The goal of this puzzle is to write a barrel cypher decoder with the smallest code size possible.
The cypher works with a key and a message. The key is a suite of numbers between 1 and 9, the message a space separated list of lower case words. To encrypt a message, we repeatedly travel through the numbers of the key from left to right and then from right to left and shift the letter in the alphabet by the corresponding number.
- key 1595
- message hello world
We start processing the words and using the digits from the key from left to right:
h+1=i, e+5=j, l+9=u, l+5=q
Now that we used all the digits, we do it again from right to left:
o+5=t, the space is discarded, w+9=f, o+5=t, r+1=s
And finally we repeat the process, starting from left to right:
The encrypted message is: ijuqt ftsmi