added back changelog

Author: nitneuqr

CHANGELOG.rst

@@ -21,6 +21,12 @@ Changelog
 * Removed the deprecated ``CAST5``, ``SEED``, ``IDEA``, and ``Blowfish``
   classes from the cipher module. These are still available in
   :doc:`/hazmat/decrepit/index`.
+* Added support for PKCS7 decryption & encryption using AES-256 as content algorithm, 
+  in addition to AES-128. 
+* Added basic support for PKCS7 verification (including S/MIME 3.2) via
+  :func:`~cryptography.hazmat.primitives.serialization.pkcs7.pkcs7_verify_der`,
+  :func:`~cryptography.hazmat.primitives.serialization.pkcs7.pkcs7_verify_pem`, and
+  :func:`~cryptography.hazmat.primitives.serialization.pkcs7.pkcs7_verify_smime`.
 
 .. _v45-0-7: