FS#405 - openvpn-mbedtls can not verify certificate

[openwrt-bot]

duvi:

On the same configuration, same system, same certificates, openvpn-mbedtls can not verify the certificate, but openvpn-openssl is working ok.

Notice the "??=vma", how openvpn-mbedtls doesn't recognize the "name" field in the certificate. Maybe that is the problem.

I have the same suboptions enabled in "make menuconfig" in both cases.

openvpn-mbedtls:
Fri Jan 13 23:05:58 2017 TCP/UDP: Preserving recently used remote address: [AF_INET]my.ser.ver.ip:1194
Fri Jan 13 23:05:58 2017 Socket Buffers: R=[163840->163840] S=[163840->163840]
Fri Jan 13 23:05:58 2017 UDP link local (bound): [AF_INET][undef]:1194
Fri Jan 13 23:05:58 2017 UDP link remote: [AF_INET]my.ser.ver.ip:1194
Fri Jan 13 23:05:58 2017 TLS: Initial packet from [AF_INET]my.ser.ver.ip:1194, sid=75e238e0 c51819f1
Fri Jan 13 23:05:58 2017 VERIFY ERROR: depth=0, subject=C=HU, ST=BA, L=Pecs, O=Duvinet, OU=vma, CN=my.server.dns, ??=vma, emailAddress=myemail@mydomain.hu: The certificate is signed with an unacceptable key (eg bad curve, RSA too short).
Fri Jan 13 23:05:58 2017 TLS_ERROR: read tls_read_plaintext error: X509 - Certificate verification failed, e.g. CRL, CA or signature check failed
Fri Jan 13 23:05:58 2017 TLS Error: TLS object -> incoming plaintext read error
Fri Jan 13 23:05:58 2017 TLS Error: TLS handshake failed
Fri Jan 13 23:05:58 2017 SIGUSR1[soft,tls-error] received, process restarting

openvpn-openssl:
Tue Jan 17 09:36:06 2017 TCP/UDP: Preserving recently used remote address: [AF_INET]my.ser.ver.ip:1194
Tue Jan 17 09:36:06 2017 Socket Buffers: R=[163840->163840] S=[163840->163840]
Tue Jan 17 09:36:06 2017 UDP link local (bound): [AF_INET][undef]:1194
Tue Jan 17 09:36:06 2017 UDP link remote: [AF_INET]my.ser.ver.ip:1194
Tue Jan 17 09:36:06 2017 TLS: Initial packet from [AF_INET]my.ser.ver.ip:1194, sid=3fc0a62c be2ce0f4
Tue Jan 17 09:36:06 2017 VERIFY OK: depth=1, C=HU, ST=BA, L=Pecs, O=Duvinet, OU=vma, CN=my.server.dns, name=vma, emailAddress=myemail@mydomain.hu
Tue Jan 17 09:36:06 2017 Validating certificate key usage
Tue Jan 17 09:36:06 2017 ++ Certificate has key usage 00a0, expects 00a0
Tue Jan 17 09:36:06 2017 VERIFY KU OK
Tue Jan 17 09:36:06 2017 Validating certificate extended key usage
Tue Jan 17 09:36:06 2017 ++ Certificate has EKU (str) TLS Web Server Authentication, expects TLS Web Server Authentication
Tue Jan 17 09:36:06 2017 VERIFY EKU OK

[openwrt-bot]

nbd:

It looks like the problem is this:
"The certificate is signed with an unacceptable key (eg bad curve, RSA too short)."

Are you still using an RSA-1024 certificate? mbedtls refuses those for security reasons

[openwrt-bot]

duvi:

Thanks for the tip, I regeneretad the certificates with RSA 2048, and it's working ok now.
I just wonder, why openssl still accepts it.
Anyway, we can close this.

[openwrt-bot]

ianchi:

Hi, I'm having the same issue after switching from openssl to mbedtls.
I regenerated certificates with 2048length, and now the CA cert is ok, but now I get get a validation error on the client cert:
"The certificate is signed with an unacceptable hash."

On the client side (running an openssl version) the server certificate is successfully validated

Any ideas on what can be happening?

[openwrt-bot]

ianchi:

Just to share the solution that worked for me to switch to mbedtls:

• change to RSA 2048
• change certificate digest from MD5 to SHA256 (use option "default_md = sha256").

The default digest used by easy-rsa key generation scripts was "md5", and it was rejected by mbedtls.