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Szyfr Vigenere"a

Opis problemu

Szyfrowanie

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def encrypt_vigenere(message: str, key: str) -> str:
    encrypted = ""
    key_index = 0

    for letter in message:            
        k = ord(key[key_index]) - ord("a")
        encrypted_letter = ord(letter) + k

        if encrypted_letter > ord("z"):
            encrypted_letter = ord("a") + encrypted_letter - ord("z")

        encrypted += chr(encrypted_letter)
        key_index += 1
        key_index %= len(key)

    return encrypted

message = "computerscience"
key = "cat"

encrypted = encrypt_vigenere(message, key)

print(encrypted)

Deszyfrowanie

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def decrypt_vigenere(message: str, key: str) -> str:
    decrypted = ""
    key_index = 0

    for letter in message:
        k = ord(key[key_index]) - ord("a")
        decrypted_letter = ord(letter) - k

        if decrypted_letter < ord("a"):
            decrypted_letter = ord("z") - (ord("a") - decrypted_letter)

        decrypted += chr(decrypted_letter)
        key_index += 1
        key_index %= len(key)

    return decrypted

message = "eogrungrmeixpcx"
key = "cat"

decrypted = decrypt_vigenere(message, key)

print(decrypted)