So I just tried your code, and found the problem. when you assign to $tmp at the top you use double quotes which causes a interpolation of @FP near the end of the string.

changing the double quotes to single quotes fixes that. and if you had used warnings it would have told you.

looking at the demonstration VB it says that if the string isn't a multiple of 8 bytes long it will be truncated to a multiple of 8 bytes so it will need to be padded to guarantee you don't lose anything.

As for the translation. You must be doing it right given that you are getting what you want back. However you should be aware that it isn't UTF-16, and it would be ideal to just store the encrypted logs as binary unless there is a real good reason not to.

so anyway heres full working code, cleaned up a bit.

#!/usr/bin/perl
use warnings;
use strict;

use Crypt::Blowfish;

my $string = 'IPPQY%FF%B3M/%u2030%u2014s%FE%07%8D%1E%u201A%C2%D2%FC%09
+F%u0152%07%CF%u2026nO%5B%D3nZ%5B%u02C6%u0152%01%u201D%CDn%7D%7D%u2018
+F%FB%BA%F12Fm%CB%CF%E9%F1%7E%u2013%u2026%u201E%1B%7E%04h%18b%1EZ%u019
+2H%11%11%A6%FEd%0D%60%EB%u0160%23%216F%0C%23%u2020qs%EA%3A%7B%DC%D6W%
+AF7Y%FE%B8%0D%60%EB%u0160%23%216Fg%0A%BAL0%06%u203Aa%A0H%F9%u017E%A8%
+D6UBt%F4%FAT1%A0%u0178%FC%F0%0El%00%DA%D2%5C%DD%AA%26%7B%20%26%DC%3D%
+13%07%DE1%26%CD%CF%B5%EC%AF%09%10%20LkU%CC%05%E6AgD-N%FB%D9%B0%5B%11o
+%7D%B4%E4%11%F8%13%EAUN%10%u02DC%u201E%u2122i%A2U%0B@%08I%24%C6%04%BB
+%8Dh%D1%0A%F4%7C%AF%3A%FD%B7l%D6%u2026%CDt%D5%5B%B4%u201EW%B6NX%C8%0A
+%A7%F6%D4%B2%07C%0A%3C8%B1%26%D2%EF%E19%17%5D%AF%05%u2122%F1bE%23%u20
+19%u2020%E0%E8%A8%B3%3B%u2026h%E8%5B%u0152%C2%25%B8%DA%27%B5%07%02R%D
+AC%B8E%u2039%D6%01D%u0160%BC%0Au%1F%u2013p%F75%8F%01%1A%E81h%B9%90%u0
+17D%A1%90%FAR%11%EA%u2122%12%DF@FP%7DYY%B2%217V%14%F5%F0%BF%29%A3%C6%
+u0160';

$string = &mime_hex_swap($string);
my $key = &key('Richard');
my $cipher = new Crypt::Blowfish $key;
$string = &unencrypt($cipher, $string);

open (FILE,">file.txt");
print FILE "\n\nText is now \"".$string."\"\n";
close(FILE);
print "\n\nText is now \"".$string."\"\n";
exit();

sub mime_hex_swap {
    my $tmp = shift;
    # wierd shite characters (ISO Latin-1)
    $tmp =~ s/\%u20AC/\%80/gi;
    $tmp =~ s/\%u201A/\%82/gi;
    $tmp =~ s/\%u0192/\%83/gi;
    $tmp =~ s/\%u201E/\%84/gi;
    $tmp =~ s/\%u2026/\%85/gi;
    $tmp =~ s/\%u2020/\%86/gi;
    $tmp =~ s/\%u2021/\%87/gi;
    $tmp =~ s/\%u02C6/\%88/gi;
    $tmp =~ s/\%u2030/\%89/gi;
    $tmp =~ s/\%u0160/\%8A/gi;
    $tmp =~ s/\%u2039/\%8B/gi;
    $tmp =~ s/\%u0152/\%8C/gi;
    $tmp =~ s/\%u017D/\%8E/gi;
    $tmp =~ s/\%u2018/\%91/gi;
    $tmp =~ s/\%u2019/\%92/gi;
    $tmp =~ s/\%u201C/\%93/gi;
    $tmp =~ s/\%u201D/\%94/gi;
    $tmp =~ s/\%u2022/\%95/gi;
    $tmp =~ s/\%u2013/\%96/gi;
    $tmp =~ s/\%u2014/\%97/gi;
    $tmp =~ s/\%u02DC/\%98/gi;
    $tmp =~ s/\%u2122/\%99/gi;
    $tmp =~ s/\%u0161/\%9A/gi;
    $tmp =~ s/\%u203A/\%9B/gi;
    $tmp =~ s/\%u0153/\%9C/gi;
    $tmp =~ s/\%u017E/\%9E/gi;
    $tmp =~ s/\%u0178/\%9F/gi;
    $tmp =~ s/%([0-9A-Fa-f]{2})/chr(hex($1))/eg;
    print "length is now ".length($tmp)."\n";
    return $tmp;
}

sub key {
    my $servername = shift;
    my $key = "AMIPS".$servername.length($servername);
    return $key.reverse($key);
}

sub unencrypt {
    my $cipher = shift;
    my $string = shift;
    print length($string)."\n";
    my $decrypt_data = '';
    die "Incorrect Length" if (length($string) % 8); #Ciphertext MUST 
+be a
                             #multiple of 8
    
    while (my $block = substr($string, 0, 8, ''))  {
        $decrypt_data .= $cipher->decrypt($block);
        print ".";
    }
    return $decrypt_data;
}
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