Bech32m

Bech32m is a checksummed base-32 address encoding for Bitcoin-style networks, defined in BIP 350 as a revision of the bech32 format from BIP 173. An address consists of a human-readable prefix, the separator 1, and data in a 32-character alphabet protected by a checksum that detects common typing errors.

#The checksum fix

Bech32 has a mutation weakness: when the final character of an address is p, inserting or deleting q characters immediately before it does not invalidate the checksum. Bech32m changes the checksum constant from 1 to 0x2bc830a3, restoring the guarantee that small insertions and substitutions are detected.

#Usage

Bitcoin uses bech32m for segwit version 1 and later outputs, that is, taproot addresses starting with bc1p (BIP 341); version 0 addresses keep the original bech32. An address encodes the locking condition of a UTXO, and the encoding matters for quantum analysis because taproot outputs expose a public key directly (taproot and quantum key exposure). The BTX network also encodes its addresses with bech32m, using the prefix btx1z.