC)], and [CIDV1(0x01)] for sample data:[01BC01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [ONION3(0x01BD)], and [CIDV1(0x01)] for sample data:[01BD01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [GARLIC64(0x01BE)], and [CIDV1(0x01)] for sample data:[01BE01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [GARLIC32(0x01BF)], and [CIDV1(0x01)] for sample data:[01BF01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [TLS(0x01C0)], and [CIDV1(0x01)] for sample data:[01C001A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [NOISE(0x01C6)], and [CIDV1(0x01)] for sample data:[01C601A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [QUIC(0x01CC)], and [CIDV1(0x01)] for sample data:[01CC01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [WEBTRANSPORT(0x01D1)], and [CIDV1(0x01)] for sample data:[01D101A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [CERTHASH(0x01D2)], and [CIDV1(0x01)] for sample data:[01D201A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [WS(0x01DD)], and [CIDV1(0x01)] for sample data:[01DD01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [WSS(0x01DE)], and [CIDV1(0x01)] for sample data:[01DE01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P2P_WEBSOCKET_STAR(0x01DF)], and [CIDV1(0x01)] for sample data:[01DF01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [HTTP(0x01E0)], and [CIDV1(0x01)] for sample data:[01E001A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [SWHID_1_SNP(0x01F0)], and [CIDV1(0x01)] for sample data:[01F001A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [JSON(0x0200)], and [CIDV2(0x02)] for sample data:[0200A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [MESSAGEPACK(0x0201)], and [CIDV2(0x02)] for sample data:[0201A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [CAR(0x0202)], and [CIDV2(0x02)] for sample data:[0202A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [LIBP2P_PEER_RECORD(0x0301)], and [CIDV3(0x03)] for sample data:[0301A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [LIBP2P_RELAY_RSVP(0x0302)], and [CIDV3(0x03)] for sample data:[0302A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [CAR_INDEX_SORTED(0x0400)], and [IP4(0x04)] for sample data:[0400A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [CAR_MULTIHASH_INDEX_SORTED(0x0401)], and [IP4(0x04)] for sample data:[0401A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [X11(0x1100)], and [SHA1(0x11)] for sample data:[1100A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P256_PUB(0x1200)], and [SHA2_256(0x12)] for sample data:[1200A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P384_PUB(0x1201)], and [SHA2_256(0x12)] for sample data:[1201A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [P521_PUB(0x1202)], and [SHA2_256(0x12)] for sample data:[1202A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [ED448_PUB(0x1203)], and [SHA2_256(0x12)] for sample data:[1203A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [X448_PUB(0x1204)], and [SHA2_256(0x12)] for sample data:[1204A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [RSA_PUB(0x1205)], and [SHA2_256(0x12)] for sample data:[1205A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [SM2_PUB(0x1206)], and [SHA2_256(0x12)] for sample data:[1206A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [ED25519_PRIV(0x1300)], and [SHA2_512(0x13)] for sample data:[1300A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [SECP256K1_PRIV(0x1301)], and [SHA2_512(0x13)] for sample data:[1301A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [X25519_PRIV(0x1302)], and [SHA2_512(0x13)] for sample data:[1302A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [KANGAROOTWELVE(0x1D01)], and [KECCAK_512(0x1D)] for sample data:[1D01A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_8(0xB201)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20101A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_16(0xB202)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20102A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_24(0xB203)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20103A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_32(0xB204)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20104A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_40(0xB205)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20105A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_48(0xB206)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20106A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_56(0xB207)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20107A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_64(0xB208)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20108A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_72(0xB209)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20109A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_80(0xB20A)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2010AA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_88(0xB20B)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2010BA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_96(0xB20C)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2010CA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_104(0xB20D)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2010DA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_112(0xB20E)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2010EA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_120(0xB20F)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2010FA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_128(0xB210)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20110A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_136(0xB211)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20111A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_144(0xB212)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20112A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_152(0xB213)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20113A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_160(0xB214)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20114A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_168(0xB215)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20115A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_176(0xB216)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20116A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_184(0xB217)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20117A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_192(0xB218)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20118A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_200(0xB219)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20119A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_208(0xB21A)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2011AA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_216(0xB21B)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2011BA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_224(0xB21C)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2011CA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_232(0xB21D)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2011DA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_240(0xB21E)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2011EA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_248(0xB21F)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2011FA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_256(0xB220)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20120A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_264(0xB221)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20121A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_272(0xB222)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20122A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_280(0xB223)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20123A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_288(0xB224)