[erlang-questions] SSL and hardcoded DH prime

[Alexander Petrovsky]

>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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