#cryptographic

EPHIPHANY IS UPON YOU. YOUR PILGRIMAGE HAS BEGUN. ENLIGHTENMENT AWAITS.

Cash AOC (2019)

generative photograph from “Nascent Space”

In this sheet presented cryptographic recommendation and libraries to use.

Recommendations:

Key exchange: Diffie–Hellman key exchange with minimum 2048 bits

Message Integrity: HMAC-SHA2

Message Hash: SHA2 256 bits

Assymetric encryption: RSA 2048 bits

Symmetric-key algorithm: AES 128 bits

Password Hashing: Argon2, PBKDF2, Scrypt, Bcrypt

Recommended libraries:

Python: MbedTLS, Libsodium, PyNaCl, Libnacl.

Ruby: Nacl, djb's.

JS: Crypto-js.

Go: Crypto.

Java: Java.security, Javax.crypto.

PHP: Hash, OpenSSL.

C/C++: OpenSSL.

Do not use:

C: random(), rand() ----> getrandom(2) 

Java: java.util.Random() ----> java.security.SecureRandom

PHP: rand() or mt_rand() ----> random_int() or random_bytes()

References:

The Gun-Printing Kids And Energy Drinks (2022)

SYNTHETIC OPTIMISM

Photonic Graph States

The University of Illinois Urbana-Champaign researchers developed a new method for producing complex entangled states of light, which advances the development of distributed quantum computers on near-term hardware. One of quantum photonics' biggest "roadblocks" is the inefficiency of gathering photons from even the most advanced quantum emitters. The team's npj Quantum Information findings address this issue.

The “Lost Photon” issue

Photonic graph states, complicated webs of entangled photons, are essential to measurement-based quantum computation (MBQC) and are employed in quantum computers and communication networks. To construct these states, “deterministic” methods assume that a photon is created, collected, and added to the graph each time an emitter (such as a trapped ion or quantum dot) is excited.

Unfortunately, current hardware is far from perfect. Many modern emitters have photon collection efficiency below 10%. In a deterministic system, losing or not detecting a photon stops the entanglement process and requires a restart. States with dozens or hundreds of photons are practically hard to create because the time needed to form a quantum “graph” grows exponentially with size.

An Anticipated Settlement

Elizabeth A. Goldschmidt, Eric Chitambar, Jianlong Lin, and Maxwell Gold of UIUC suggested the “emit-then-add” strategy. Their plan only adds a photon to the wider entangled graph once its emission and collection are verified, or “heralded,” rather than presuming success.

The researchers explain in the sources that “any failed detection in our scheme simply results in the reinitialization of the emitting spin without any disturbance to the overall graph under construction.” This basic change makes building large graph states polynomial instead of exponential. This substitutes photonic loss for emitter coherence periods and gate fidelities, which are more controlled.

Virtual Graph Hardware Compatibility

A “virtual” graph state is one of the study's most novel ideas. Many applications, like universal MBQC, do not require every photon in a graph to exist simultaneously. Photons are projectively measured shortly after production to depict the “streaming” construction of a large computational resource. This eliminates the need for long-term photonic storage or complex quantum non-demolition (QND) measurements, which most experimental setups cannot provide.

Trapped ion and neutral atom systems are ideal for this technology due to their long-lived internal spin states. Despite their sluggish gate speeds, these systems' coherence times can exceed seconds or hours, providing the continuous “memory” needed for the renowned creation process.

Unlocking Secure Two-Party Computation

Researchers devised a secure two-party computation (MPC) protocol to demonstrate their plan's utility. MPC is a cryptographic task in which Alice and Bob calculate a function on their private data without sharing it.

The UIUC protocol uses a non-collaborating “Referee” and a 12-photon virtual graph state to simplify processing. The parties use Pauli measurements to create “additive homomorphic shares” of their data. The researchers showed that this method protects privacy against malicious actors. Even if they cheat, one party or the referee cannot deduce private information beyond the function's final result.

They also proved their method is robust to experimental failures. The system can retain high fidelity with faulty entangling gates and ineffective photon collection utilizing classical error correction. Even with a pessimistic 10% collecting efficiency, the protocol can reduce error probability by “virtually unlimited reduction” at their recommendations.

Looking Ahead