Encryption

Anyone coming from other languages who's used to stuff like leetcode is likely going to feel a bit silly here. I went with a sequence of <character's ascii value encoded as a string>[<count encoded as a string>] prefaced with a single E in case something needed to be done for empty files too. Turns out something like the Caesar Cipher is more than enough for this problem.

go with a simple encryption/decryption mechanism that uses the Caesar Cipher algorithm. The Caesar Cipher is a substitution cipher that replaces each letter in the plaintext with a letter a fixed number of positions down the alphabet. --- The mode variable specifies whether to encrypt or decrypt the data. --- The shift variable specifies the number of positions to shift the letters in the Caesar Cipher.

It's good that I remembered lesson from Java Syntax zero. You can look, on Java Syntax Zero Level 9, Lesson 6 Bitwise operations, part 2 -> 4.Encryption Rest is like always on this chapter ;)

If you got to this task and panicked like I did "OMG they didn't teach us anything about encryption yet" relax It's not real encryption. It would help if they said "Don't use any of Java's encryption classes. Just convert each byte to another byte, and be able to do this process in reverse."

Make sure you take "-e" and "-d" as arguments, not "e" and "d" !

470

To those who got confused by "encryption/decryption mechanism". You can create your own mechanism:

byte = byte + 1

is an encryption mechanism. The analogous decryption mechanism would be

byte = byte - 1

Cool task :-) Passed for 2nd ( I should have remembered the difference between i++ and ++i :-) )

This task was a lot of fun!

Wow, only 364 people managed to do this task by September 2020. Lowest I've seen so far! I'll leave a small hint: Caesar cipher It might look complicated to do at first, but in fact it is much easier to apply with files than with letters.