Hello,
I have a project based on older versions of JForex API, and it worked several months ago. But now it can't authorize and gives me the error:

 ==cut==
2012-06-04 14:44:56.042 INFO  ag - <---"-3"
2012-06-04 14:44:56.043 ERROR ag - Authorization for data feed server failed, sy
stem error
2012-06-04 14:44:59.044 DEBUG ag - Authorizing for data feed server [https://www
6.dukascopy.com/authorization/demo] attempt [2]...
2012-06-04 14:44:59.044 INFO  ag - --->https://www6.dukascopy.com/authorization/
demo/auth?typus=0&munus=datafeed&appello=MYDEMOLOGIN&licentio=3fdf6e70b57eff5b09c
0d66e750e136cc4e47f8b29088648b4a5c2152aee818f&sermo=bdd100c2-8b94-4631-b411-77f9
c0982911
2012-06-04 14:44:59.343 ERROR ag - handshake alert:  unrecognized_name
javax.net.ssl.SSLProtocolException: handshake alert:  unrecognized_name
        at sun.security.ssl.ClientHandshaker.handshakeAlert(Unknown Source)
        at sun.security.ssl.SSLSocketImpl.recvAlert(Unknown Source)
        at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source)
        at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source
)
        at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
        at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
        at sun.net.www.protocol.https.HttpsClient.afterConnect(Unknown Source)
        at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect
(Unknown Source)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown So
urce)
        at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unkn
own Source)
        at com.dukascopy.api.impl.connect.ag.b(Unknown Source)
        at com.dukascopy.api.impl.connect.ag.h(Unknown Source)
        at com.dukascopy.charts.data.datacache.b$c.wV(Unknown Source)
        at com.dukascopy.charts.data.datacache.l.c(Unknown Source)
        at com.dukascopy.charts.data.datacache.l.a(Unknown Source)
        at com.dukascopy.charts.data.datacache.l.a(Unknown Source)
        at com.dukascopy.charts.data.datacache.CurvesDataLoader.c(Unknown Source
)
        at com.dukascopy.charts.data.datacache.cg.run(Unknown Source)
        at com.dukascopy.charts.data.datacache.b.a(Unknown Source)
        at com.dukascopy.charts.data.datacache.w.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)

What should I do to fix the error?

Thanks

Please update the API version.

Are there any easy way of updating? Maybe it's possible to update a single component of the API concerning this specific error?
I have interfaces with C++ code, so full update of API will definitely break the whole system and I'd prefer not to reimplement all of them.

The new API is backwards compatible, hence theoretically you would need to add the new methods to your C++ interfaces and make empty implementations of them.

Could you also check if the connection problem does persist with API version that you are currently using?