[erlang-questions] SSL and hardcoded DH prime

[Frank Muller]

It’s not about that. Generating a 2048 DH can take a long time. And you
said it’s fast and you want to make it real time.

>From official ssl doc
> http://erlang.org/doc/man/ssl.html
>
> *{dh, public_key:der_encoded()}*
>
> The DER-encoded Diffie-Hellman parameters. If specified, it overrides
> option dhfile.
>
> пт, 24 авг. 2018 г. в 6:11, Frank Muller <frank.muller.erl@REDACTED>:
>
>> How? Show us please!!!
>>
>> No, I can use dh option in Erlang and generate in des format DH prime and
>>> DH generator. It’s very fast.
>>>
>>> чт, 23 авг. 2018 г. в 22:07, Paul Peregud <paulperegud@REDACTED>:
>>>
>>>> Its a long-ish process. But you can run it during installation or first
>>>> run.
>>>>
>>>> $ time openssl dhparam -out dhparam.pem 2048
>>>> ...
>>>> real    0m3,623s
>>>> user    0m3,612s
>>>> sys    0m0,000s
>>>>
>>>>
>>>>
>>>> On Thu, Aug 23, 2018 at 5:27 PM Alexander Petrovsky <askjuise@REDACTED>
>>>> wrote:
>>>>
>>>>> Yeah, Ingela, thanks! About default value and dh, dhfile options I
>>>>> know. The main question - is the any reasons don’t generate DH prime in
>>>>> real-time?
>>>>>
>>>>> чт, 23 авг. 2018 г. в 20:12, Ingela Andin <ingela.andin@REDACTED>:
>>>>>
>>>>>> Hi!
>>>>>>
>>>>>> It is only the default value that is hard coded (a recommend value),
>>>>>> you may configure your own parameters with dh or dhfile option.
>>>>>>
>>>>>> Regards Ingela
>>>>>>
>>>>>> Den tors 23 aug. 2018 kl 16:57 skrev Alexander Petrovsky <
>>>>>> askjuise@REDACTED>:
>>>>>>
>>>>>>> Hello!
>>>>>>>
>>>>>>> We have stumble upon default DH prime (2048 bits) in Erlang when we
>>>>>>> try to establish TLS session with cisco spa303 (VoIP hardphone)
>>>>>>> via TLS_DHE_RSA_WITH_AES_256_CBC_SHA (0x0039) cipher suite. Unfortunately,
>>>>>>> this hardphone can work only with 1024 bit DH prime.
>>>>>>>
>>>>>>> I wonder, why Ingela hardcoded this DH prime -
>>>>>>> https://github.com/erlang/otp/commit/3458af579af6600870c5ada69b81085f47e9f52b
>>>>>>>
>>>>>>> In my synthetical tests, new DH prime generation is fast enough
>>>>>>> (crypto:strong_rand_bytes(256)), about 17 us in 99 percentile in 1000000
>>>>>>> iterations.
>>>>>>>
>>>>>>> Why Ingela has hardcoded this DH prime and is any reason why I
>>>>>>> shouldn't generate DH prime in real-time?
>>>>>>>
>>>>>>> --
>>>>>>> Петровский Александр / Alexander Petrovsky,
>>>>>>>
>>>>>>> Skype: askjuise
>>>>>>> Phone: +7 931 9877991
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> erlang-questions mailing list
>>>>>>> erlang-questions@REDACTED
>>>>>>> http://erlang.org/mailman/listinfo/erlang-questions
>>>>>>>
>>>>>> --
>>>>> Петровский Александр / Alexander Petrovsky,
>>>>>
>>>>> Skype: askjuise
>>>>> Phone: +7 931 9877991
>>>>>
>>>>> _______________________________________________
>>>>> erlang-questions mailing list
>>>>> erlang-questions@REDACTED
>>>>> http://erlang.org/mailman/listinfo/erlang-questions
>>>>>
>>>>
>>>>
>>>> --
>>>> Best regards,
>>>> Paul Peregud
>>>> +48602112091
>>>>
>>> --
>>> Петровский Александр / Alexander Petrovsky,
>>>
>>> Skype: askjuise
>>> Phone: +7 931 9877991
>>>
>>> _______________________________________________
>>> erlang-questions mailing list
>>> erlang-questions@REDACTED
>>> http://erlang.org/mailman/listinfo/erlang-questions
>>>
>> --
> Петровский Александр / Alexander Petrovsky,
>
> Skype: askjuise
> Phone: +7 931 9877991
>
>
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