return ECPubkey._from_libsecp256k1_pubkey_ptr(pubkey) CURVE_O | 🎩BLACK HAT🎩

return ECPubkey._from_libsecp256k1_pubkey_ptr(pubkey)

CURVE_ORDER = 0xFFFFFFFF_FFFFFFFF_FFFFFFFF_FFFFFFFE_BAAEDCE6_AF48A03B_BFD25E8C_D0364141
GENERATOR = ECPubkey(bytes.fromhex('0479be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798'
'483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8'))
POINT_AT_INFINITY = ECPubkey(None)

class ECPrivkey(ECPubkey):
def __init__(self, privkey_bytes: bytes):

assert_bytes(privkey_bytes)
if len(privkey_bytes) != 32:
raise Exception('unexpected size for secret. should be 32 bytes, not {}'.format(len(privkey_bytes)))

secret = string_to_number(privkey_bytes)

if not is_secret_within_curve_range(secret):
raise InvalidECPointException('Invalid secret scalar (not within curve order)')
self.secret_scalar = secret

pubkey = GENERATOR * secret

super().__init__(pubkey.get_public_key_bytes(compressed=False))

@classmethod
def from_arbitrary_size_secret(cls, privkey_bytes: bytes):
return ECPrivkey(cls.normalize_secret_bytes(privkey_bytes))

@classmethod
def normalize_secret_bytes(cls, privkey_bytes: bytes) -> bytes:
scalar = string_to_number(privkey_bytes) % CURVE_ORDER
if scalar == 0:
raise Exception('invalid EC private key scalar: zero')
privkey_32bytes = int.to_bytes(scalar, length=32, byteorder='big', signed=False)
return privkey_32bytes

def decrypt_message(self, encrypted: Union[str, bytes], magic: bytes=b'BIE1') -> bytes:

encrypted = base64.b64decode(encrypted)
if len(encrypted) < 85:
return False

magic_found = encrypted[:4]
ephemeral_pubkey_bytes = encrypted[4:37]
ciphertext = encrypted[37:-32]
mac = encrypted[-32:]
if magic_found != magic:
return False
try:
ephemeral_pubkey = ECPubkey(ephemeral_pubkey_bytes)
except:
return False

ecdh_key = (ephemeral_pubkey * self.secret_scalar).get_public_key_bytes(compressed=True)
key = hashlib.sha512(ecdh_key).digest()
iv, key_e, key_m = key[0:16], key[16:32], key[32:]

if mac != hmac_oneshot(key_m, encrypted[:-32], hashlib.sha256):
return False
else:
return True


Public key creation starts with

pubkey = GENERATOR * secret


The GENERATOR variable is ECPubkey(bytes.fromhex('...')). those. prototype of the ECPubkey class. To multiply ECPubkey by int, you need to consider the presence of a method mul (multiplication)in the ECPubkey class.

Now let's analyze the long-awaited decrypt_message () method, which is called in main.pyand should return us the result. At this point, it's worth noting that we have already initialized the ECPubkey and ECPrivkey classes earlier (keep that in mind)

def decrypt_message(self, encrypted: Union[str, bytes], magic: bytes=b'BIE1') -> bytes:

encrypted = base64.b64decode(encrypted)
if len(encrypted) < 85:
return False

magic_found = encrypted[:4]
ephemeral_pubkey_bytes = encrypted[4:37]
ciphertext = encrypted[37:-32]
mac = encrypted[-32:]
if magic_found != magic:
return False

try:
ephemeral_pubkey = ECPubkey(ephemeral_pubkey_bytes)
except:
return False

ecdh_key = (ephemeral_pubkey * self.secret_scalar).get_public_key_bytes(compressed=True)
key = hashlib.sha512(ecdh_key).digest()
iv, key_e, key_m = key[0:16], key[16:32], key[32:]

# здесь мы оставим только return False если пароль не соответствует искомому и return False в противном случае.
if mac != hmac_oneshot(key_m, encrypted[:-32], hashlib.sha256):
return False
else:
return True