This is Crypt::Keys.

Crypt::Keys contains read/write routines for a variety of
public and private key algorithms; each algorithm can be
encoded in several different formats. For example, you might
have a private RSA key file, encoded in PEM format.

In order to determine the modules you'll need on your system,
you must select the types of encoding you will be using. Please
choose the encodings you'd like to use from the following list
("All" is the default).

    [1] PEM
    [2] SSH
    [3] All

Enter your choices for encoding(s), separated by spaces: [3] 3


Checking for required modules

Crypt::CBC ...................ok
Math::Pari ...................** FAILED **
Crypt::DES ...................ok
MIME::Base64 .................ok
Convert::PEM .................** FAILED **
Digest::MD5 ..................ok
Data::Buffer .................ok
Crypt::Keys depends on several external modules for functionality.
Some of these modules can not be found on your system; they can be
installed automatically for you. To do so will require loading the
CPAN shell, which may require you to be running as root. Answer 'n' to
each of the following questions if you'd rather not install any
needed modules right now; note, however, that you'll still need to
install them to use Crypt::Keys.

Math::Pari (ver. 2.001804) not installed/out of date. Install (y/n)? [y] y
CPAN: Storable loaded ok (v2.18)
Going to read C:\cpanrun\build\5-10-0\cpan\Metadata
  Database was generated on Tue, 08 Jan 2008 11:37:51 GMT
Running install for module 'Math::Pari'
Running make for I/IL/ILYAZ/modules/Math-Pari-2.010709.tar.gz
CPAN: LWP::UserAgent loaded ok (v2.036)
CPAN: Time::HiRes loaded ok (v1.9711)
Fetching with LWP:
  http://ppm.activestate.com/CPAN/authors/id/I/IL/ILYAZ/modules/Math-Pari-2.010709.tar.gz
CPAN: YAML loaded ok (v0.66)
CPAN: Digest::SHA loaded ok (v5.44)
Fetching with LWP:
  http://ppm.activestate.com/CPAN/authors/id/I/IL/ILYAZ/modules/CHECKSUMS
Checksum for C:\cpanrun\build\5-10-0\cpan\sources\authors\id\I\IL\ILYAZ\modules\Math-Pari-2.010709.tar.gz ok
CPAN: Archive::Tar loaded ok (v0.07)
Will not use Archive::Tar, need 1.00

CPAN.pm needs either the external programs tar, gzip and bzip2
installed. Can't continue.