Quantum Security & PQC
Post-quantum cryptography, PQC migration, crypto-agility, cryptographic inventory, CBOM, and practical quantum readiness — from executive mandate to operational deployment.
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Capability D.3: Continuous Operation (Long-Duration Stability)
One of the most critical requirements for a cryptographically relevant quantum computer (CRQC) is continuous operation - the ability to run a complex quantum algorithm non-stop for an extended period (on the order of days) without losing quantum coherence or…
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Capability D.1: Full Fault-Tolerant Algorithm Integration
Imagine a quantum computer that can execute an entire algorithm start-to-finish with errors actively corrected throughout. Full fault-tolerant algorithm integration is exactly that: the orchestration of all components - stable logical qubits, high-fidelity gates, error-correction cycles, ancilla factories, measurements, and…
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Capability D.2: Decoder Performance (Real‑Time Error Correction Processing)
In a fault-tolerant quantum computer, qubits are continuously monitored via stabilizer measurements (producing “syndrome” bits) to detect errors. The decoder is a classical algorithm (running on specialized hardware) that takes this rapid stream of syndrome data and figures out which…
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Capability C.2: Magic State Production & Injection (Non-Clifford Gates)
Magic states are an essential “extra ingredient” for universal quantum computing, often metaphorically likened to a magic catalyst enabling otherwise impossible operations. Quantum algorithms require not only robust qubits and error correction, but also a way to perform non-Clifford gates…
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Capability C.1: High-Fidelity Logical Clifford Gates
Cryptographically Relevant Quantum Computers (CRQCs) will rely on a suite of core capabilities - and high-fidelity logical Clifford gates are among the most essential. This capability refers to performing the fundamental set of quantum logic operations (the Clifford gates: Pauli…
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Capability B.3: Below-Threshold Operation & Scaling
“Below-threshold operation” refers to running a quantum processor at error rates below the critical threshold of a quantum error-correcting code. In simple terms, there is a tipping point in error rates: if each quantum gate and qubit has an error…
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Capability B.2: Syndrome Extraction (Error Syndrome Measurement)
Quantum syndrome extraction - also called error syndrome measurement - is the process of measuring collective properties of qubits to detect errors without destroying the encoded quantum information. It is essentially the sensor mechanism of a quantum error-correcting code, analogous…
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Capability B.1: Quantum Error Correction (QEC)
Quantum Error Correction (QEC) is the first and arguably most critical capability in the roadmap toward a cryptographically relevant quantum computer (CRQC). Without QEC, a large-scale quantum computer cannot reliably perform the billions of operations needed to break modern encryption…
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Shor’s Algorithm: A Quantum Threat to Modern Cryptography
Shor’s Algorithm is more than just a theoretical curiosity – it’s a wake-up call for the security community. By understanding its principles and implications, we can appreciate why the cryptographic landscape must evolve. The goal of this guide is to…
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Grover’s Algorithm and Its Impact on Cybersecurity
Grover’s algorithm was one of the first demonstrations of quantum advantage on a general problem. It highlighted how quantum phenomena like superposition and interference can be harnessed to outperform classical brute force search. Grover’s is often described as looking for…
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The Hidden Subgroup Problem (HSP): One Framework to Break Them All
Every public-key cryptosystem deployed today - RSA, Diffie-Hellman, and elliptic curve cryptography - falls to a single mathematical framework called the Hidden Subgroup Problem (HSP). This is not a coincidence: Shor's algorithm, in each of its variants, works by exploiting…
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Quantum-Safe vs. Quantum-Secure Cryptography
In 2010, I was serving as an interim CISO for an investment bank. During that time, I was already trying to figure out the risks posed by quantum computing. One day, I was approached by a vendor who, with great…
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Qubits: A Brief Introduction for Cybersecurity Professionals
A qubit is the quantum analog of a classical bit – it’s the basic unit of quantum information. However, unlike a classical bit that can only be 0 or 1 at any given time, a qubit can exist in a…
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Bell States: An Introduction for Cybersecurity Professionals
Bell states are a set of four specific quantum states of two qubits (quantum bits) that are entangled. In simple terms, an entangled pair of qubits behaves as one system, no matter how far apart they are. Bell states are…
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Kuperberg’s Algorithm and its Impact on Post-Quantum Cryptography (PQC)
Kuperberg’s algorithm is an impressive quantum algorithmic achievement that expands the boundary of what quantum computers might do beyond the original realm of Shor’s algorithm. It demonstrates that even some non-trivial group problems (like the dihedral hidden subgroup problem) are…
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