# Copyright (c) 2026 Emanuele Bellocchia
#
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"""
Module for BIP39 mnemonic encoding.
Reference: https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki
"""
# Imports
from typing_extensions import override
from bip_utils.bip.bip39.bip39_entropy_generator import Bip39EntropyGenerator
from bip_utils.bip.bip39.bip39_mnemonic import Bip39Languages, Bip39Mnemonic, Bip39MnemonicConst
from bip_utils.bip.bip39.bip39_mnemonic_utils import Bip39WordsListGetter
from bip_utils.utils.crypto import Sha256
from bip_utils.utils.misc import BytesUtils, IntegerUtils
from bip_utils.utils.mnemonic import Mnemonic, MnemonicEncoderBase
class Bip39MnemonicEncoder(MnemonicEncoderBase):
"""
BIP39 mnemonic encoder class.
It encodes bytes to the mnemonic phrase.
"""
def __init__(self,
lang: Bip39Languages = Bip39Languages.ENGLISH) -> None:
"""
Construct class.
Args:
lang (Bip39Languages, optional): Language (default: English)
Raises:
TypeError: If the language is not a Bip39Languages enum
ValueError: If loaded words list is not valid
"""
super().__init__(lang, Bip39WordsListGetter)
@override
def Encode(self,
entropy_bytes: bytes) -> Mnemonic:
"""
Encode bytes to mnemonic phrase.
Args:
entropy_bytes (bytes): Entropy bytes (accepted lengths in bits: 128, 160, 192, 224, 256)
Returns:
Mnemonic object: Encoded mnemonic
Raises:
ValueError: If entropy is not valid
"""
# Check entropy length
entropy_byte_len = len(entropy_bytes)
if not Bip39EntropyGenerator.IsValidEntropyByteLen(entropy_byte_len):
raise ValueError(f"Entropy byte length ({entropy_byte_len}) is not valid")
# Convert entropy to binary string
entropy_bin_str = BytesUtils.ToBinaryStr(entropy_bytes, entropy_byte_len * 8)
# Get entropy hash as binary string
entropy_hash_bin_str = BytesUtils.ToBinaryStr(Sha256.QuickDigest(entropy_bytes),
Sha256.DigestSize() * 8)
# Get mnemonic binary string by concatenating entropy and checksum
mnemonic_bin_str = entropy_bin_str + entropy_hash_bin_str[:entropy_byte_len // 4]
# Get mnemonic from entropy
mnemonic = []
for i in range(len(mnemonic_bin_str) // Bip39MnemonicConst.WORD_BIT_LEN):
# Get current word index
word_bin_str = (mnemonic_bin_str[i * Bip39MnemonicConst.WORD_BIT_LEN:(i + 1)
* Bip39MnemonicConst.WORD_BIT_LEN])
word_idx = IntegerUtils.FromBinaryStr(word_bin_str)
# Get word at given index
mnemonic.append(self.m_words_list.GetWordAtIdx(word_idx))
return Bip39Mnemonic.FromList(mnemonic)