CIDv1 default encoding is base58btc instead of base32

[sumanjeet0012]

CIDv1.encode() defaults to base58btc encoding. The CID specification recommends base32 as the default encoding for CIDv1 strings. Go's Cid.String() uses base32 for CIDv1.

Problem

In cid/cid.py:

class CIDv1(BaseCID):
    def encode(self, encoding: str | None = "base58btc") -> bytes:
        return multibase.encode(encoding, self.buffer)

cid = CIDv1("dag-pb", some_hash)
str(cid)  # → "zdj7Wh..." (base58btc)

Go's implementation:

func (c Cid) String() string {
    switch c.Version() {
    case 0:
        return c.Hash().B58String()
    case 1:
        mbstr, _ := mbase.Encode(mbase.Base32, c.Bytes())
        return mbstr  // → "bafybei..." (base32)
    }
}

The CID spec says:

"The default base encoding for CIDv1 is base32 (lowercase, no padding)."

Proposed Solution

Change the default encoding to base32:

class CIDv1(BaseCID):
    def encode(self, encoding: str | None = "base32") -> bytes:
        return multibase.encode(encoding, self.buffer)

⚠️ Breaking change: This changes the output of str(cid) for all CIDv1 objects. Consider:

• Adding a deprecation warning for one release cycle
• Or documenting this as a breaking change in the changelog

Update all tests that check CIDv1 string representations.

Related

• CID spec: https://github.com/multiformats/cid
• Go implementation: go-cid cid.go String()