encode_decode.py

#ENCRYPTION FUNCTION:
def encode(text,s):
    result = ""
    
    # traverse text
    for i in range(len(text)):
        char = text[i]

        # Encrypt uppercase characters
        if (char.isupper()):
            result += chr((ord(char) + s-65) % 26 + 65)

        # Encrypt lowercase characters
        else:
            result += chr((ord(char) + s - 97) % 26 + 97)

    return result


#DECRYPTION FUNCTION:
def decode(text,s):
    result = ""
    
    # traverse text
    for i in range(len(text)):
        char = text[i]

        # Encrypt uppercase characters
        if (char.isupper()):
            result += chr((ord(char) - s-65) % 26 + 65)

        # Encrypt lowercase characters
        else:
            result += chr((ord(char) - s - 97) % 26 + 97)

    return result