Computing Encryption & Decryption Unit

Index

A computer science term for position

Loop

A sequence of instruction s that is continually repeated until a certain condition is reached

Who was the main leader that decrypted the WW2 Caesar Cipher?

Alan Turing

Shifted alphabet

An alphabet shifted by a certain number

Cipher text

Ciphertext is encrypted text

Decryption

Decrytpion is converting informatiomn into plainTExt

Encirption

Encryption converts information into what is known as Ciphertext.

Caesar Cipher

It is a type of substitution cipher in which each letter in the plaintext is 'shifted' a certain number of places down the alphabet.

Concatenation

It means to link or join words/ numbers together

Strings

Letters, combinations of letters, symbols and even numbers in a code

Can you identify what key has been used? You don't need to crack the whole code! Just find the Key: rozzrksoyysallkzygzutgzallkzkgzotmnkxiaxjygtjcnkegrutmigskgyvojkxcnuygzjucthkyojknkxgtjlxomnzktkjsoyysallkzgcge

Little miss muffet sat on a tuffet eating her curds and whey along came a spider who sat down beside her and frightened miss muffet away

Plain text

Pictures, Video, Audio as well as Text

What can be described as plain Text?

Pictures, Video, Audio as well as Text can all be described as Plaintext.

What was the Caesar Cipher used for in WW2?

The Germans used the Caesar Cipher to pass messages to each other so the British took their Enigma Machine to break their codes

Vignere Cipher

The Vigenere cipher is a plain-text form of encoding that uses alphabetical substitution to encode text.

True Alphabet

The normal alphabet used in the English language

Decrypt

To convert cipher text into plain text

Encrypt

To convert plain text into cipher text

What do we surround strings?

We surround strings with inverted speech marks

How do you allow the user to enter a sentence to be encrypted?

alphabet = key = 3 newMessage = ' ' message = input('Please enter a message') for character in message: position = alphabet.find(character) newPosition = (position + key) % 26 newCharacter = alphabet[newPosition] #print ('The new chracter is:', newCharacter) newMessage += newCharacter print('Your new message is', newMessage)

The code for an encrypted code

trueAlphabet = 'abcdefghijklmnopqrstuvwxyz' shiftedAlphabet = 'defghijklmnoqprstuvwxyzabc' plainText = 'hello' cipherText = '' for letter in trueAlphabet: print(letter) For letter in plainText: position = trueAlphabet.index(letter) shiftedLetter = shiftedAlphabet[position] cipherText = cipherText + shiftedLetter print(cipherText)