Create a Caesar encryption¶
Create a Caesar encryption.
Note:
In cryptography, a Caesar cipher, also known as Caesar’s cipher,
the shift cipher, Caesar’s code or Caesar shift, is one of the
simplest and most widely known encryption techniques.
It 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 method is named after Julius Caesar, who used it in his
private correspondence.
def caesar_encrypt(realText, step):
outText = []
cryptText = []
uppercase = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z']
lowercase = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
for eachLetter in realText:
if eachLetter in uppercase:
index = uppercase.index(eachLetter)
crypting = (index + step) % 26
cryptText.append(crypting)
newLetter = uppercase[crypting]
outText.append(newLetter)
elif eachLetter in lowercase:
index = lowercase.index(eachLetter)
crypting = (index + step) % 26
cryptText.append(crypting)
newLetter = lowercase[crypting]
outText.append(newLetter)
return outText
# test
code = caesar_encrypt('abc', 2)
print(code) # ['c', 'd', 'e']