use Module::Load::Conditional qw[can_load check_install requires];

$Module::Load::Conditional::VERBOSE = 1;
my $crypt_mods = {'Crypt::CBC' => undef,
		  'Crypt::Blowfish' => undef,
		  'Digest::SHA1' => undef,
		  'MIME::Base64' => undef,
		  'Compress::Zlib' => undef,
		  'Crypt::DH' => undef};

if ((  can_load(modules=> {'Math::BigInt::GMP' => undef}, verbose => 1)
    || can_load(modules=> {'Math::BigInt' => undef}, verbose => 1))
    && can_load(modules => $crypt_mods, verbose => 1))
{
    $encryption_avail = 1;
}

print $encryption_avail
      ? "All required crypto modules found and loaded: Encryption available\n"
      : "Encryption disabled: required modules not found\n";


##</code><code>##

sub decrypt
{
    my ($message, $cipher, $key) = @_;
    my ($plaintext, $comptext, $ciphertext, $armortext, $cbc);

    $cbc = Crypt::CBC->new( -key    => $key,
                            -cipher => $cipher);
    $armortext = $$message;
    $ciphertext = decode_base64($armortext) || out ("Unarmor failed!");
    $comptext = $cbc->decrypt($ciphertext) || out ("Decrypt failed!");
    $plaintext = Compress::Zlib::memGunzip($comptext) || out ("Decompress failed!");
    $$message = $plaintext;

    return (1);
}


##</code><code>##

use Module::Loaded;
foreach my $mk ('Compress::Zlib', 'Crypt::Blowfish', 'Crypt::CBC', 'Crypt::DH',
                'Digest::SHA1', 'Math::BigInt::GMP', 'Math::BigInt', 'MIME::Base64')
{
    mark_as_loaded($mk);
}


##</code><code>##

All required crypto modules found and loaded: Encryption available
'Compress::Zlib' already marked as loaded ('/usr/lib/perl5/5.10.0/i686-linux-thread-multi-64int-ld/Compress/Zlib.pm') at ./icbm.conditional-load line 225
'Crypt::Blowfish' already marked as loaded ('/usr/lib/perl5/site_perl/5.10.0/i686-linux-thread-multi-64int-ld/Crypt/Blowfish.pm') at ./icbm.conditional-load line 225
'Crypt::CBC' already marked as loaded ('/usr/lib/perl5/site_perl/5.10.0/Crypt/CBC.pm') at ./icbm.conditional-load line 225
'Crypt::DH' already marked as loaded ('/usr/lib/perl5/site_perl/5.10.0/Crypt/DH.pm') at ./icbm.conditional-load line 225
'Digest::SHA1' already marked as loaded ('/usr/lib/perl5/site_perl/5.10.0/i686-linux-thread-multi-64int-ld/Digest/SHA1.pm') at ./icbm.conditional-load line 225
'Math::BigInt::GMP' already marked as loaded ('/usr/lib/perl5/site_perl/5.10.0/i686-linux-thread-multi-64int-ld/Math/BigInt/GMP.pm') at ./icbm.conditional-load line 225
'Math::BigInt' already marked as loaded ('/usr/lib/perl5/5.10.0/Math/BigInt.pm') at ./icbm.conditional-load line 225
'MIME::Base64' already marked as loaded ('/usr/lib/perl5/5.10.0/i686-linux-thread-multi-64int-ld/MIME/Base64.pm') at ./icbm.conditional-load line 225