Subj : Post-Quantum Secure Encryption
To   : All
From : warmfuzzy
Date : Mon Aug 03 2026 17:40:12

The algorithms currently recognized as secure against post-quantum decryption 
are those that rely on mathematical problems which are believed to be hard for 
both classical and quantum computers to solve. Unlike traditional public-key 
systems such as RSA and elliptic-curve cryptography, which can be broken 
efficiently by a large-scale quantum computer using Shor's algorithm, the new 
post-quantum standards are based on different mathematical foundations. The 
United States National Institute of Standards and Technology (NIST) finalized 
its first set of post-quantum cryptography standards on August 13, 2024, 
establishing three primary algorithms for widespread use.

The first standard is ML-KEM, formerly known as CRYSTALS-Kyber. This is a 
module-lattice-based key encapsulation mechanism designed for general 
encryption and key exchange. It allows two parties to establish a shared 
secret key over an insecure channel, replacing algorithms like Diffie-Hellman 
or RSA key transport. ML-KEM is considered secure because it relies on the 
hardness of solving certain lattice problems, specifically the Module Learning 
With Errors problem, which has not been shown to be vulnerable to quantum 
attacks.

For digital signatures, NIST standardized two distinct algorithms to provide 
flexibility for different use cases. The primary signature standard is ML-DSA, 
formerly known as CRYSTALS-Dilithium. Like ML-KEM, this is a 
module-lattice-based scheme. It is designed to be efficient and suitable for 
most general-purpose digital signing needs, such as authenticating software 
updates or securing TLS connections. Its security is also based on lattice 
problems that are resistant to quantum computation.

The second signature standard is SLH-DSA, formerly known as SPHINCS+. This is 
a stateless hash-based signature scheme. Unlike the lattice-based options, its 
security relies entirely on the properties of cryptographic hash functions, 
which are believed to be much more resilient to quantum attacks than 
number-theoretic problems. While hash-based signatures generally produce 
larger signature sizes and can be slower than lattice-based ones, they offer a 
very conservative security assumption that does not depend on the complex 
mathematics of lattices. This makes SLH-DSA an important backup option in case 
weaknesses are discovered in lattice-based cryptography in the future.

In addition to these three primary standards, NIST has selected FALCON as an 
alternative lattice-based signature algorithm for situations where smaller 
signature sizes are critical, although it is not yet part of the initial 
mandatory federal standards. It is worth noting that symmetric-key algorithms 
like AES and hash functions like SHA-2 and SHA-3 are not completely immune to 
quantum speedups but remain secure if their key lengths or output sizes are 
doubled to counter Grover's algorithm, a quantum search algorithm. Therefore, 
while asymmetric encryption and signatures require a complete switch to these 
new post-quantum algorithms, symmetric cryptography primarily requires 
adjusting key sizes to maintain security levels against quantum adversaries. 
Organizations are currently advised to begin migrating their systems to these 
NIST-standardized algorithms to protect data against future threats posed by 
quantum computing.

Cheers!
-warmfuzzy/SilentPartner

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