Certified in Risk and Information Systems Control (CRISC) Practice Test

The one-time pad is considered foolproof due to its unique characteristics that provide absolute security when used correctly. This technique involves creating a key that is completely random, at least as long as the message itself, used only once, and shared securely between the two parties. When the key is combined with the plaintext message, it produces ciphertext in such a way that if the key is truly random and used only a single time, the ciphertext will not reveal any information about the plaintext, thus making it theoretically unbreakable.

This level of security stems from the principle that there is an equal probability of the resulting ciphertext for each possible plaintext, meaning an attacker cannot gain any knowledge even if they capture the ciphertext. However, the one-time pad does have practical challenges, such as key distribution and management, which often limits its practical application.

In contrast, while block ciphers and algorithms like the Advanced Encryption Standard (AES) provide strong encryption, they still rely on the complexity of the algorithm and the strength of the key, which can be vulnerable to certain types of attacks if not implemented correctly. Public Key Infrastructure (PKI) adds a different layer of security through asymmetric cryptography, but it relies on trust in the certificate authorities and is not inherently foolproof like