No calendars/contacts found on HTTPS/Radicale server

tonioparis2000

Hello,

I try desperately to make DAVdroid work on a HTTPS/Radicale server.
This server is the personal server of a friend with Apache + TLSv1/TLSv1.1/TLSv1.2 + SHA256 certificate.
On my side, I have Android 4.4.4 and the last release of DAVdroid.

Here is the log file (anonymised) :
http://pastebin.com/wppARQ8U

Thanks in advance for your help.

rfc2822

[debug] PROPFIND on user-given URL failed - EXCEPTION:
javax.net.ssl.SSLHandshakeException: javax.net.ssl.SSLProtocolException: SSL handshake aborted: ssl=0x799fb950: Failure in SSL library, usually a protocol error
error:1407743E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert inappropriate fallback (external/openssl/ssl/s23_clnt.c:744 0x744a2f1c:0x00000000)

There’s a problem with the TLS handshake. Please check your server configuration.

tonioparis2000

Hello rdf2822,

Thank you for your help !

But I did the ssllabs test and the server seems to be perfect !! (look at the result :
0_1455284476335_test-SSL.png)

Do you have an another idea for me ?

Thanks again.

rfc2822

@tonioparis2000 said:

But I did the ssllabs test and the server seems to be perfect !! (look at the result :
0_1455284476335_test-SSL.png)

When looking at the result, I see numerous red lines “Protocol or cipher suite mismatch” in the “Handshake simulation” section. These are the cause of your problem.

tonioparis2000

Hello rfc2822,

@rfc2822 said:

When looking at the result, I see numerous red lines “Protocol or cipher suite mismatch” in the “Handshake simulation” section. These are the cause of your problem.

Indeed, but it’s quite normal that an up-to-date server doesn’t accept connections from old OS/softwares/browsers.

In the test result, I see that Android 4.4.2 is suitable by the server, therefore I assume Android 4.4.4 (mine) as well.

I have two follow-up questions :
Does DAVdroid use the same cipher as Android or its own ?
Is DAVdroid suitable with the cipher of the test (TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) ?

Thanks.

rfc2822

@tonioparis2000 Of course, DAVdroid uses the Android crypto system (and thus it ciphers). However, for Android < 5.0, the allowed ciphers are set explicitly according to NIST SP.800-52r1 to

allow some ciphers which are by default available, but disabled on these Android versions,
disallow some insecure ciphers (which where used with SSLv3, for instance).

You can see a list of allowed ciphers in the linked source code.

Note that this applies only to Android < 5. Since Android 5.0, only SSLv3 is removed from the allowed protocols, but ciphers are not changed.

tonioparis2000

Hello rfc2822 !

I’m back after a time of silence. Thanks for your reply about a month ago !

My friend (the server owner) sent me the ssl_ciphers configuration line in its server :

‘ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!3DES:!MD5:!PSK:!SHA1’;

If I’m reading correctly, no one starts with “TLS_” as in the code you gave (SSLSocketFactoryCompat.java).

However, the server seems to be perfect according to ssllabs.

I don’t understand… If you have again an idea for me…

Thanks !

tonioparis2000

Another possibility would not be an error in the DAVdroid code ?

Indeed, line 66, I read : “TLS_ECHDE_RSA_WITH_AES_128_GCM_SHA256”,
Unlike the other lines, where I read ciphers names with “ECDHE” inside.

But I’m not a developer. Sorry if it’s a wrong path.

rfc2822

@tonioparis2000 said:

Indeed, line 66, I read : “TLS_ECHDE_RSA_WITH_AES_128_GCM_SHA256”,
Unlike the other lines, where I read ciphers names with “ECDHE” inside.

Of course it has to be ECDHE (elliptic-curve Diffie-Hellman ephemeral) and not ECHDE. Will be fixed in future versions (although it only applies to Android 4.x devices). In the meanwhile, I suggest to allow CBC (and not only GCM).