Research

Watch · narrated whiteboard episodesL3

Symmetric Cryptography and Hashing in the Quantum Era

The post-quantum conversation over-focuses on public-key. The symmetric and hash world also shifts under quantum attack, but far less dramatically, and the exact size of the shift is a clean, quantifiable result. This series works through Grover against block ciphers, quantum search against hash functions, the AES-256 and SHA-384 safe floor, key commitment, and the symmetric primitives quietly holding up the PQC standards themselves. Grounded in Grover, Brassard-Hoyer-Tapp, and the NIST FIPS standards.

Murali Chillakuru·5 episodes
  1. 24 min Episode 1Grover Against Block Ciphers: The Quadratic Speedup, Double the Key Length, and the Parallelization CaveatsA moderator and a cryptography expert examine the quantum threat to block ciphers concretely — the quadratic speedup applied to key search, why doubling the key length restores safety, the parallelization caveats that make the real threat milder, what AES-128 versus AES-256 means in practice, the bottom line, and the stakes for AI agents.
  2. 25 min Episode 2Hash Functions Under Quantum Search: Pre-image versus Collision, and Why Grover Does Not Halve Collision ResistanceA moderator and a cryptography expert examine how quantum computers affect hash functions — the two security properties classically, why pre-image resistance halves under Grover like keys, why collision resistance is not naively halved, the birthday-attack subtlety, the numbers and output sizes to actually use, and the stakes for AI agents.
  3. 25 min Episode 3AES-256 and SHA-384/512 as the Safe Floor: The Concrete Security Margins for the Top LevelsA moderator and a cryptography expert explain how symmetric primitives anchor post-quantum security — the NIST security categories, why the standards define strength by reference to AES and SHA, the concrete top-level margins those give, what the categories mean for choosing parameters, the 'safe floor' idea, practical guidance, and the stakes for AI agents.
  4. 24 min Episode 4Authenticated Encryption and Key Commitment: AEAD Guarantees and the Commitment Gap for AgentsA moderator and a cryptography expert examine a subtle symmetric-crypto weakness that survives into the post-quantum era — what AEAD authenticated encryption guarantees, the key-commitment gap it leaves open, how a commitment attack works, why it matters especially for multi-party and agent systems, the key-committing fix, practical guidance, and the stakes for AI agents.
  5. 25 min Episode 5Where Symmetric Assumptions Are Load-Bearing: Hash-Based Signatures, KDFs, and the PQC Standards ThemselvesIn the symmetric-quantum finale, a moderator and a cryptography expert reveal how much of the post-quantum world rests on symmetric primitives — hash-based signatures resting on hashing alone, the symmetric building blocks inside the lattice standards, the broader symmetric layer, why symmetric is the quiet backbone, the synthesis, and the stakes for AI agents.