How to detect multibase of a CID - Githubissues

dwyl / cid

❄️cid ("content id") is a human-friendly (readable/typeable) unique ID function built for distributed/decentralised systems.

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How to detect multibase of a CID #15

Open SimonLab opened 5 years ago

SimonLab commented 5 years ago

Given a CID the first step when decoding the CID is to determine which multibase is used see https://github.com/multiformats/multibase

The CID(v1) encode this information on the first byte (ie the first 8 bits), see https://github.com/multiformats/cid#decoding-algorithm where:

So the first step is to extract the first byte and to get a representation in hexadecimal. Then we can match with the multibase table to determine which encoding is used (the 0x is an indication to tell us that the text is in base16 which is hexadecimal)

[ ] Check the implementations of multibase to know how the first byte is extracted see https://github.com/multiformats/js-multibase

SimonLab commented 5 years ago

Knowing the encoding is in fact simple.

Get the first byte/letter
match this first letter with the multibase table with the code column
check the encoding column

see