Base58Check

Base58Check adds a 4-byte double-SHA256 checksum to Base58 encoding. Used for legacy Bitcoin addresses (1... and 3...), WIF private keys, and extended keys. The version byte identifies the type: 0x00 for P2PKH addresses, 0x05 for P2SH, 0x80 for WIF keys. Decoding validates the checksum to detect transcription errors.