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http://bugs.exim.org/show_bug.cgi?id=1397 --- Comment #3 from Phil Pennock <[email protected]> 2013-10-15 05:21:20 --- I don't know enough about cryptanalysis of EC to advocate for any particular curve. I don't know enough about this undocumented API of OpenSSL to know how to add _both_ curves, and dynamically select the right one depending upon the bit-strength of AES in use. Frankly, the more I look at this, the more inclined I am to say that 4.82 should go out without explicit support for enabling ECDHE, so that we can better understand the issues. A quick and simple fix, as uninvasive as possible, is one thing, but this now looks like that's just inadequate. Jeremy, Todd, please do *not* merge the `enable_ecdhe` branch for 4.82. With our luck, it would turn out to break clients that barf when ECDHE suddenly becomes available anyway. Looking more closely, it seems that OpenSSL 1.0.2 will add the `SSL_CTX_set1_curves_list()` call, to specify a list of potential curves. It also looks as though 1.0.2 will introduce a new `SSL_CONF_cmd()` framework for applications to tune arbitrary options and that Exim should add support for that, which will automatically add support for curve specification via `-curves`. Given that OpenSSL has not stabilised their API for cleanly and correctly configuring ECDHE support, I do not think Exim should start using the interfaces in the currently released versions of OpenSSL. In the meantime, if ECDHE matters then I suggest using GnuTLS with Exim and providing the control options via the Priority String which can be given in Exim's `tls_require_ciphers` option. -- Configure bugmail: http://bugs.exim.org/userprefs.cgi?tab=email -- ## List details at https://lists.exim.org/mailman/listinfo/exim-dev Exim details at http://www.exim.org/ ##
