Merge pull request #211 from alex/stream-ciphers

Document how this returns bytes

1 files changed, 8 insertions, 1 deletions

diff --git a/docs/hazmat/primitives/symmetric-encryption.rst b/docs/hazmat/primitives/symmetric-encryption.rst
index 5852dc21..b8b1c839 100644
--- a/docs/hazmat/primitives/symmetric-encryption.rst
+++ b/docs/hazmat/primitives/symmetric-encryption.rst
@@ -63,6 +63,12 @@ where the encrypter and decrypter both use the same key.
         :param bytes data: The data you wish to pass into the context.
         :return bytes: Returns the data that was encrypted or decrypted.
 
+        When the ``BlockCipher`` was constructed in a mode turns it into a
+        stream cipher (e.g.
+        :class:`cryptography.hazmat.primitives.block.modes.CTR`), this will
+        return bytes immediately, however in other modes it will return chunks,
+        whose size is determined by the cipher's block size.
+
     .. method:: finalize()
 
         :return bytes: Returns the remainder of the data.
@@ -162,7 +168,8 @@ Modes
         block size of less than 128-bits.
 
     CTR (Counter) is a mode of operation for block ciphers. It is considered
-    cryptographically strong.
+    cryptographically strong. It transforms a block cipher into a stream
+    cipher.
 
     :param bytes nonce: Should be random bytes. It is critical to never reuse a
                         ``nonce`` with a given key.  Any reuse of a nonce