Require cryptography >= 1.0, replace deprecated function

The functions `decode_rfc6979_signature` and `encode_rfc6979_signature`
were deprecated in cryptography 1.0:
    https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst#10---2015-08-12
and raise a DeprecationWarning now. The replacements are exactly the same.

1 files changed, 1 insertions, 1 deletions

diff --git a/setup.py b/setup.py
index 274f249..a2bd736 100755
--- a/setup.py
+++ b/setup.py
@@ -69,7 +69,7 @@ setup(
     tests_require=tests_require,
     extras_require=dict(
         test=tests_require,
-        crypto=['cryptography'],
+        crypto=['cryptography >= 1.0'],
         flake8=[
             'flake8',
             'flake8-import-order',