[erlang-questions] Compiling Erlang without RC4?

Oliver Korpilla <>
Tue Sep 13 23:03:03 CEST 2016

Hello, Alexander.

You misunderstand... I'm not concerned at all. The Linux distribution I have to work with removed the rc4.h header and without it I can not compile the Erlang runtime environment (and not deploy my application).

I did a cursory look but it is as you say - I found no guards and there were plenty of references towards definitions from that header, so I was a bit out on a limb to ask if anything knew a trick to compile the Erlang runtime without this header...


Gesendet: Dienstag, 13. September 2016 um 20:42 Uhr
Von: "Alexander Færøy" <>
An: erlang-questions <>
Betreff: Re: [erlang-questions] Compiling Erlang without RC4?
On 13 September 2016 at 17:16, Oliver Korpilla <> wrote:
> We currently have to work with a system where somebody thought removing rc4.h would solve the security issues involved with this weak algorithm...
> Is there any way to build Erlang without RC4 (but still with crypto functionality)?

It doesn't look like the RC4 functionality is hidden behind a guard in
the C source code, but I don't think you should be overly worried
about using an Erlang release that contains RC4 support.

If you take a look at the ciphers that the SSL application will use by
default, you will see that there's no RC4 ciphers included (at least
not in my OTP-18 installation locally):

lists:foreach(fun (Suite) -> io:format("~p~n", [Suite]) end,

You could consider filtering out the 3DES ciphers that are enabled by
default though[1] using the {ciphers, [...]} option for SSL


[1]: https://sweet32.info

Alexander Færøy
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