Merge pull request #94 from Jc2k/gmpy2-not-required

Avoid gmpy2 dependency

.travis.yml

@@ -4,7 +4,7 @@ python:
     - "3.6"
 before_install:
     - sudo apt-get update
-    - sudo apt-get install -y libgmp-dev libmpfr-dev libmpc-dev libffi-dev build-essential python3-pip python3-dev
+    - sudo apt-get install -y libffi-dev build-essential python3-pip python3-dev
     - pip install coveralls
 script: coverage run -m unittest -v
 after_success:

README.md

@@ -12,11 +12,11 @@ The code presented in this repository was created based on release R1 from 2017-
 
 # Installation
 
-Since the code relies on **gmpy2** for large numbers some development libraries and a compiler is required:
+The code relies on some C libraries so some development packages and a compiler are required:
 
 So for debian:
 ```bash
-apt install libgmp-dev libmpfr-dev libmpc-dev libffi-dev build-essential python3-pip python3-dev
+apt install libffi-dev build-essential python3-pip python3-dev
 ```
 
 After that use **pip3** to install the package:

homekit/accessoryserver.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 #
 import binascii
-import gmpy2
 import hashlib
 import io
 import json
@@ -970,7 +969,7 @@ def _post_pair_setup(self):
             self.log_message('Step #4 /pair-setup')
 
             # 1) use ios pub key to compute shared secret key
-            ios_pub_key = gmpy2.mpz(binascii.hexlify(d_req[1][1]), 16)
+            ios_pub_key = int.from_bytes(d_req[1][1], "big")
             server = self.server.sessions[self.session_id]['srp']
             server.set_client_public_key(ios_pub_key)
 
@@ -980,7 +979,7 @@ def _post_pair_setup(self):
             self.server.sessions[self.session_id]['session_key'] = session_key
 
             # 2) verify ios proof
-            ios_proof = gmpy2.mpz(binascii.hexlify(d_req[2][1]), 16)
+            ios_proof = int.from_bytes(d_req[2][1], "big")
             if not server.verify_clients_proof(ios_proof):
                 d_res.append((TLV.kTLVType_State,  TLV.M4, ))
                 d_res.append((TLV.kTLVType_Error, TLV.kTLVError_Authentication,))

homekit/crypto/srp.py

@@ -20,21 +20,18 @@
 Implements the Secure Remote Password (SRP) algorithm. More information can be found on
 https://tools.ietf.org/html/rfc5054. See HomeKit spec page 36 for adjustments imposed by Apple.
 """
-
 import crypt
-import gmpy2
+import math
 import hashlib
-
-import six
-import binascii
+import sys
 
 
 class Srp:
     def __init__(self):
         # generator as defined by 3072bit group of RFC 5054
-        self.g = gmpy2.mpz(int(six.b('5'), 16))
+        self.g = int(b'5', 16)
         # modulus as defined by 3072bit group of RFC 5054
-        self.n = gmpy2.mpz(int(six.b('''\
+        self.n = int(b'''\
 FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E08\
 8A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B\
 302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9\
@@ -48,7 +45,7 @@ def __init__(self):
 B3970F85A6E1E4C7ABF5AE8CDB0933D71E8C94E04A25619DCEE3D226\
 1AD2EE6BF12FFA06D98A0864D87602733EC86A64521F2B18177B200C\
 BBE117577A615D6C770988C0BAD946E208E24FA074E5AB3143DB5BFC\
-E0FD108E4B82D120A93AD2CAFFFFFFFFFFFFFFFF'''), 16))
+E0FD108E4B82D120A93AD2CAFFFFFFFFFFFFFFFF''', 16)
         # HomeKit requires SHA-512 (See page 36)
         self.h = hashlib.sha512
         self.A = None
@@ -62,21 +59,22 @@ def generate_private_key():
         """
         Static function to generate a 16 byte random key.
 
-        :return: the key as gmpy2 multi-precision integer
+        :return: the key as an integer
         """
-        return gmpy2.mpz(int(binascii.hexlify(crypt.mksalt(crypt.METHOD_SHA512)[3:].encode()), 16))
+        private_key = crypt.mksalt(crypt.METHOD_SHA512)[3:].encode()
+        return int.from_bytes(private_key, "big")
 
-    def _calculate_k(self) -> gmpy2.mpz:
+    def _calculate_k(self) -> int:
         # calculate k (see https://tools.ietf.org/html/rfc5054#section-2.5.3)
         hash_instance = self.h()
         n = Srp.to_byte_array(self.n)
         g = bytearray.fromhex((383 * '00' + '05'))  # 383 * b'0' + '5'.encode()
         hash_instance.update(n)
         hash_instance.update(g)
-        k = gmpy2.mpz(int(binascii.hexlify(hash_instance.digest()), 16))
+        k = int.from_bytes(hash_instance.digest(), "big")
         return k
 
