# Copyright (c) 2026 Emanuele Bellocchia
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# THE SOFTWARE.
"""Module for Nano address encoding/decoding."""
# Imports
from typing import Any, Union
from typing_extensions import override
from bip_utils.addr.addr_dec_utils import AddrDecUtils
from bip_utils.addr.addr_key_validator import AddrKeyValidator
from bip_utils.addr.iaddr_decoder import IAddrDecoder
from bip_utils.addr.iaddr_encoder import IAddrEncoder
from bip_utils.coin_conf import CoinsConf
from bip_utils.ecc import Ed25519Blake2bPublicKey, IPublicKey
from bip_utils.utils.crypto import Blake2b40
from bip_utils.utils.misc import Base32Decoder, Base32Encoder, BytesUtils
class NanoAddrConst:
"""Class container for Nano address constants."""
# Alphabet for base32
BASE32_ALPHABET: str = "13456789abcdefghijkmnopqrstuwxyz"
# Payload padding (decoded)
PAYLOAD_PAD_DEC: bytes = b"\x00\x00\x00"
# Payload padding (encoded)
PAYLOAD_PAD_ENC: str = "1111"
class _NanoAddrUtils:
"""Nano address utility class."""
@staticmethod
def ComputeChecksum(pub_key_bytes: bytes) -> bytes:
"""
Compute checksum in Nano format.
Args:
pub_key_bytes (bytes): Public key bytes
Returns:
bytes: Computed checksum
"""
return BytesUtils.Reverse(Blake2b40.QuickDigest(pub_key_bytes))
class NanoAddrDecoder(IAddrDecoder):
"""
Nano address decoder class.
It allows the Nano address decoding.
"""
@override
@staticmethod
def DecodeAddr(addr: str,
**kwargs: Any) -> bytes:
"""
Decode a Nano address to bytes.
Args:
addr (str): Address string
**kwargs : Not used
Returns:
bytes: Public key bytes
Raises:
ValueError: If the address encoding is not valid
"""
# Validate and remove prefix
addr_no_prefix = AddrDecUtils.ValidateAndRemovePrefix(addr,
CoinsConf.Nano.ParamByKey("addr_prefix"))
# Decode from base32
addr_dec_bytes = Base32Decoder.Decode(NanoAddrConst.PAYLOAD_PAD_ENC + addr_no_prefix,
NanoAddrConst.BASE32_ALPHABET)
# Validate length
AddrDecUtils.ValidateLength(addr_dec_bytes,
Ed25519Blake2bPublicKey.CompressedLength() + Blake2b40.DigestSize()
+ len(NanoAddrConst.PAYLOAD_PAD_DEC) - 1)
# Get back checksum and public key bytes
pub_key_bytes, checksum_bytes = AddrDecUtils.SplitPartsByChecksum(
addr_dec_bytes[len(NanoAddrConst.PAYLOAD_PAD_DEC):],
Blake2b40.DigestSize()
)
# Validate checksum
AddrDecUtils.ValidateChecksum(pub_key_bytes, checksum_bytes, _NanoAddrUtils.ComputeChecksum)
# Validate public key
AddrDecUtils.ValidatePubKey(pub_key_bytes, Ed25519Blake2bPublicKey)
return pub_key_bytes
class NanoAddrEncoder(IAddrEncoder):
"""
Nano address encoder class.
It allows the Nano address encoding.
"""
@override
@staticmethod
def EncodeKey(pub_key: Union[bytes, IPublicKey],
**kwargs: Any) -> str:
"""
Encode a public key to Nano address.
Args:
pub_key (bytes or IPublicKey): Public key bytes or object
**kwargs: Not used
Returns:
str: Address string
Raises:
ValueError: If the public key is not valid
TypeError: If the public key is not ed25519-blake2b
"""
pub_key_obj = AddrKeyValidator.ValidateAndGetEd25519Blake2bKey(pub_key)
pub_key_bytes = pub_key_obj.RawCompressed().ToBytes()[1:]
# Compute checksum
checksum_bytes = _NanoAddrUtils.ComputeChecksum(pub_key_bytes)
# Encode to base32
payload_bytes = NanoAddrConst.PAYLOAD_PAD_DEC + pub_key_bytes + checksum_bytes
b32_enc = Base32Encoder.EncodeNoPadding(payload_bytes, NanoAddrConst.BASE32_ALPHABET)
# Add prefix
return CoinsConf.Nano.ParamByKey("addr_prefix") + b32_enc[len(NanoAddrConst.PAYLOAD_PAD_ENC):]
# Deprecated: only for compatibility, Encoder class shall be used instead
NanoAddr = NanoAddrEncoder