Bug#905407: ssh-keygen: Use new OpenSSH key format by default

[Luke W Faraone <lfaraone@debian.org>]

Package: openssh-client
Version: 1:7.7p1-3
Severity: wishlist
File: /usr/bin/ssh-keygen

The bcrypt KDF key format was released as part of OpenSSH 6.5 in 2014.
It provides greater resistance against brute-force attacks on encrypted
private keys, and is now widely compatible.

We should use it by default. I'm happy to work on a patch if it would be
accepted.

-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.17.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages openssh-client depends on:
ii  adduser           3.117
ii  dpkg              1.19.0.5+b1
ii  libc6             2.27-5
ii  libedit2          3.1-20180525-1
ii  libgssapi-krb5-2  1.16-2
ii  libselinux1       2.8-1+b1
ii  libssl1.0.2       1.0.2o-1
ii  passwd            1:4.5-1.1
ii  zlib1g            1:1.2.11.dfsg-1

Versions of packages openssh-client recommends:
ii  xauth  1:1.0.10-1

Versions of packages openssh-client suggests:
pn  keychain                              <none>
pn  libpam-ssh                            <none>
ii  monkeysphere                          0.41-1
ii  ssh-askpass-fullscreen [ssh-askpass]  0.3-3.1+b2

-- no debconf information