Require cryptography >= 1.4, replace deprecated function

The signer/verifier interfaces are deprecated in cryptography==2.0. The
alternative sign/verify interfaces were added in cryptography==1.4.

3 files changed, 19 insertions, 43 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2049b29..78b2da0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,7 +7,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 [Unreleased][unreleased]
 -------------------------------------------------------------------------
 ### Changed
+- Increase required version of the cryptography package to >=1.4.0.
 ### Fixed
+- Remove uses of deprecated functions from the cryptography package.
 ### Added
 
 [v1.5.2][1.5.2]
diff --git a/jwt/algorithms.py b/jwt/algorithms.py
index 47043c3..1343688 100644
--- a/jwt/algorithms.py
+++ b/jwt/algorithms.py
@@ -231,7 +231,7 @@ if has_crypto:
                     'qi': force_unicode(to_base64url_uint(numbers.iqmp))
                 }
 
-            elif getattr(key_obj, 'verifier', None):
+            elif getattr(key_obj, 'verify', None):
                 # Public key
                 numbers = key_obj.public_numbers()
 
@@ -310,25 +310,11 @@ if has_crypto:
                 raise InvalidKeyError('Not a public or private key')
 
         def sign(self, msg, key):
-            signer = key.signer(
-                padding.PKCS1v15(),
-                self.hash_alg()
-            )
-
-            signer.update(msg)
-            return signer.finalize()
+            return key.sign(msg, padding.PKCS1v15(), self.hash_alg())
 
         def verify(self, msg, key, sig):
-            verifier = key.verifier(
-                sig,
-                padding.PKCS1v15(),
-                self.hash_alg()
-            )
-
-            verifier.update(msg)
-
             try:
-                verifier.verify()
+                key.verify(sig, msg, padding.PKCS1v15(), self.hash_alg())
                 return True
             except InvalidSignature:
                 return False
@@ -370,10 +356,7 @@ if has_crypto:
             return key
 
         def sign(self, msg, key):
-            signer = key.signer(ec.ECDSA(self.hash_alg()))
-
-            signer.update(msg)
-            der_sig = signer.finalize()
+            der_sig = key.sign(msg, ec.ECDSA(self.hash_alg()))
 
             return der_to_raw_signature(der_sig, key.curve)
 
@@ -383,12 +366,8 @@ if has_crypto:
             except ValueError:
                 return False
 
-            verifier = key.verifier(der_sig, ec.ECDSA(self.hash_alg()))
-
-            verifier.update(msg)
-
             try:
-                verifier.verify()
+                key.verify(der_sig, msg, ec.ECDSA(self.hash_alg()))
                 return True
             except InvalidSignature:
                 return False
@@ -399,7 +378,8 @@ if has_crypto:
         """
 
         def sign(self, msg, key):
-            signer = key.signer(
+            return key.sign(
+                msg,
                 padding.PSS(
                     mgf=padding.MGF1(self.hash_alg()),
                     salt_length=self.hash_alg.digest_size
@@ -407,23 +387,17 @@ if has_crypto:
                 self.hash_alg()
             )
 
-            signer.update(msg)
-            return signer.finalize()
-
         def verify(self, msg, key, sig):
-            verifier = key.verifier(
-                sig,
-                padding.PSS(
-                    mgf=padding.MGF1(self.hash_alg()),
-                    salt_length=self.hash_alg.digest_size
-                ),
-                self.hash_alg()
-            )
-
-            verifier.update(msg)
-
             try:
-                verifier.verify()
+                key.verify(
+                    sig,
+                    msg,
+                    padding.PSS(
+                        mgf=padding.MGF1(self.hash_alg()),
+                        salt_length=self.hash_alg.digest_size
+                    ),
+                    self.hash_alg()
+                )
                 return True
             except InvalidSignature:
                 return False
diff --git a/setup.py b/setup.py
index 7124ded..e8c54cf 100755
--- a/setup.py
+++ b/setup.py
@@ -70,7 +70,7 @@ setup(
     tests_require=tests_require,
     extras_require=dict(
         test=tests_require,
-        crypto=['cryptography >= 1.0'],
+        crypto=['cryptography >= 1.4'],
         flake8=[
             'flake8',
             'flake8-import-order',