ECC Key Usage ignored with and ECDH(E) ciphers
Xuelei Fan
xuelei.fan at oracle.com
Tue May 23 19:12:10 UTC 2017
Hi Bernd,
What are the JSSE key/trust managers used for the testing ("SunX509" or
"PKIX")?
Thanks & Regards,
Xuelei
On 5/23/2017 7:08 AM, Bernd wrote:
> Hello,
>
> according to RFC 4492 the key usage for ECDHE and ECDH ciphers need to
> be observed in regards to key agreement: When I use ECDH_ECDSA ciphers
> then the server certificate must have the keyAgreement usage. When I use
> ECDHE_ECDSA ciphers then the server certificate must have
> "digitalSignature".
>
> # Note that there is no structural difference between ECDH and ECDSA
> # keys. A certificate issuer may use X.509 v3 keyUsage and
> # extendedKeyUsage extensions to restrict the use of an ECC public key
> # to certain computations [15 <https://tools.ietf.org/search/rfc4492#ref-15>]. This document refers to an ECC key as
> # ECDH-capable if its use in ECDH is permitted. ECDSA-capable is
> # defined similarly.
>
>
> This rule is enforced by the openssl s_client: when the server proposes
> a cipher which does not pass this check it will terminate the connection:
>
> > openssl s_client -cipher ECDHE-ECDSA-AES128-SHA256 -connect
> localhost:1234
> > 1252:error:1411713E:SSL routines:ssl_check_srvr_ecc_cert_and_alg:ecc
> cert not for signing:.\ssl\ssl_lib.c:2512:
> > 1252:error:14082130:SSL routines:ssl3_check_cert_and_algorithm:bad
> ecc cert:.\ssl\s3_clnt.c:3544:
>
> In this case the certificate had key usage:
>
> > [ server-exch ]
> > extendedKeyUsage = serverAuth
> > basicConstraints = CA:FALSE
> > keyUsage = keyAgreement
> > subjectAltName=IP:127.0.0.1,DNS:localhost.
>
> The connect with static ECDH works:
>
> > openssl s_client -cipher ECDH-ECDSA-AES128-SHA256 -connect localhost:1234
> ...
> > SSL-Session:
> > Protocol : TLSv1.2
> > Cipher : ECDH-ECDSA-AES128-SHA256
>
> The other way around, when I use the following key usage:
>
> > [ server-sign ]
> > extendedKeyUsage = serverAuth
> > basicConstraints = CA:FALSE
> > keyUsage = digitalSignature
> > subjectAltName=IP:127.0.0.1,DNS:localhost.
>
> OpenSSL client works this way:
>
> >openssl s_client -cipher ECDH-ECDSA-AES128-SHA256 -connect localhost:1234
> >9916:error:1411713D:SSL routines:ssl_check_srvr_ecc_cert_and_alg:ecc
> cert not for key agreement
>
> >openssl s_client -cipher ECDHE-ECDSA-AES128-SHA256 -connect localhost:1234
> >SSL-Session:
> > Protocol : TLSv1.2
> > Cipher : ECDHE-ECDSA-AES128-SHA256
>
> In both cases however JSSE (OracleJDK8u121 or OpenJDK 9-ea+162) will
> offer both cipher suites and not filter them by key usage capabilties.
> Would you agree this is a bug? And should this also apply to client
> side? I have not tested it with RSA certificates, but I would expect
> this to be the same.
>
> Gruss
> Bernd
>
> PS: config file and openssl commands to create multiple ECC certificates
> used for this test:
> https://gist.github.com/ecki/d66d79bf0cf12872d015804f5edec6e4
>
>
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