_____ uses at least two different shifts, changing the shift with different letters in the plain text.

Multi-alphabet encryption employs at least two different shifts, altering the shift for different letters in the plaintext. This method enhances security compared to a single shift, as it introduces increased complexity in the encryption process. By utilizing multiple shifts, multi-alphabet encryption can correspond to various encryption schemes, such as the Vigenère cipher, which uses a keyword to determine the shift applied to each letter based on its position in the keyword.

The effectiveness of this method lies in its ability to prevent frequency analysis attacks, which can easily break simpler ciphers that rely on a single shift pattern. Consequently, multi-alphabet encryption creates a more robust encryption framework, making it difficult for unauthorized parties to decipher the message without knowing the specific shifts corresponding to the plaintext characters.