v2.5.3: missing bits

[hdatma]

Ref. https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.5.3-relnotes.txt

• Curve25519 Key Exchange support.

>openssl ecparam -list_curves | grep 25519
[empty]

• libtls now handles 4 cipher suite groups:
  "secure" (TLSv1.2+AEAD+PFS)
  "compat" (HIGH:!aNULL)
  "legacy" (HIGH:MEDIUM:!aNULL)
  "insecure" (ALL:!aNULL:!eNULL)
  This allows for flexibility and finer grained control, rather than having
  two extremes (an issue raised by Marko Kreen some time ago).

>openssl ciphers TLSv1.2+AEAD+PFS         
140736644547592:error:14FFF0B9:SSL routines:(UNKNOWN)SSL_internal:no cipher match:ssl_lib.c:1300:

[leonklingele]

openssl ecparam -list_curves | grep 25519
[empty]

X25519 does not work the same as the other eliptical curves, so it is expected that it
will not show up under ecparam's list. Try the same openssl ecparam -list_curves
operation with OpenSSL 1.1.0, which also has X25519, and you will see the same result.

#114 (comment)

[hdatma]

The fact that the specific EC does not work as other ECs does not justify the absence of the same from the listing of available ECs.

Concerning the second part of the OP, namely the listing of a cipher suite group, the error shows that something is wrong again in the same part of the code.

[4a6f656c]

X25519 is a function that uses Curve25519 to perform a Diffie-Helman Key Exchange - it is not a generic Elliptic Curve and hence it does not fit into openssl(1)/libcrypto as one. If you believe otherwise, I'll review a diff that changes this behaviour.

Re the second part, libtls != libssl - if you use libtls and specify "secure" ciphers you will get TLSv1.2 ciphers with AEAD and PFS (the equivalent OpenSSL specification is "TLSv1.2+AEAD+ECDHE:TLSv1.2+AEAD+DHE").

Can we close this now?

[hdatma]

The OP is about the existence of a supported curve that does not appear in the actual list of curves.
Curve25519 is not a "generic" EC? So what? List it with the other curves anyway. Each listed curve has a comment that qualifies it. Just add a comment saying whatever it is that you want to say.

Re the second part. I did not use libtls. I just used the default command to list a cipher suite group, using the group specification from the official LibreSSL release note. The OpenBSD community is rather careful when writing documentations.

Can we close this now?

Fuck yeah.

[leonklingele]

@hdatma Curve25519 is a generic curve, but X25519 isn't. X25519 uses Curve25519 as its underlying elliptic curve to perform a DH key exchange. X25519 only uses the X-coordinate, hence its name.