Advanced Placement (AP) Computer Science

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Prepare for the AP Computer Science Exam. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

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What is a significant challenge posed by the one-time pad encryption method?

The key must be shorter than the message
The key can never be reused
The method is not secure
The method is based on weak encryption

The correct answer is: The key can never be reused

The one-time pad encryption method is characterized by its use of a key that is as long as the message being encrypted and must be completely random and used only once. This means that for the encryption to maintain its perfect secrecy, each key must never be reused for any other message. If a key is reused, it creates vulnerabilities that can be exploited, as patterns can emerge from repeated use, allowing attackers to deduce information about both messages. This requirement for key uniqueness is a significant challenge because it complicates key management and distribution. Generating truly random keys of sufficient length and ensuring they are securely shared adds complexity, making it difficult to apply in practical situations. Thus, the requirement that the key can never be reused underpins the security strength of the one-time pad while also representing a core challenge in implementing it effectively.