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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.
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)
- --
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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