This package generates a lintian warning:

N: Processing binary package yubikey-personalization-gui (version 3.1.22-1, arch amd64) ...
I: yubikey-personalization-gui: hardening-no-fortify-functions usr/bin/yubikey-personalization-gui
N:
N:    This package provides an ELF binary that lacks the use of fortified libc
N:    functions. Either there are no potentially unfortified functions called
N:    by any routines, all unfortified calls have already been fully validated
N:    at compile-time, or the package was not built with the default Debian
N:    compiler flags defined by dpkg-buildflags. If built using
N:    dpkg-buildflags directly, be sure to import CPPFLAGS.
N:
N:    NB: Due to false-positives, Lintian ignores some unprotected functions
N:    (e.g. memcpy).
N:
N:    Refer to https://wiki.debian.org/Hardening and
N:    https://bugs.debian.org/673112 for details.
N:
N:    Severity: normal, Certainty: wild-guess
N:
N:    Check: binaries, Type: binary, udeb

I have read https://wiki.debian.org/Hardening but haven't been able to
fix this.

Running blhc on the buid log produces nothing:

jas@latte:~/src/yubikey-personalization-gui-dpkg$ blhc ../yubikey-personalization-gui_3.1.22-1_amd64.build
jas@latte:~/src/yubikey-personalization-gui-dpkg$

Indeed hardening-check complains about fortify source functions:
jas@latte:~/src/yubikey-personalization-gui-dpkg$ hardening-check /usr/bin/yubikey-personalization-gui
/usr/bin/yubikey-personalization-gui:
 Position Independent Executable: yes
 Stack protected: yes
 Fortify Source functions: no, only unprotected functions found!
 Read-only relocations: yes
 Immediate binding: yes
jas@latte:~/src/yubikey-personalization-gui-dpkg$

Please help if you can!

/Simon

Dear submitter,

as the package yubikey-personalization-gui has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1014276

The version of this package that was in Debian prior to this removal
can still be found using http://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)