Re: [TLS] TLS and KCI vulnerable handshakes

[Viktor Dukhovni <[e-mail]>]

On Mon, Aug 17, 2015 at 12:38:54PM +0000, Peter Gutmann wrote:

> One thing that I'd really like to know is that given the non-PFS (EC)DH suites
> were obviously a dumb idea and barely supported by anything (not just in terms
> of TLS code, no public CA I know of will issue the required X9.42 certs,
> although as the paper points out you can get ECDH ones that can be misused),
> why did OpenSSL add support for them as late as 1.0.2?  Does anyone know why
> they were added?

I can't answer why, but I know what and when:

The cipher-suites that were added to 1.0.2 were fixed finite-field
DH ciphers, not fixed ECDH.

DH-DSS-AES256-GCM-SHA384 TLSv1.2 Kx=DH/DSS   Au=DH   Enc=AESGCM(256) Mac=AEAD
DH-DSS-AES256-SHA       SSLv3 Kx=DH/DSS   Au=DH   Enc=AES(256)  Mac=SHA1
DH-DSS-AES256-SHA256    TLSv1.2 Kx=DH/DSS   Au=DH   Enc=AES(256)  Mac=SHA256
DH-DSS-CAMELLIA256-SHA  SSLv3 Kx=DH/DSS   Au=DH   Enc=Camellia(256) Mac=SHA1
DH-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=DH/RSA   Au=DH   Enc=AESGCM(256) Mac=AEAD
DH-RSA-AES256-SHA       SSLv3 Kx=DH/RSA   Au=DH   Enc=AES(256)  Mac=SHA1
DH-RSA-AES256-SHA256    TLSv1.2 Kx=DH/RSA   Au=DH   Enc=AES(256)  Mac=SHA256
DH-RSA-CAMELLIA256-SHA  SSLv3 Kx=DH/RSA   Au=DH   Enc=Camellia(256) Mac=SHA1
DH-DSS-AES128-GCM-SHA256 TLSv1.2 Kx=DH/DSS   Au=DH   Enc=AESGCM(128) Mac=AEAD
DH-DSS-AES128-SHA       SSLv3 Kx=DH/DSS   Au=DH   Enc=AES(128)  Mac=SHA1
DH-DSS-AES128-SHA256    TLSv1.2 Kx=DH/DSS   Au=DH   Enc=AES(128)  Mac=SHA256
DH-DSS-CAMELLIA128-SHA  SSLv3 Kx=DH/DSS   Au=DH   Enc=Camellia(128) Mac=SHA1
DH-DSS-SEED-SHA         SSLv3 Kx=DH/DSS   Au=DH   Enc=SEED(128) Mac=SHA1
DH-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=DH/RSA   Au=DH   Enc=AESGCM(128) Mac=AEAD
DH-RSA-AES128-SHA       SSLv3 Kx=DH/RSA   Au=DH   Enc=AES(128)  Mac=SHA1
DH-RSA-AES128-SHA256    TLSv1.2 Kx=DH/RSA   Au=DH   Enc=AES(128)  Mac=SHA256
DH-RSA-CAMELLIA128-SHA  SSLv3 Kx=DH/RSA   Au=DH   Enc=Camellia(128) Mac=SHA1
DH-RSA-SEED-SHA         SSLv3 Kx=DH/RSA   Au=DH   Enc=SEED(128) Mac=SHA1
DH-DSS-DES-CBC3-SHA     SSLv3 Kx=DH/DSS   Au=DH   Enc=3DES(168) Mac=SHA1
DH-RSA-DES-CBC3-SHA     SSLv3 Kx=DH/RSA   Au=DH   Enc=3DES(168) Mac=SHA1
DH-DSS-DES-CBC-SHA      SSLv3 Kx=DH/DSS   Au=DH   Enc=DES(56)   Mac=SHA1
DH-RSA-DES-CBC-SHA      SSLv3 Kx=DH/RSA   Au=DH   Enc=DES(56)   Mac=SHA1

The relevant code was added to the 1.0.2 dev branch in Apr of 2012,
backporting said code from the "master" branch where fixed DH
support was enabled in January of 2012.

On a related note, for what it's worth ECDSA certs are constrained
by keyUsage if the extension is present.

-- 
	Viktor.