def __DecryptAndGetFactorb(encrypted_part_1_lower: bytes,
encrypted_part_2: bytes,
derived_half_1: bytes,
derived_half_2: bytes) -> bytes:
"""
Decrypt and get back factorb.
Args:
encrypted_part_1_lower (bytes): Lower part of first encrypted part
encrypted_part_2 (bytes) : Second encrypted part
derived_half_1 (bytes) : First half of derived key
derived_half_2 (bytes) : Second half of derived key
Returns:
bytes: Factorb
"""
# Use derived_half_2 as AES key
aes_dec = AesEcbDecrypter(derived_half_2)
aes_dec.AutoUnPad(False)
# Decrypt the second part and get back the higher parts of seedb and encrypted half 1
decrypted_part_2 = BytesUtils.Xor(aes_dec.Decrypt(encrypted_part_2), derived_half_1[16:])
encrypted_part_1_higher = decrypted_part_2[:8]
seedb_part_2 = decrypted_part_2[8:]
# Decrypt the first part to get the lower part of seedb
seedb_part_1 = BytesUtils.Xor(aes_dec.Decrypt(encrypted_part_1_lower + encrypted_part_1_higher),
derived_half_1[:16])
# Rebuild the complete seedb
seedb = seedb_part_1 + seedb_part_2
# Compute factorb from seedb
return CryptoUtils.DoubleSha256(seedb)
def __EncryptSeedb(seedb: bytes,
derived_half_1: bytes,
derived_half_2: bytes) -> Tuple[bytes, bytes]:
"""
Encrypt seedb in two parts.
Args:
seedb (bytes) : Seedb
derived_half_1 (bytes): First half of derived key
derived_half_2 (bytes): Second half of derived key
Returns:
tuple[bytes, bytes]: Two encrypted parts
"""
# Use derived_half_2 as AES key
aes_enc = AesEcbEncrypter(derived_half_2)
aes_enc.AutoPad(False)
# Encrypt the first part: seedb[0...15] xor derived_half_1[0...15]
encrypted_part_1 = aes_enc.Encrypt(BytesUtils.Xor(seedb[:16], derived_half_1[:16]))
# Encrypt the second part: (encrypted_part_1[8...15] + seedb[16...23])) xor derivedhalf1[16...31]
encrypted_part_2 = aes_enc.Encrypt(BytesUtils.Xor(encrypted_part_1[8:] + seedb[16:], derived_half_1[16:]))
return encrypted_part_1, encrypted_part_2
def __EncryptPrivateKey(priv_key_bytes: bytes, derived_half_1: bytes,
derived_half_2: bytes) -> Tuple[bytes, bytes]:
"""
Encrypt private key in two halves.
Args:
priv_key_bytes (bytes): Private key
derived_half_1 (bytes): First half of derived key
derived_half_2 (bytes): Second half of derived key
Returns:
tuple[bytes, bytes]: Two encrypted halves
"""
# Use derived_half_2 as AES key
aes_enc = AesEcbEncrypter(derived_half_2)
aes_enc.AutoPad(False)
# Encrypt the first half: priv_key[0...15] xor derived_half_1[0...15]
encrypted_half_1 = aes_enc.Encrypt(
BytesUtils.Xor(priv_key_bytes[:16], derived_half_1[:16]))
# Encrypt the second half: priv_key[16...31] xor derived_half_1[16...31]
encrypted_half_2 = aes_enc.Encrypt(
BytesUtils.Xor(priv_key_bytes[16:], derived_half_1[16:]))
return encrypted_half_1, encrypted_half_2
def __DecryptAndGetPrivKey(encrypted_half_1: bytes,
encrypted_half_2: bytes, derived_half_1: bytes,
derived_half_2: bytes) -> bytes:
"""
Decrypt and get back private key.
Args:
encrypted_half_1 (bytes): First encrypted half
encrypted_half_2 (bytes): Second encrypted half
derived_half_1 (bytes) : First half of derived key
derived_half_2 (bytes) : Second half of derived key
Returns:
bytes: Decrypted private key
"""
# Use derived_half_2 as AES key
aes_dec = AesEcbDecrypter(derived_half_2)
aes_dec.AutoUnPad(False)
# Decrypt using AES256Decrypt
decrypted_half_1 = aes_dec.Decrypt(encrypted_half_1)
decrypted_half_2 = aes_dec.Decrypt(encrypted_half_2)
# Get the private key back by XORing bytes
return BytesUtils.Xor(decrypted_half_1 + decrypted_half_2,
derived_half_1)
