CISSP Cryptography Practice Test

Steganography is the practice of hiding messages within other files to ensure secrecy. It involves embedding the message within the data of another file, such as a picture, music, or video file. This allows the message to be transmitted without arousing suspicion. Therefore, all of the above options are correct as they can be used to transmit messages protected by steganography.

Using a public key algorithm is slower compared to a symmetric algorithm. Public key algorithms involve complex mathematical calculations and require more computational resources, making them slower in processing data. On the other hand, symmetric algorithms use a single key for both encryption and decryption, resulting in faster processing times.

Diffie-Hellman is a widely used asymmetric key cryptography algorithm. It allows two parties to securely exchange cryptographic keys over an insecure channel. The algorithm is based on the mathematical problem of calculating discrete logarithms in a finite field. Diffie-Hellman provides a way for two parties to generate a shared secret key without actually transmitting it, making it resistant to eavesdropping attacks. It is commonly used in secure communication protocols such as SSL/TLS to establish secure connections between clients and servers.

Asymmetric key cryptography is a method of encryption that uses two different keys, a public key and a private key, to encrypt and decrypt data. It is commonly used for encryption of data to ensure confidentiality and secure communication between parties. It can also be used for access control, where the private key is used to authenticate and grant access to authorized users. Additionally, asymmetric key cryptography can provide nonrepudiation, which means that the sender cannot deny sending a message as their private key is used to sign the message. However, steganography is a different technique that involves hiding information within other media, such as images or audio files, and does not directly involve encryption or asymmetric key cryptography.

The one-time pad is considered unbreakable by brute force because it uses a random key that is as long as the message itself. This key is never reused and is kept completely secret. Each character of the message is encrypted by combining it with the corresponding character of the key using a simple mathematical operation. Since the key is random and used only once, it provides perfect secrecy and makes it impossible for an attacker to determine the original message without knowing the key. In contrast, other cipher systems like AES, DES, and Triple DES can potentially be broken through brute force attacks or other cryptographic attacks.

Polyalphabetic ciphers use multiple alphabets or keys to encrypt the plaintext, making it more difficult for frequency analysis to determine the key. Unlike substitution ciphers, where each letter is replaced with a fixed substitution, polyalphabetic ciphers use different substitutions based on the position of the letter in the plaintext. This adds complexity and randomness to the encryption, making it harder to detect patterns and break the cipher using frequency analysis.

Cryptography supports the core principles of information security, including availability, confidentiality, integrity, and authenticity. Availability ensures that information is accessible to authorized users when needed, while confidentiality ensures that information is protected from unauthorized access. Integrity ensures that information remains unaltered and accurate, while authenticity ensures that the source of the information can be verified. Therefore, the correct answer is authenticity.

The running key cipher is based on modular arithmetic because it involves performing calculations within a finite set of numbers. In this encryption method, each letter of the plaintext is shifted by a corresponding letter from the running key, which is a repeating sequence of characters. The shift is determined by the position of the letters in the alphabet, and if the shift exceeds the number of letters in the alphabet, it wraps around using modular arithmetic. This ensures that the resulting ciphertext remains within the range of the alphabet.