Stretch release is the first version of Debian to feature the
modern branch of GnuPG in the
gnupg package. This brings with it elliptic curve cryptography, better defaults, a more modular architecture, and improved smartcard support. We will continue to supply the
classic branch of GnuPG as gnupg1 for people who need it, but it is now deprecated.
Debug packages are easier to obtain and use in Debian 9
Stretch. A new
dbg-sym repository can be added to the APT source list to provide debug symbols automatically for many packages.
The UEFI (
Unified Extensible Firmware Interface) support first introduced in
Wheezy continues to be greatly improved in
Stretch, and also supports installing on 32-bit UEFI firmware with a 64-bit kernel. The Debian live images now include support for UEFI booting as a new feature, too.