Commits on Oct 9, 2015

1. VaultLib interface cleanups: remove .cipher_name, move .version …

   As noted in the comments in PR #12112, the cipher_name stored in the
   VaultLib conflates the desired cipher for encryption with the cipher
   read from an encrypted file header. This change makes the encryption
   cipher a parameter to encrypt() and changes _split_header() to return
   the extracted values so that decrypt() can use the appropriate cipher
   name (which a new helper transforms into a VaultXXX class).
   
   As a consequence, _split_header is renamed to _parse_vault_file, which
   also becomes more strict about parsing vault headers. (This also means
   that decrypt() doesn't have to check is_encrypted() separately, since
   the validation is being done anyway.)
   
   We also move b_version from VaultLib to the individual cipher classes so
   that they can manage their own versioning; we also pass the version from
   the file header to the cipher's decrypt() method.
   
   This doesn't change any functionality, but it paves the way for easier
   format changes without having to introduce ever more cipher classes.

   

   amenonsen committed Oct 9, 2015
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2. Introduce an improved AES256 cipher version …

   Now we don't add spurious padding for AES-CTR (which is used as a stream
   cipher, and doesn't need padding) and we use base64 to encode the output
   message instead of blowing up its size by hexlify()ing everything twice.
   We also don't unnecessarily use PBKDF2 to generate the initial value for
   the encryption counter.
   
   We always use the new format for output, but maintain read-compatibility
   with a few lines of 1.1-specific decoding in decrypt(). (Note that we do
   not force v1.1 files to be rewritten by ansible-vault edit unless their
   contents have actually changed, in which case the new cipher version is
   used automatically).
   
   Closes #10634 from graingert (which removed the padding, but added yet
   another cipher class for backwards compatibility)
   
   Fixes #12121 from mgedmin (which reported the double-hexlify() problem)

   

   amenonsen committed Oct 9, 2015
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3. Add a vault header version in addition to the cipher version …

   The header now looks like this: $ANSIBLE_VAULT;1.2;AES256;1.2
   
   The vault header version is currently not used to convey any extra
   information. It's included in the hope that it will help to escape
   unforeseen problems.
   
   The earlier _format_output method is renamed to _add_vault_header, and
   is no longer responsible for wrapping the output at 80 columns (cipher
   classes are now responsible for doing their own formatting; GPG would
   need this anyway).
   
   The _parse_vault_file method is renamed to _parse_vault_header, and is
   no longer responsible for unwrapping the ciphertext (cipher classes are
   responsible for undoing whatever formatting they originally did).
   
   A new decrypt_with_metadata method is introduced primarily so that
   VaultEditor can find the cipher_name to see if it wants to upgrade
   to a new cipher or not.
   
   These changes were made at the request of @abadger.

   

   amenonsen committed Oct 9, 2015
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4. Four changes related to parsing the Vault File header …

   * Have internal VaultLib functions dealing with the header return byte strings
   * Switch finding the Ciphers to use a mapping for safety
   * If we recognize an invalid vault file while parsing the header, throw
     an exception there instead of making a higher level decide that.
   * Make version comparison robust against double digit versions

   

   abadger authored and amenonsen committed Oct 9, 2015
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5. Consolidate decrypt and decrypt_with_metadata into a single method

   

   abadger authored and amenonsen committed Oct 9, 2015
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