Introduction-to-Cryptography Exam Dumps : WGU Introduction to Cryptography HNO1

Skipjack is a symmetric block cipher historically associated with the Clipper chip initiative. Its defining parameters match the question: it operates on 64-bit blocks and uses an 80-bit key. The other options do not fit those exact sizes. Twofish is a 128-bit block cipher with key sizes up to 256 bits. Blowfish is a 64-bit block cipher, but its key size is variable from 32 up to 448 bits and is not fixed at 80 bits as a defining property. Camellia is a 128-bit block cipher with key sizes of 128, 192, or 256 bits. Skipjack’s smaller key size and legacy design make it unsuitable for modern security needs, but the question is purely about identifying the algorithm that matches an 80-bit key and 64-bit blocks. Therefore, the correct answer is Skipjack.

Asymmetric encryption (also called public key cryptography) uses a pair of mathematically related keys: a public key and a private key. One key is used to encrypt, and the other is used to decrypt, which is the defining “different keys” property asked in the question. In the common confidentiality use case, a sender encrypts a message using the recipient’s public key, and only the recipient can decrypt it using their private key. This solves the key distribution problem inherent in symmetric encryption, where both parties must securely share the same secret key in advance. Asymmetric systems also enable digital signatures: the private key signs (creates a signature) and the public key verifies it, providing authenticity and integrity. Symmetric encryption, by contrast, uses the same shared key for both encryption and decryption (even though internal round keys may exist, it is still one shared secret). “Private key” alone is not a full encryption type, and “secure” is a generic description rather than a cryptographic category. Therefore, the correct answer is D. Asymmetric.

A brute-force attack exhaustively tries every possible key or password candidate until the correct one is found. Because it explores the full search space (or a very large portion of it), brute force is often the slowest method, especially when strong keys, long passwords, rate limits, and slow password hashing (bcrypt/Argon2) are used. By contrast, a dictionary attack reduces work by trying only common or likely passwords, often succeeding quickly against weak human-chosen secrets. Rainbow table attacks shift work into precomputation; once a table exists, lookup can be faster than brute-force—though salt and modern hashing defeat them. Birthday attacks are about finding collisions, not necessarily recovering a specific secret, and their expected work is about 2^(n/2) for an n-bit hash, which can be less than brute-force key search in many contexts. Therefore, among the listed options, brute-force generally takes the longest to succeed because it makes the fewest assumptions and does the most total work.