Your organization has recently become the victim of an attack against a cryptographic algorithm. The particular attack used all possible keys until a key is discovered that successfully decrypts the ciphertext. Which type of attack occurred?
a. frequency analysis
b. reverse engineering attack
c. ciphertext-only attack
d. brute-force attack
Answer: D. Explanation: A brute-force attack executed against a cryptographic algorithm uses all possible keys until a key is discovered that successfully decrypts the ciphertext. A frequency analysis attack relies on the fact that substitution and transposition ciphers will result in repeated patterns in ciphertext. A reverse engineering attack occurs when an attacker purchases a particular cryptographic product to attempt to reverse engineer the product to discover confidential information about the cryptographic algorithm used. A ciphertext-only attack uses several encrypted messages (ciphertext) to figure out the key used in the encryption process.