What does "end-to-end encryption" refer to?

End-to-end encryption refers to a security method where data is encrypted on the sender's device and can only be decrypted by the recipient's device. This process ensures that the data remains secure and private throughout its transmission, preventing unauthorized access from intermediaries, such as service providers or potential attackers. By implementing this encryption technique, only the intended recipient has the keys to decrypt the information, making it highly effective for maintaining confidentiality.

In contrast, the other choices do not accurately describe end-to-end encryption. The second option incorrectly states that this type of encryption does not require a secret key; in fact, a key is essential for both encryption and decryption processes. The third option misrepresents end-to-end encryption by suggesting that it allows third parties to access data during transmission, which contradicts its primary purpose of safeguarding data from unauthorized access. Lastly, the fourth choice mentions a protocol for securing server communications, which does not capture the essence of end-to-end encryption focusing on securing communications directly between users.