Certified Encryption Specialist (ECES v3) Free Sample Questions

Perfect Forward Secrecy (PFS) ensures that a session key derived from a set of long-term keys will not be compromised if one of the long-term private keys is compromised in the future. This is achieved by generating new, ephemeral keys for each session and then discarding them. Diffie-Hellman Ephemeral (DHE) and Elliptic Curve Diffie-Hellman Ephemeral (ECDHE) are common key exchange mechanisms that provide PFS.

Counter (CTR) mode turns a block cipher into a stream cipher. It encrypts a counter value which is then XORed with the plaintext. This means each block's encryption/decryption is independent of others, allowing for parallel processing. A corrupted ciphertext block only affects the corresponding plaintext block, preventing error propagation, which is ideal for streaming media over unreliable networks.

Rainbow tables are a specific type of precomputed lookup table used to reverse cryptographic hash functions, typically for cracking password hashes. They are highly effective against unsalted hashes like the ones described.

A rainbow table attack is a classic example of a time-memory trade-off attack. It uses a large amount of storage (memory) to precompute hash chains, which significantly reduces the time required to crack each individual password compared to a brute-force attack.

False. The primary purpose of the S-box is to provide confusion, which obscures the relationship between the key and the ciphertext. Diffusion, which spreads the influence of a single plaintext bit over many ciphertext bits, is primarily provided by the P-box (Permutation-box) in ciphers like DES.

CRYSTALS-Kyber is a lattice-based Key Encapsulation Mechanism (KEM) that NIST has selected as the primary standard for general-purpose public-key encryption and key establishment in the post-quantum era. CRYSTALS-Dilithium and SPHINCS+ are digital signature algorithms, not KEMs.

In the openssl genrsa command, the number of bits for the key size is specified as the last argument without any preceding flag. Therefore, 4096 is the correct value to complete the command.

A mono-alphabetic substitution cipher uses a fixed substitution over the entire message. This preserves the underlying frequency distribution of the original language, making it vulnerable to frequency analysis, as described in the scenario. The Caesar and Atbash ciphers are specific examples of this type.

IPsec Tunnel Mode encrypts the entire original IP packet (header and payload) and encapsulates it within a new IP packet. This is ideal for site-to-site VPNs as it hides the internal network addressing. Transport Mode, in contrast, only encrypts the payload of the original packet, leaving the original IP header intact.

The MD5 algorithm has been cryptographically broken and is known to have practical collision attacks, meaning different inputs can be found that produce the same hash value. For applications requiring collision resistance, such as digital signatures, MD5 is considered insecure and should not be used. SHA-256, SHA-3, and BLAKE2 are all considered secure alternatives.

The main advantage of ECC over RSA is that it offers equivalent cryptographic strength with much smaller key sizes. For example, a 256-bit ECC key provides comparable security to a 3072-bit RSA key. This results in faster computations, lower power consumption, and reduced storage and bandwidth requirements, making ECC ideal for mobile and IoT devices.