On Fri, Jun 30, 2006 at 07:29:04AM -0400, Victor Duchovni wrote:
>>> Currently I specify the group (HIGH/MEDIUM/LOW) and remove some ciphers
>>> from a group (IDEA and ADH). I also remove AES at the beginning (Shif
>>> +="-AES:") and add it later because if I don't remove AES there is no
>>> way to separate AES128 and AES256.
>>> (Due to an OpenSSL bug, HIGH selects both AES128 and AES256)
It's not a bug that AES182 is classified as "HIGH", although it is a
missing feature that there is no class that encompasses only the
256-bit ciphers. That's why there now is "@STRENGTH", which does
not add any ciphers and just sorts the one enabled so far.
>> Is this a real problem? What's wrong with:
>>
>>
>> !EXPORT:!LOW:!MEDIUM:DEFAULT:-DHE-RSA-AES128-SHA:-DHE-DSS-AES128-SHA:-AES128-SHA
> Sorry, I guess this ("DEFAULT:" should have been first) does not work,
> because removing the 128 bit ciphers also removes the 256 bit ciphers.
>
> With:
>
> $ openssl ciphers -v \
> 'DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA:AES128-SHA:@STRENGTH'
> DHE-RSA-AES256-SHA SSLv3 Kx=DH Au=RSA Enc=AES(256) Mac=SHA1
> DHE-DSS-AES256-SHA SSLv3 Kx=DH Au=DSS Enc=AES(256) Mac=SHA1
> AES256-SHA SSLv3 Kx=RSA Au=RSA Enc=AES(256) Mac=SHA1
> DHE-RSA-AES128-SHA SSLv3 Kx=DH Au=RSA Enc=AES(128) Mac=SHA1
> DHE-DSS-AES128-SHA SSLv3 Kx=DH Au=DSS Enc=AES(128) Mac=SHA1
> AES128-SHA SSLv3 Kx=RSA Au=RSA Enc=AES(128) Mac=SHA1
>
> and
>
> $ openssl ciphers -v \
> 'DHE-RSA-AES256-SHA:DHE-DSS-AES256-SHA:AES256-SHA:@STRENGTH'
> DHE-RSA-AES256-SHA SSLv3 Kx=DH Au=RSA Enc=AES(256) Mac=SHA1
> DHE-DSS-AES256-SHA SSLv3 Kx=DH Au=DSS Enc=AES(256) Mac=SHA1
> AES256-SHA SSLv3 Kx=RSA Au=RSA Enc=AES(256) Mac=SHA1
> DHE-RSA-AES128-SHA SSLv3 Kx=DH Au=RSA Enc=AES(128) Mac=SHA1
> DHE-DSS-AES128-SHA SSLv3 Kx=DH Au=DSS Enc=AES(128) Mac=SHA1
> AES128-SHA SSLv3 Kx=RSA Au=RSA Enc=AES(128) Mac=SHA1
>
> producing the same results you are out of luck, if you want 256 bit AES,
> you always also get 128 bit AES.
It appears that you are using OpenSSL 0.9.8 or 0.9.8a here. This is a
bug that should be fixed in OpenSSL 0.9.8b, so that the
DHE-RSA-AES256-SHA:DHE-DSS-AES256-SHA:AES256-SHA ciphersuite
specification (with or without :STRENGTH appended) will only yield the
three ciphersuites intended.
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