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20124A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_296(0xB225)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20125A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_304(0xB226)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20126A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_312(0xB227)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20127A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_320(0xB228)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20128A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_328(0xB229)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20129A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_336(0xB22A)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2012AA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_344(0xB22B)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2012BA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_352(0xB22C)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2012CA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_360(0xB22D)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2012DA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_368(0xB22E)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2012EA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_376(0xB22F)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2012FA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_384(0xB230)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20130A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_392(0xB231)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20131A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_400(0xB232)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20132A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_408(0xB233)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20133A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_416(0xB234)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20134A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_424(0xB235)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20135A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_432(0xB236)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20136A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_440(0xB237)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20137A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_448(0xB238)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20138A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_456(0xB239)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20139A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_464(0xB23A)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2013AA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_472(0xB23B)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2013BA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_480(0xB23C)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2013CA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_488(0xB23D)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2013DA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_496(0xB23E)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2013EA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_504(0xB23F)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2013FA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2B_512(0xB240)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20140A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_8(0xB241)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20141A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_16(0xB242)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20142A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_24(0xB243)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20143A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_32(0xB244)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20144A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_40(0xB245)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20145A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_48(0xB246)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20146A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_56(0xB247)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20147A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_64(0xB248)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20148A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_72(0xB249)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20149A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_80(0xB24A)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2014AA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_88(0xB24B)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2014BA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_96(0xB24C)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2014CA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_104(0xB24D)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2014DA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_112(0xB24E)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2014EA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_120(0xB24F)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B2014FA1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_128(0xB250)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20150A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_136(0xB251)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20151A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_144(0xB252)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20152A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_152(0xB253)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20153A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_160(0xB254)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20154A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_168(0xB255)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20155A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_176(0xB256)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20156A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_184(0xB257)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20157A1E9D3D8EC] because codes start with the same values. 'Clash of codecs' spec problem: cannot decode between [BLAKE2S_192(0xB258)], and [BITCOIN_WITNESS_COMMITMENT(0xB2)] for sample data:[B20158A1E9D3D8EC] because codes start with the same values.
The Multicodec.decode() method makes the assumption that the decoding only supports single byte codec codes, to prevent the "clash of codecs" issue from presenting itself. This means that while Multicodec.encode() method can encode for any codec code, the Multicodec.decode() does not support decoding of multibyte codec codes.
If Multicodec.decode() is used to decode a multibyte codec code then AmbiguousCodecEncodingException is thrown.
The bytes used in the codec prefix need to be unambiguous. Pick a used reserved byte (e.g. 0x00) and use as a delimiter between the codec code bytes and the data
cidv1 0x01 0x00 0xA1E9D3D8EC 0x0100A1E9D3D8EC 0x [0100] [A1E9D3D8EC] -> cidv1 upd 0x0111 0x00 0xA1E9D3D8EC 0x011100A1E9D3D8EC 0x [011100] [A1E9D3D8EC] -> udp
0x00), which is an implicit rule that is too easily broken for new codec additions.0x00) must be reassigned to a value that does not. e.g. p256_pub(0x1200) must be reassigned.The bytes used in the codec prefix need to be unambiguous. The multibyte codec values that are in draft need to be re-assigned so there is no possible clashes.
The bytes used in the codec prefix need to be unambiguous.
0x00)0x00).0x00).cidv1 0x01 n/a 0xA1E9D3D8EC 0x01A1E9D3D8EC 0x [01] [A1E9D3D8EC] -> cidv1 sha2_256 0x12 n/a 0xA1E9D3D8EC 0x12A1E9D3D8EC 0x [12] [A1E9D3D8EC] -> sha2_256 upd 0x0111 0x00 0xA1E9D3D8EC 0x00011100A1E9D3D8EC 0x [00] [0111] [00] [A1E9D3D8EC] -> udp p256_pub 0x1200 0x00 0xA1E9D3D8EC 0x00120000A1E9D3D8EC 0x [00] [1200] [00] [A1E9D3D8EC] -> p256_pub
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