Fixes #4734 -- Deal with deprecated things (#4736)

* Fixes #4734 -- Deal with deprecated things

- Make year based aliases of PersistentlyDeprecated so we can easily assess age
- Removed encode/decode rfc6979 signature
- Removed Certificate.serial

* Unused import

6 files changed, 7 insertions, 40 deletions

diff --git a/src/cryptography/hazmat/backends/openssl/utils.py b/src/cryptography/hazmat/backends/openssl/utils.py
index 363f3d2c..ee472c0e 100644
--- a/src/cryptography/hazmat/backends/openssl/utils.py
+++ b/src/cryptography/hazmat/backends/openssl/utils.py
@@ -64,6 +64,6 @@ def _warn_sign_verify_deprecated():
     warnings.warn(
         "signer and verifier have been deprecated. Please use sign "
         "and verify instead.",
-        utils.PersistentlyDeprecated,
+        utils.PersistentlyDeprecated2017,
         stacklevel=3
     )
diff --git a/src/cryptography/hazmat/backends/openssl/x509.py b/src/cryptography/hazmat/backends/openssl/x509.py
index ac1838c6..b3eb797d 100644
--- a/src/cryptography/hazmat/backends/openssl/x509.py
+++ b/src/cryptography/hazmat/backends/openssl/x509.py
@@ -6,7 +6,6 @@ from __future__ import absolute_import, division, print_function
 
 import datetime
 import operator
-import warnings
 
 from cryptography import utils, x509
 from cryptography.exceptions import UnsupportedAlgorithm
@@ -63,15 +62,6 @@ class _Certificate(object):
             )
 
     @property
-    def serial(self):
-        warnings.warn(
-            "Certificate serial is deprecated, use serial_number instead.",
-            utils.PersistentlyDeprecated,
-            stacklevel=2
-        )
-        return self.serial_number
-
-    @property
     def serial_number(self):
         asn1_int = self._backend._lib.X509_get_serialNumber(self._x509)
         self._backend.openssl_assert(asn1_int != self._backend._ffi.NULL)
diff --git a/src/cryptography/hazmat/primitives/asymmetric/utils.py b/src/cryptography/hazmat/primitives/asymmetric/utils.py
index ef1e7eb9..274c1f41 100644
--- a/src/cryptography/hazmat/primitives/asymmetric/utils.py
+++ b/src/cryptography/hazmat/primitives/asymmetric/utils.py
@@ -4,8 +4,6 @@
 
 from __future__ import absolute_import, division, print_function
 
-import warnings
-
 from asn1crypto.algos import DSASignature
 
 import six
@@ -14,31 +12,11 @@ from cryptography import utils
 from cryptography.hazmat.primitives import hashes
 
 
-def decode_rfc6979_signature(signature):
-    warnings.warn(
-        "decode_rfc6979_signature is deprecated and will "
-        "be removed in a future version, use decode_dss_signature instead.",
-        utils.PersistentlyDeprecated,
-        stacklevel=2
-    )
-    return decode_dss_signature(signature)
-
-
 def decode_dss_signature(signature):
     data = DSASignature.load(signature, strict=True).native
     return data['r'], data['s']
 
 
-def encode_rfc6979_signature(r, s):
-    warnings.warn(
-        "encode_rfc6979_signature is deprecated and will "
-        "be removed in a future version, use encode_dss_signature instead.",
-        utils.PersistentlyDeprecated,
-        stacklevel=2
-    )
-    return encode_dss_signature(r, s)
-
-
 def encode_dss_signature(r, s):
     if (
         not isinstance(r, six.integer_types) or
diff --git a/src/cryptography/hazmat/primitives/constant_time.py b/src/cryptography/hazmat/primitives/constant_time.py
index 0e987ea7..99a114e2 100644
--- a/src/cryptography/hazmat/primitives/constant_time.py
+++ b/src/cryptography/hazmat/primitives/constant_time.py
@@ -23,7 +23,7 @@ else:
         "Support for your Python version is deprecated. The next version of "
         "cryptography will remove support. Please upgrade to a 2.7.x "
         "release that supports hmac.compare_digest as soon as possible.",
-        utils.DeprecatedIn23,
+        utils.PersistentlyDeprecated2018,
     )
 
     def bytes_eq(a, b):
diff --git a/src/cryptography/utils.py b/src/cryptography/utils.py
index cbbae3a7..567600fb 100644
--- a/src/cryptography/utils.py
+++ b/src/cryptography/utils.py
@@ -20,9 +20,8 @@ class CryptographyDeprecationWarning(UserWarning):
 # Several APIs were deprecated with no specific end-of-life date because of the
 # ubiquity of their use. They should not be removed until we agree on when that
 # cycle ends.
-PersistentlyDeprecated = CryptographyDeprecationWarning
-DeprecatedIn21 = CryptographyDeprecationWarning
-DeprecatedIn23 = CryptographyDeprecationWarning
+PersistentlyDeprecated2017 = CryptographyDeprecationWarning
+PersistentlyDeprecated2018 = CryptographyDeprecationWarning
 DeprecatedIn25 = CryptographyDeprecationWarning
 
 
diff --git a/src/cryptography/x509/general_name.py b/src/cryptography/x509/general_name.py
index 1b0f8c8f..fef29c8c 100644
--- a/src/cryptography/x509/general_name.py
+++ b/src/cryptography/x509/general_name.py
@@ -72,7 +72,7 @@ class RFC822Name(object):
                     "This means unicode characters should be encoded via "
                     "idna. Support for passing unicode strings (aka U-label) "
                     "will be removed in a future version.",
-                    utils.DeprecatedIn21,
+                    utils.PersistentlyDeprecated2017,
                     stacklevel=2,
                 )
         else:
@@ -139,7 +139,7 @@ class DNSName(object):
                     "This means unicode characters should be encoded via "
                     "idna. Support for passing unicode strings (aka U-label) "
                     "will be removed in a future version.",
-                    utils.DeprecatedIn21,
+                    utils.PersistentlyDeprecated2017,
                     stacklevel=2,
                 )
         else:
@@ -184,7 +184,7 @@ class UniformResourceIdentifier(object):
                     "This means unicode characters should be encoded via "
                     "idna. Support for passing unicode strings (aka U-label) "
                     " will be removed in a future version.",
-                    utils.DeprecatedIn21,
+                    utils.PersistentlyDeprecated2017,
                     stacklevel=2,
                 )
         else: