jaanhio / cyphers

Encode some strings

ciphers

Write a command line app that encodes some strings.

You don't have to work in order, you can choose to start with the second problem if you want.

If you implement both, make the command line app take an argument for which kind of encoding you want to make.

Morse Code

Given the following alphabet:

{
  a: '.-',
  b: '-...',
  c: '-.-.',
  d: '-..',
  e: '.',
  f: '..-.',
  g: '--.',
  h: '....',
  i: '..',
  j: '.---',
  k: '-.-',
  l: '.-..',
  m: '--',
  n: '-.',
  o: '---',
  p: '.--.',
  q: '--.-',
  r: '.-.',
  s: '...',
  t: '-',
  u: '..-',
  v: '...-',
  w: '.--',
  v: '...-',
  x: '-..-',
  y: '-.--',
  z: '--..'
}

Build a command line morse-code encoder.

Further

Decode the following messages: (hint: command line arguments can take strings with quotes)

... .- -- ..- . .-..    -- --- .-. ... .    .. -. ...- . -. - . -..    -- --- .-. ... .    -.-. --- -.. .

-.-- --- ..- .-.    .. -. ... - .-. ..- -.-. - --- .-. ...    .-.. --- ...- .    -.-- --- ..-

- .... .. ...    .. ...    - .... .    .- -. ... .-- . .-.    - ---    - .... .    ..- .-.. - .. -- .- - .    --.- ..- . ... - .. --- -.    --- ..-.    .-.. .. ..-. .    - .... .    ..- -. .. ...- . .-. ... .    .- -. -..    . ...- . .-. -.-- - .... .. -. --.
....

Caesar cipher

From wikipedia: Caesar cipher is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on.

The transformation can be represented by aligning two alphabets; the cipher alphabet is the plain alphabet rotated left or right by some number of positions. For instance, here is a Caesar cipher using a left rotation of three places, equivalent to a right shift of 23 (the shift parameter is used as the key):

Example:

Plain:    ABCDEFGHIJKLMNOPQRSTUVWXYZ
Cipher:   XYZABCDEFGHIJKLMNOPQRSTUVW

When encrypting, a person looks up each letter of the message in the "plain" line and writes down the corresponding letter in the "cipher" line.

Plaintext:  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
Ciphertext: QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD