encrypt_decrypt.pl
This simple script encrypts and decrypts a file. When the file name ends in .crypt, it is decrypted, otherwise, it is encrypted. When the is encrypted, the script appends .crypt to the filename.
When run, the script needs the environment variable TQ84_CBCCRYPTPASSWORD set.
I have no idea if the script is cryptographically secure. Feedback would be very welcome.
#!/usr/bin/perl
use warnings;
use strict;
use Crypt::CBC;
# ----------------------------------------------------------------------------------
# -key can be any number of characters; the actual key will be derived by
# passing the passphrase through a series of MD5 hash operations. To take
# full advantage of a given block cipher, the length of the passphrase should
# be at least equal to the cipher's blocksize.
#
my $password = $ENV{TQ84_CBCCRYPTPASSWORD} or die "Env Variable TQ84_CBCCRYPTPASSWORD not set";
# ----------------------------------------------------------------------------------
my $filename_in = shift or die "Filename not specified";
my $cipher = Crypt::CBC -> new ( -key => $password,
-cipyer => 'blowfish',
-salt => 1);
my $filename_out;
if ($filename_in =~ /(.*)\.crypt/) {
$filename_out = $1;
print "Decrypting to $filename_out\n";
$cipher -> start('decrypting');
}
else {
$filename_out = "$filename_in.crypt";
print "Encrypting to $filename_out\n";
$cipher -> start('encrypting');
}
die "$filename_out exists" if -f $filename_out;
open (my $f_in , '<', $filename_in ) or die "could not open $filename_in";
open (my $f_out, '>', $filename_out) or die "could not open $filename_in";
binmode $f_in;
binmode $f_out;
my $buf;
while (read($f_in, $buf, 1024)) {
print $f_out $cipher->crypt($buf);
}
print $f_out $cipher->finish;
close $f_in;
close $f_out;
unlink $filename_in or die "Could not delete $filename_in";
print "$filename_in deleted\n";