English
Menu

Applied Cryptography

Which of the following correctly pairs the post-quantum cryptography standards published by the US NIST in August 2024 with their types?

  1. AFIPS 203 ML-KEM is a lattice-based signature scheme, FIPS 204 ML-DSA a hash-based key encapsulation mechanism, and FIPS 205 SLH-DSA a symmetric-key cipher
  2. BFIPS 203 ML-KEM, FIPS 204 ML-DSA and FIPS 205 SLH-DSA are all signature schemes with short keys based on problems on elliptic curves
  3. CFIPS 203 ML-KEM is a lattice-based key encapsulation mechanism, FIPS 204 ML-DSA a lattice-based signature scheme, and FIPS 205 SLH-DSA a hash-based signature scheme
Show answer and explanation

Answer: C. FIPS 203 ML-KEM is a lattice-based key encapsulation mechanism, FIPS 204 ML-DSA a lattice-based signature scheme, and FIPS 205 SLH-DSA a hash-based signature scheme

On August 13, 2024, NIST published three FIPS as the first post-quantum cryptography standards. FIPS 203 ML-KEM (originally named CRYSTALS-Kyber) is a key encapsulation mechanism for sharing keys, and FIPS 204 ML-DSA (CRYSTALS-Dilithium) and FIPS 205 SLH-DSA (SPHINCS+) are digital signature schemes. ML-KEM and ML-DSA rest on the difficulty of lattice problems, such as the Module-LWE problem of recovering a secret from a system of linear equations with small errors added. SLH-DSA rests only on the security of hash functions, so its signatures are large and slow, but it is a safeguard in case a weakness is found in lattice problems.

  • A. The roles of key encapsulation mechanism and signature are swapped. SLH-DSA is a hash-based signature scheme, not a symmetric-key cipher.
  • B. Problems on elliptic curves can be solved by Shor's algorithm, so they cannot be the basis of post-quantum cryptography. ML-KEM is a key encapsulation mechanism, not a signature.
  • C. Correct. ML-KEM is used for sharing keys, and ML-DSA and SLH-DSA for signatures.
Practice this topic Back to topic

Books on Applied Cryptography Ad

As an Amazon Associate I earn from qualifying purchases.

More Applied Cryptography questions

  1. Which of the following correctly describes how a key encapsulation mechanism (KEM) such as ML-KEM is used?
  2. Which of the following correctly describes the idea of hybrid key exchange, used during the migration to post-quantum cryptography, that combines X25519 (Diffie–Hellman key exchange using an elliptic curve) with ML-KEM?
  3. One way to think about when to migrate cryptography is "if the number of years x for which data must be kept secret plus the number of years y the migration to new cryptography takes exceeds the number of years z until a quantum computer able to break the cryptography appears, there is already a danger" (Mosca's inequality). With x = 10 years, y = 5 years and z assumed to be 12 years, which of the following is the correct judgment?
  4. Which of the following correctly describes the role of an HSM (hardware security module)?
  5. Let DEK be a data encryption key and KEK a key encryption key. Which of the following correctly describes envelope encryption, as used in cloud storage and elsewhere?

Comparisons in this topic