ipfs-cid
A library for building IPFS CID v1 compatible content identifiers using fixed encoding parameters.
Usage
Get CID from bytes
All at once
from ipfs_cid import cid_sha256_hash
data = b"Hello world"
result = cid_sha256_hash(data)
assert result == "bafkreide5semuafsnds3ugrvm6fbwuyw2ijpj43gwjdxemstjkfozi37hq"In chunks with a generator
from typing import Iterable
from io import BytesIO
from ipfs_cid import cid_sha256_hash_chunked
def as_chunks(stream: BytesIO, chunk_size: int) -> Iterable[bytes]:
while len((chunk := stream.read(chunk_size))) > 0:
yield chunk
buffer = BytesIO(b"Hello world")
result = cid_sha256_hash_chunked(as_chunks(buffer, 4))
assert result == "bafkreide5semuafsnds3ugrvm6fbwuyw2ijpj43gwjdxemstjkfozi37hq"Wrap an existing SHA 256 checksum as a CID
WARNING: This will lead to an invalid CID if an invalid digest is provided. This is not possible to validate against without the original data.
from hashlib import sha256
from ipfs_cid import cid_sha256_wrap_digest
data = b"Hello world"
digest = sha256(data).digest()
result = cid_sha256_wrap_digest(digest)
assert result == "bafkreide5semuafsnds3ugrvm6fbwuyw2ijpj43gwjdxemstjkfozi37hq"Unwrap a compatible CID to a sha256 digest
NOTE: The cid_sha256_unwrap_digest function will throw an AttributeError
if the input CID is not using the same encoding parameters.
from hashlib import sha256
from ipfs_cid import cid_sha256_unwrap_digest
data = b"Hello world"
digest = sha256(data).digest()
cid = "bafkreide5semuafsnds3ugrvm6fbwuyw2ijpj43gwjdxemstjkfozi37hq"
result = cid_sha256_unwrap_digest(cid)
assert result == digestEncoding Format
The CID spec supports multiple different encodings and hashing algorithms.
The resulting CID string is composed of the following components:
{multibase prefix} + multibase_encoded({cid version} + {content type} + {multihash})
This library always uses the following encoding parameters:
| multibase | CID version | Content Type | Multihash |
|---|---|---|---|
| base32 | cidv1 | raw | sha2-256 |
More details about the formats below:
Multibase
| encoding | code | description |
|---|---|---|
| base32 | b | rfc4648 case-insensitive - no padding |
Multicodec
| name | code | description |
|---|---|---|
| cidv1 | 0x01 | CID v1 |
| sha2-256 | 0x12 | sha2-256 with 256 bit digest |
| raw | 0x55 | raw binary |
