From e4508767cb48be672ec35bbd4bc7d1645640af4e Mon Sep 17 00:00:00 2001
From: Jörg Sommrey <28217714+jo-37@users.noreply.github.com>
Date: Sun, 19 Mar 2023 15:20:59 +0100
Subject: Challenge 025 task 2

---
 challenge-025/jo-37/perl/ch-2.pl | 51 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100755 challenge-025/jo-37/perl/ch-2.pl

diff --git a/challenge-025/jo-37/perl/ch-2.pl b/challenge-025/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..43525ac1c2
--- /dev/null
+++ b/challenge-025/jo-37/perl/ch-2.pl
@@ -0,0 +1,51 @@
+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use warnings FATAL => 'all';
+use Data::Dump qw(dd pp);
+use experimental qw(signatures postderef);
+
+our ($plain, $cipher, $decrypt);
+
+die <<EOS unless $plain && $cipher && @ARGV == 1;
+usage: $0 -plain=PLAIN -cipher=CIPHER [-decrypt] TEXT
+
+-plain=PLAIN
+    use PLAIN as the plain alphabet
+ 
+-cipher=CIPHER
+    use CIPHER as the cipher alphabet
+
+-decrypt
+    decrypt TEXT
+
+TEXT
+    en- or decrypt TEXT
+
+EOS
+
+
+### Input and Output
+
+say chaocipher($plain, $cipher, shift, $decrypt);
+
+
+### Implementation
+
+sub chaocipher ($plain, $cipher, $text, $decrypt) {
+	my @keys = ([split //, $plain],
+                [split //, $cipher]);
+
+    my $result;
+    while ($text) {
+        my $char = substr $text, 0, 1, '';
+        my $ind;
+        for ($ind = 0; $keys[!!$decrypt][$ind] ne $char; $ind++) {}
+        $result .= $keys[!$decrypt][$ind];
+        $keys[0] = [($keys[0]->@[$ind + 1 .. 25, 0 .. $ind])[0, 1, 3 .. 13, 2, 14 .. 25]];
+        $keys[1] = [($keys[1]->@[$ind .. 25, 0 .. $ind - 1])[0, 2 .. 13, 1, 14 .. 25]];
+
+    }
+    $result;
+}
-- 
cgit