-    def _calculate_u(self) -> gmpy2.mpz:
+    def _calculate_u(self) -> int:
         if self.A is None:
             raise RuntimeError('Client\'s public key is missing')
         if self.B is None:
@@ -86,21 +84,18 @@ def _calculate_u(self) -> gmpy2.mpz:
         B_b = Srp.to_byte_array(self.B)
         hash_instance.update(A_b)
         hash_instance.update(B_b)
-        u = gmpy2.mpz(int(binascii.hexlify(hash_instance.digest()), 16))
+        u = int.from_bytes(hash_instance.digest(), "big")
         return u
 
     def get_session_key(self) -> int:
         hash_instance = self.h()
         hash_instance.update(Srp.to_byte_array(self.get_shared_secret()))
-        hash_value = int(binascii.hexlify(hash_instance.digest()), 16)
+        hash_value = int.from_bytes(hash_instance.digest(), "big")
         return hash_value
 
     @staticmethod
     def to_byte_array(num: int) -> bytearray:
-        h = gmpy2.digits(num, 16)
-        if len(h) % 2 == 1:
-            h = '0' + h
-        return bytearray.fromhex(h)
+        return bytearray(num.to_bytes(int(math.ceil(num.bit_length() / 8)), "big"))
 
     def _calculate_x(self) -> int:
         i = (self.username + ':' + self.password).encode()
@@ -112,7 +107,7 @@ def _calculate_x(self) -> int:
         hash_instance.update(Srp.to_byte_array(self.salt))
         hash_instance.update(hash_value)
 
-        return int(binascii.hexlify(hash_instance.digest()), 16)
+        return int.from_bytes(hash_instance.digest(), "big")
 
     def get_shared_secret(self):
         raise NotImplementedError()
@@ -133,16 +128,16 @@ def __init__(self, username: str, password: str):
 
     def set_salt(self, salt):
         if isinstance(salt, bytearray):
-            self.salt = gmpy2.mpz(salt.hex(), 16)
+            self.salt = int.from_bytes(salt, "big")
         else:
             self.salt = salt
 
-    def get_public_key(self) -> gmpy2.mpz:
+    def get_public_key(self):
         return pow(self.g, self.a, self.n)
 
     def set_server_public_key(self, B):
         if isinstance(B, bytearray):
-            self.B = gmpy2.mpz(B.hex(), 16)
+            self.B = int.from_bytes(B, "big")
         else:
             self.B = B
 
@@ -185,19 +180,18 @@ def get_proof(self):
         hash_instance.update(Srp.to_byte_array(self.A))
         hash_instance.update(Srp.to_byte_array(self.B))
         hash_instance.update(K)
-        r = binascii.hexlify(hash_instance.digest())
-        return int(r, 16)
+        return int.from_bytes(hash_instance.digest(), "big")
 
     def verify_servers_proof(self, M):
         if isinstance(M, bytearray):
-            tmp = gmpy2.mpz(M.hex(), 16)
+            tmp = int.from_bytes(M, "big")
         else:
             tmp = M
         hash_instance = self.h()
         hash_instance.update(Srp.to_byte_array(self.A))
         hash_instance.update(Srp.to_byte_array(self.get_proof()))
         hash_instance.update(Srp.to_byte_array(self.get_session_key()))
-        return tmp == gmpy2.mpz(binascii.hexlify(hash_instance.digest()), 16)
+        return tmp == int.from_bytes(hash_instance.digest(), "big")
 
 
 class SrpServer(Srp):
@@ -217,14 +211,12 @@ def __init__(self, username, password):
         self.A = None
 
     @staticmethod
-    def _create_salt() -> gmpy2.mpz:
+    def _create_salt() -> int:
         # generate random salt
         salt = crypt.mksalt(crypt.METHOD_SHA512)[3:]
-        salt_b = salt.encode()
-        salt_hex = binascii.hexlify(salt_b)
-        salt_int = int(salt_hex, 16)
         assert len(salt) == 16
-        return gmpy2.mpz(salt_int)
+        salt_b = salt.encode()
+        return int.from_bytes(salt_b, "big")
 
     def _get_verifier(self) -> int:
         hash_value = self._calculate_x()
@@ -276,14 +268,13 @@ def verify_clients_proof(self, m) -> bool:
         hash_instance.update(Srp.to_byte_array(self.A))
         hash_instance.update(Srp.to_byte_array(self.B))
         hash_instance.update(K)
-        r = binascii.hexlify(hash_instance.digest())
-        return m == gmpy2.mpz(r, 16)
+        return m == int.from_bytes(hash_instance.digest(), "big")
 
-    def get_proof(self, m) -> gmpy2.mpz:
+    def get_proof(self, m) -> int:
         hash_instance = self.h()
         hash_instance.update(Srp.to_byte_array(self.A))
         hash_instance.update(Srp.to_byte_array(m))
         hash_instance.update(Srp.to_byte_array(self.get_session_key()))
-        return gmpy2.mpz(binascii.hexlify(hash_instance.digest()), 16)
+        return int.from_bytes(hash_instance.digest(), "big")
 
 

requirements.txt

@@ -1,5 +1,4 @@
 zeroconf
-gmpy2
 py25519
 hkdf
 ed25519

setup.py

@@ -40,7 +40,6 @@
     ],
     install_requires=[
         'zeroconf',
-        'gmpy2',
         'py25519',
         'hkdf',
         'ed25519',