CIDv1 base32 encoding

Question

Can anyone help me understand how string version is calculated for CIDv1?

Example: bafykbzacea6h5nvlblvak5jhj7m7ku5sp7u2roo3lbembab3a6tnvmuzgcqas

Is this right hex representation according to CID explorer 0170B220203C7EB6AB0AEA0575274FD9F553B27FE9A8B9DB5848C0803B07A6DAB29930A009

Using this tool, values doesn't match.

Answer 1

The hex displayed by the CID explorer shows the HEX of the hash DIGEST part, not the entire CID. This enables you to extract raw blake2b-256 from the CID.

CIDv1 have a prefix which for your CID is:

• multibase-indicator: b (base23) (which informs how to decode binary bytes that follow)
• cid version: 1
• multicodec-content-type: dag-pb
• multihash, which itself has three fields
  • code of the hash function used: blake2b-256
  • length of digest: 32
  • DIGEST

Relevant docs:

• https://github.com/multiformats/cid#how-does-it-work
• https://github.com/multiformats/multihash
• https://github.com/multiformats/multicodec/blob/master/table.csv → "code" column lists numeric value (in hex) for names like dag-pb etc

To inspect CID details like prefix (things before hash digest) with ipfs cid format (from Kubo):

$ ipfs cid format -f "(%b)-(%v)-(%c)-(%h)-(%L)-DIGEST" bafykbzacea6h5nvlblvak5jhj7m7ku5sp7u2roo3lbembab3a6tnvmuzgcqas
(base32)-(cidv1)-(dag-pb)-(blake2b-256)-(32)-DIGEST

See ipfs cid format --help.