The Digest::MD5 module is not an encryption module but is for creating 'fingerprints' of data. For two-way encryption something like Crypt::RC4 will do the trick e.g

use Crypt::RC4;

my $enc_pw = RC4(seekrit => 'johnr');
my $dec_pw = RC4(seekrit => $enc_pw);

print 'enc_pw = ', unpack( 'H*' => $enc_pw ), "\n";
print 'dec_pw = ', $dec_pw, "\n";

__output__

enc_pw = 344eedff3d
dec_pw = johnr
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