# Copyright (c) 2026 Emanuele Bellocchia
#
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"""
Module for SS58 decoding/encoding.
Reference: https://github.com/paritytech/substrate/wiki/External-Address-Format-(SS58)
"""
# Imports
from typing import Tuple
from bip_utils.base58 import Base58Decoder, Base58Encoder
from bip_utils.ss58.ss58_ex import SS58ChecksumError
from bip_utils.utils.crypto import Blake2b512
from bip_utils.utils.misc import BytesUtils, IntegerUtils
class SS58Const:
"""Class container for SS58 constants."""
# Max format for simple account
SIMPLE_ACCOUNT_FORMAT_MAX_VAL: int = 63
# Format maximum value
FORMAT_MAX_VAL: int = 16383
# Reserved formats
RESERVED_FORMATS: Tuple[int, int] = (46, 47)
# Data length in bytes
DATA_BYTE_LEN: int = 32
# Checksum length in bytes
CHECKSUM_BYTE_LEN: int = 2
# Checksum prefix
CHECKSUM_PREFIX: bytes = b"SS58PRE"
class _SS58Utils:
"""Class container for SS58 utility functions."""
@staticmethod
def ComputeChecksum(data_bytes: bytes) -> bytes:
"""
Compute SS58 checksum.
Args:
data_bytes (bytes): Data bytes
Returns:
bytes: Computed checksum
"""
return Blake2b512.QuickDigest(SS58Const.CHECKSUM_PREFIX + data_bytes)[:SS58Const.CHECKSUM_BYTE_LEN]
class SS58Encoder:
"""SS58 encoder class. It provides methods for encoding to SS58 format."""
@staticmethod
def Encode(data_bytes: bytes,
ss58_format: int) -> str:
"""
Encode bytes into a SS58 string.
Args:
data_bytes (bytes): Data bytes (32-byte length)
ss58_format (int) : SS58 format
Returns:
str: SS58 encoded string
Raises:
ValueError: If parameters are not valid
"""
# Check parameters
if len(data_bytes) != SS58Const.DATA_BYTE_LEN:
raise ValueError(f"Invalid data length ({len(data_bytes)})")
if ss58_format < 0 or ss58_format > SS58Const.FORMAT_MAX_VAL:
raise ValueError(f"Invalid SS58 format ({ss58_format})")
if ss58_format in SS58Const.RESERVED_FORMATS:
raise ValueError(f"Invalid SS58 format ({ss58_format})")
# Simple account
if ss58_format <= SS58Const.SIMPLE_ACCOUNT_FORMAT_MAX_VAL:
ss58_format_bytes = IntegerUtils.ToBytes(ss58_format)
# Full address
else:
# 0b00HHHHHH_MMLLLLLL -> (0b01LLLLLL, 0bHHHHHHMM)
ss58_format_bytes = bytes([
((ss58_format & 0x00FC) >> 2) | 0x0040,
(ss58_format >> 8) | ((ss58_format & 0x0003) << 6)
])
# Get payload
payload = ss58_format_bytes + data_bytes
# Compute checksum
checksum = _SS58Utils.ComputeChecksum(payload)
# Encode
return Base58Encoder.Encode(payload + checksum)
class SS58Decoder:
"""SS58 decoder class. It provides methods for decoding SS58 format."""
@staticmethod
def Decode(data_str: str) -> Tuple[int, bytes]:
"""
Decode bytes from a SS58 string.
Args:
data_str (str): Data string
Returns:
tuple[int, bytes]: SS58 format and data bytes
Raises:
SS58ChecksumError: If checksum is not valid
ValueError: If the string is not a valid SS58 format
"""
# Decode string
dec_bytes = Base58Decoder.Decode(data_str)
# Full address
if dec_bytes[0] & 0x40:
ss58_format_len = 2
ss58_format = ((dec_bytes[0] & 0x3F) << 2) | (dec_bytes[1] >> 6) | \
((dec_bytes[1] & 0x3F) << 8)
# Simple account
else:
ss58_format_len = 1
ss58_format = dec_bytes[0]
# Check format
if ss58_format in SS58Const.RESERVED_FORMATS:
raise ValueError(f"Invalid SS58 format ({ss58_format})")
# Get back data and checksum
data_bytes = dec_bytes[ss58_format_len:-SS58Const.CHECKSUM_BYTE_LEN]
checksum_bytes = dec_bytes[-SS58Const.CHECKSUM_BYTE_LEN:]
# Check data length
if len(data_bytes) != SS58Const.DATA_BYTE_LEN:
raise ValueError(f"Invalid data length ({len(data_bytes)})")
# Compute checksum
checksum_bytes_got = _SS58Utils.ComputeChecksum(dec_bytes[:-SS58Const.CHECKSUM_BYTE_LEN])
# Verify checksum
if checksum_bytes != checksum_bytes_got:
raise SS58ChecksumError(
f"Invalid checksum (expected {BytesUtils.ToHexString(checksum_bytes_got)}, "
f"got {BytesUtils.ToHexString(checksum_bytes)})"
)
return ss58_format, data_bytes