Re: [gentoo-user] Heartbleed fix - question re: replacing self-signed certs with real ones

[Joe User <mailinglists@rootservice.org>]

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On 19.04.2014 17:38, Matti Nykyri wrote:
> On Apr 19, 2014, at 16:17, Joe User <mailinglists@rootservice.org>
> wrote:
> 
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>> 
>> On 19.04.2014 13:51, Mick wrote:
>>> On Thursday 17 Apr 2014 19:43:25 Matti Nykyri wrote:
>>>> On Thu, Apr 17, 2014 at 04:49:45PM +0100, Mick wrote:
>>> 
>>>>> Can you please share how you create ECDHE_ECDSA with
>>>>> openssl ecparam, or ping a URL if that is more convenient?
>>>> 
>>>> Select curve for ECDSA: openssl ecparam -out ec_param.pem
>>>> -name secp521r1
>>> [snip ...]
>>> 
>>>> I don't know much about the secp521r1 curve or about its 
>>>> security.
>>> [snip ...]
>>> 
>>> It seems that many sites that use ECDHE with various CA
>>> signature algorithms (ECC as well as conventional symmetric)
>>> use the secp521r1 curve - aka P-256. I just checked and
>>> gmail/google accounts use it too.
>>> 
>>> Markus showed secp384r1 (P-384) in his example.
>>> 
>>> The thing is guys that both of these are shown as 'unsafe' in
>>> the http://safecurves.cr.yp.to tables and are of course
>>> specified by NIST and NSA.
>>> 
>>> Thank you both for your replies.  I need to read a bit more
>>> into all this before I settle on a curve.
>>> 
>> 
>> 1.) secp521r1 is *not* P-256 2.) I used secp384r1 aka P-384 as
>> it's defined by RFC 6460 while secp521r1 is not, and all TLS1.2
>> implementations implement secp256r1 and secp384r1 as defined in
>> RFC 6460, while secp521r1 is implemented only by some. So better
>> to be RFC compliant and reach all possible users/customers as to
>> violate the RFC and loose possible users/customers. 
>> https://tools.ietf.org/html/rfc6460 3.) Even the people behind
>> http://safecurves.cr.yp.to have no proof that secp[256|384|521]r1
>> are unsecure, they just don't trust the NIST. So that list is
>> mostly useless and possibly untrue.
> 
> Which of the safecurves are supported by openssl?

openssl ecparam -list_curves

But openssl is not used by the major browsers and other clients,
so it is not a reference here.

>> 4.) ECC in certificates is not widely used and therfor also not 
>> extensivly audited, so it might be less secure than SHA256+RSA, 
>> or may suffer from implementation failures like heartbeat did. 
>> 5.) ECDSA has the same problems i mentioned in 4, so it may be a
>> bad idea to use it in production. Stick to ECDHE and as a
>> fallback to DHE. I use the following ciphers for my services: 
>> TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (0xc030) 
>> TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xc02f) 
>> TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (0xc028) 
>> TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (0xc027) 
>> TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (0xc014) 
>> TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (0xc013) 
>> TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (0x9f) 
>> TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (0x9e) 
>> TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (0x6b) 
>> TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (0x67) 
>> TLS_DHE_RSA_WITH_AES_256_CBC_SHA (0x39) 
>> TLS_DHE_RSA_WITH_AES_128_CBC_SHA (0x33)
> 
> What program do you use to provide IMAP-SSL/TLS? I have not gotten
> ECDHE to work with courier&openssl. Anyways I fail to see any logic
> with courier-setup... Postfix and apache on the other hand are easy
> to setup to use the correct ciphers.

I use Dovecot as IMAPd. If you're interested in how i setup my
servers then have a look at my corresponding howtos (in order):
http://www.rootservice.org/howtos/freebsd/remote_install.html
http://www.rootservice.org/howtos/freebsd/certificate_authority.html
http://www.rootservice.org/howtos/freebsd/hosting_system.html
My Gentoo-HowTos are out of date, so don't look at them ;)
But the configs should work also on Gentoo with little tweaks.


- -- 
Kind Regards,                             Mit freundlichen Grüssen,
Markus Kohlmeyer                                   Markus Kohlmeyer

PGP: 0xEBDF5E55 / 2A22 1F71 AA70 1AD1 231B 0178 759F 407C EBDF 5E55

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