Merge "Adding support for 512-Bit-Secret-Creation when using xts-mode"

barbican/plugin/crypto/simple_crypto.py

@@ -192,10 +192,12 @@ class SimpleCryptoPlugin(c.CryptoPluginBase):
 
         if type_enum == c.PluginSupportTypes.SYMMETRIC_KEY_GENERATION:
             return self._is_algorithm_supported(algorithm,
-                                                bit_length)
+                                                bit_length,
+                                                mode)
         elif type_enum == c.PluginSupportTypes.ASYMMETRIC_KEY_GENERATION:
             return self._is_algorithm_supported(algorithm,
-                                                bit_length)
+                                                bit_length,
+                                                mode)
         else:
             return False
 
@@ -217,14 +219,23 @@ class SimpleCryptoPlugin(c.CryptoPluginBase):
 
         return algorithm
 
-    def _is_algorithm_supported(self, algorithm=None, bit_length=None):
+    def _is_algorithm_supported(self, algorithm=None,
+                                bit_length=None, mode=None):
         """check if algorithm and bit_length combination is supported."""
         if algorithm is None or bit_length is None:
             return False
 
-        if (algorithm.lower() in
-                c.PluginSupportTypes.SYMMETRIC_ALGORITHMS and bit_length in
-                c.PluginSupportTypes.SYMMETRIC_KEY_LENGTHS):
+        length_factor = 1
+
+        # xts-mode cuts the effective key for the algorithm in half,
+        # so the bit_length must be the double of the supported length.
+        # in the future there should be a validation of supported modes too.
+        if mode is not None and mode.lower() == "xts":
+            length_factor = 2
+
+        if (algorithm.lower() in c.PluginSupportTypes.SYMMETRIC_ALGORITHMS
+            and bit_length/length_factor
+                in c.PluginSupportTypes.SYMMETRIC_KEY_LENGTHS):
             return True
         elif (algorithm.lower() in c.PluginSupportTypes.ASYMMETRIC_ALGORITHMS
               and bit_length in c.PluginSupportTypes.ASYMMETRIC_KEY_LENGTHS):

releasenotes/notes/allow-aes-xts-512-bitlength-in-simple-crypto-95936a2d830035cc.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    By default barbican checks only the algorithm and the bit_length when
+    creating a new secret. The xts-mode cuts the key in half for aes, so for
+    using aes-256 with xts, you have to use a 512 bit key, but barbican allows
+    only a maximum of 256 bit. A check for the mode within the
+    _is_algorithm_supported method of the class SimpleCryptoPlugin was added
+    to allow 512 bit keys for aes-xts in this plugin.