Now that VaultLib always decides to use AES256 to encrypt, we don't need
this broken code any more. We need to be able to decrypt this format for
a while longer, but encryption support can be safely dropped.
Now we don't have to recreate VaultEditor objects for each file, and so
on. It also paves the way towards specifying separate input and output
files later.
It's unused and unnecessary; VaultLib can decide for itself what cipher
to use when encrypting. There's no need (and no provision) for the user
to override the cipher via options, so there's no need for code to see
if that has been done either.
When stretching the key for vault files, use PBKDF2HMAC() from the
cryptography package instead of pycrypto. This will speed up the opening
of vault files by ~10x.
The problem is here in lib/ansible/utils/vault.py:
hash_function = SHA256
# make two keys and one iv
pbkdf2_prf = lambda p, s: HMAC.new(p, s, hash_function).digest()
derivedkey = PBKDF2(password, salt, dkLen=(2 * keylength) + ivlength,
count=10000, prf=pbkdf2_prf)
`PBKDF2()` calls a Python callback function (`pbkdf2_pr()`) 10000 times.
If one has several vault files, this will cause excessive start times
with `ansible` or `ansible-playbook` (we experience ~15 second startup
times).
Testing the original implementation in 1.9.2 with a vault file:
In [2]: %timeit v.decrypt(encrypted_data)
1 loops, best of 3: 265 ms per loop
Having a recent OpenSSL version and using the vault.py changes in this commit:
In [2]: %timeit v.decrypt(encrypted_data)
10 loops, best of 3: 23.2 ms per loop
