Updated BLAKE2s and BLAKE2b error messages from unsupportedalgorithm … (#4519)

* Updated BLAKE2s and BLAKE2b error messages from unsupportedalgorithm exception to an explicit error.
The error is now "ValueError: Digest size must be 32" (or 64 for BLAKE2b)
This was done to give a more contextual error message and should be in place until OpenSSL supports variable lengths.

* Updated if statements in hashes.py so that they no longer wrap to separate line.
Updated test_hashes.py to unclude a test for non 32 or 64 digest_sizes that fall between 0-32/64.

* Removed the new tests in test_hashes.py as the old ones were satisfactory. This also solved misaligned tabs and spaces.

* Removed dead code in hashes.py that could no longer be reached after error message updates.

* pep8 fix

* remove superfluous parens

1 files changed, 6 insertions, 14 deletions

diff --git a/src/cryptography/hazmat/primitives/hashes.py b/src/cryptography/hazmat/primitives/hashes.py
index 89e66ab7..35b7d646 100644
--- a/src/cryptography/hazmat/primitives/hashes.py
+++ b/src/cryptography/hazmat/primitives/hashes.py
@@ -188,13 +188,9 @@ class BLAKE2b(object):
     block_size = 128
 
     def __init__(self, digest_size):
-        if (
-            digest_size > self._max_digest_size or
-            digest_size < self._min_digest_size
-        ):
-            raise ValueError("Digest size must be {0}-{1}".format(
-                self._min_digest_size, self._max_digest_size)
-            )
+
+        if digest_size != 64:
+            raise ValueError("Digest size must be 64")
 
         self._digest_size = digest_size
 
@@ -209,13 +205,9 @@ class BLAKE2s(object):
     _min_digest_size = 1
 
     def __init__(self, digest_size):
-        if (
-            digest_size > self._max_digest_size or
-            digest_size < self._min_digest_size
-        ):
-            raise ValueError("Digest size must be {0}-{1}".format(
-                self._min_digest_size, self._max_digest_size)
-            )
+
+        if digest_size != 32:
+            raise ValueError("Digest size must be 32")
 
         self._digest_size = digest_size