* Prevent pkcs5_pbe2 encryption when PKCS7 padding has been
disabled since this not part of the specs.
* Allow decryption when PKCS7 padding is disabled for legacy
reasons, However, invalid padding is not checked.
* Add tests to check these scenarios. Test data has been
reused but with changing padding data in last block to
check for valid/invalid padding.
* Document new behaviour, known limitations and possible
security concerns.
Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
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