Crypto plaintext padding

[David Clymer]

I'm using pycrypto's AES module, and am attempting to automate the
padding of the plaintext (the size of the text to be encrypted must be a
multiple of 16). However, my padding scheme sometimes fails to calculate
the necessary padding correctly, and I'm not sure why.

Using the text 'foo bar', it fails, but if I do 'foo bars' it works.
Randomized testing fails sometimes and not others.

Any pointers as to what I might be doing wrong (code attached)?

-davidc

-- 
gpg-key: http://www.zettazebra.com/files/key.gpg
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