This is a package for maemo5/N900. http://maemo.org/packages/view/python3.4/
So for the N900 I would try to compile a new openssl best is to get a different devel package name like libssl1.0-dev. So go with debian package libssl1.0.0 which is a backported 1.0.2 version.
After this I would compile python3-openssl and python3-cryptography. The python3-cryptography should be compiled against the newer libssl which is obvious because it is linked to libssl1.0.0.