PY | 암호화, 복호화

✔️ 예제

key = 'abcdefghijklmnopqrstuvwxyz'

# 평문을 받아서 암호화하고 암호문을 반환한다. 
def encrypt(n, plaintext):
    result = ''

    for l in plaintext.lower():
        try:
            i = (key.index(l) + n) % 26
            result += key[i]
        except ValueError:
            result += l

    return result.lower()

# 암호문을 받아서 복호화하고 평문을 반환한다. 
def decrypt(n, ciphertext):
    result = ''

    for l in ciphertext:
        try:
            i = (key.index(l) - n) % 26
            result += key[i]
        except ValueError:
            result += l

    return result

n = 3
text = 'The language of truth is simple.'
encrypted = encrypt(n, text)
decrypted = decrypt(n, encrypted)
print ('평문: ' ,  text)
print ('암호문: ',  encrypted)
print ('복호문: ' , decrypted)