Re: [Classpathx-crypto] on testing (long)

[Casey Marshall]

On Sun, 23 Jun 2002, Raif S. Naffah wrote:

>
> [...]
>
> i'd go with (c).
>
> * if we go with (b) or (c), how many hard-coded test vectors should we
> use?  --all of them is out of the question because of size and speed.
> theoretically one value should be enough, but 3 is more "re-assuring."
>
> * should there be any special criteria for selecting the agreed number
> of test-vectors? or throwing a dice would suffice?
>

I would go with (c), too. As far as the number of test cases to hard-code,
I would recommend *at least* two of each of the monte-carlo tests, so there
is at least one change of key. This is because if a test only does the
first monte-carlo test, a problem with endianess *could* sneak by, since
the all-zero key looks the same regardless of endianness (this did happen
early on when I was working on the Serpent implementation, when I only
checked the all-zero key).

For the known-answer tests I would recommend using texts/keys where a bit
is set somewhere in each byte/nybble/word, to try to cover a range, not
just the first few.

Other than that I would simply use a Comfortable Round Number.

> * once we have coded those TestOfxxx for our ciphers.  should we still
> keep the selfTest() method in the API and implementations?
>
> in its actual form the setlfTest() for the ciphers only test for
> symmetry, which may be true even for incorrectly implemented ciphers.
> in other words it's almost useless!
>
> we should change it to either (a) something similar to the selfTest() of
> hash algorithms, (b) something similar to the TestOfxxx discussed above
> with some hard-coded test vectors, or (c) get rid of it altogether!
>

I would go for encrypting a known text, comparing the ciphertext with a
known answer, then decrypting it to see if it results in the plaintext.

-- 
Casey Marshall < address@hidden > http://metastatic.org/