text: #! /usr/bin/python
  
  import unittest
  
  from curve25519 import Private, Public
  from hashlib import sha1, sha256
  from binascii import hexlify
  
  class Basic(unittest.TestCase):
      def test_basic(self):
          secret1 = b"abcdefghijklmnopqrstuvwxyz123456"
          self.assertEqual(len(secret1), 32)
  
          secret2 = b"654321zyxwvutsrqponmlkjihgfedcba"
          self.assertEqual(len(secret2), 32)
          priv1 = Private(secret=secret1)
          pub1 = priv1.get_public()
          priv2 = Private(secret=secret2)
          pub2 = priv2.get_public()
          shared12 = priv1.get_shared_key(pub2)
          e = b"b0818125eab42a8ac1af5e8b9b9c15ed2605c2bbe9675de89e5e6e7f442b9598"
          self.assertEqual(hexlify(shared12), e)
          shared21 = priv2.get_shared_key(pub1)
          self.assertEqual(shared12, shared21)
  
          pub2a = Public(pub2.serialize())
          shared12a = priv1.get_shared_key(pub2a)
          self.assertEqual(hexlify(shared12a), e)
  
      def test_errors(self):
          priv1 = Private()
          self.assertRaises(ValueError, priv1.get_shared_key, priv1)
  
      def test_seed(self):
          # use 32-byte secret
          self.assertRaises(TypeError, Private, secret=123)
          self.assertRaises(TypeError, Private, secret=b"too short")
          secret1 = b"abcdefghijklmnopqrstuvwxyz123456"
          assert len(secret1) == 32
          priv1 = Private(secret=secret1)
          priv1a = Private(secret=secret1)
          priv1b = Private(priv1.serialize())
          self.assertEqual(priv1.serialize(), priv1a.serialize())
          self.assertEqual(priv1.serialize(), priv1b.serialize())
          e = b"6062636465666768696a6b6c6d6e6f707172737475767778797a313233343576"
          self.assertEqual(hexlify(priv1.serialize()), e)
  
          # the private key is a clamped form of the secret, so they won't
          # quite be the same
          p = Private(secret=b"\x00"*32)
          self.assertEqual(hexlify(p.serialize()), b"00"*31+b"40")
          p = Private(secret=b"\xff"*32)
          self.assertEqual(hexlify(p.serialize()), b"f8"+b"ff"*30+b"7f")
  
          # use arbitrary-length seed
          self.assertRaises(TypeError, Private, seed=123)
          priv1 = Private(seed=b"abc")
          priv1a = Private(seed=b"abc")
          priv1b = Private(priv1.serialize())
          self.assertEqual(priv1.serialize(), priv1a.serialize())
          self.assertEqual(priv1.serialize(), priv1b.serialize())
          self.assertRaises(AssertionError, Private, seed=b"abc", secret=b"no")
  
          priv1 = Private(seed=b"abc")
          priv1a = Private(priv1.serialize())
          self.assertEqual(priv1.serialize(), priv1a.serialize())
          self.assertRaises(AssertionError, Private, seed=b"abc", secret=b"no")
  
          # use built-in os.urandom
          priv2 = Private()
          priv2a = Private(priv2.private)
          self.assertEqual(priv2.serialize(), priv2a.serialize())
  
          # attempt to use both secret= and seed=, not allowed
          self.assertRaises(AssertionError, Private, seed=b"abc", secret=b"no")
  
      def test_hashfunc(self):
          priv1 = Private(seed=b"abc")
          priv2 = Private(seed=b"def")
          shared_sha256 = priv1.get_shared_key(priv2.get_public())
          e = b"da959ffe77ebeb4757fe5ba310e28ede425ae0d0ff5ec9c884e2d08f311cf5e5"
          self.assertEqual(hexlify(shared_sha256), e)
  
          # confirm the hash function remains what we think it is
          def myhash(shared_key):
              return sha256(b"curve25519-shared:"+shared_key).digest()
          shared_myhash = priv1.get_shared_key(priv2.get_public(), myhash)
          self.assertEqual(hexlify(shared_myhash), e)
  
          def hexhash(shared_key):
              return sha1(shared_key).hexdigest().encode()
          shared_hexhash = priv1.get_shared_key(priv2.get_public(), hexhash)
          self.assertEqual(shared_hexhash,
                               b"80eec98222c8edc4324fb9477a3c775ce7c6c93a")
  
  
  if __name__ == "__main__":
      unittest.main()
  
  