[logback-user] Log data encryption in RollingFileAppender?

Hi I've been looking at the sources of RollingFileAppender, ResilientFileOutputStream, etc. as I'm trying to find a way which allows me to encrypt the log messages before they get written to the underlying file. Still I want to be able to rotate the log files. Any ideas how this can be done elegantly in the current logback framework? Regards, Silvano