Ceaser Cipher Encryption and Decryption in python | https://youtu.be/0T7wWlst4Io

CeaserCipher.py

'''
author: cYpHeR
Github: cypher-nullbyte
'''
 # -----------------------

 # We assume that our input text is only lowercase string of alphabets without spaced
 # LET US START

def Ceaser_encrypt(text,s):
     result="" # this is for storing end encryptedText
     # Let us visit our input (text) alpha by alpha :)
     for i in range(len(text)):
         char=text[i]
         result+=chr((ord(char)+s-97)%26+97) # don't worry I'll explain this logic
     return result


def Ceaser_decrypt(text, s):
    result = ""  # this is for storing end decrypted
    # Let us visit our input (text) alpha by alpha :)
    for i in range(len(text)):
        char = text[i]
        result += chr((ord(char) - s +26- 97) % 26 + 97)  # this is what we are interested in
        # In encryption we added the shift 's' here we will be doin the reverse :)
        # Why I've added 26?
        # Because we have modulo 26 and it is wrap around..
    return result
if __name__=="__main__":
    Key=int(input("Enter Key/Shift: "))
    # Plain=input() 
    # BUt hold on, we are gonna consider only lowercase alphabets as text into our 'Ceaser_encrypt'.
    # let us lowercase 'Plain' and split it over spaces into list and join back.
    # in other words let us remove all spaces from 'Plain' and lowercase everything
    Plain=''.join(input("PlainText : ").lower().split())
    CipherText=Ceaser_encrypt(Plain,Key)
    print("CipherText: ",CipherText)
    
    # let us now try to decrypt it :)
    print("DecipheredText: ",Ceaser_decrypt(CipherText,Key))
    # It is working.. LEt us discuss this logic

https://www.youtube.com/watch?v=0T7wWlst4Io&feature=youtu.be