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  "path": "/t/a-cryptography-engineer-s-perspective-on-quantum-computing-timelines/37010#post_7",
  "publishedAt": "2026-04-10T13:12:01.000Z",
  "site": "https://discuss.privacyguides.net",
  "textContent": "There are three quantum algorithms that pose threats to classical encryption:\n\n  1. Shor’s Algorithm\n  2. Grover’s Algorithm\n  3. JVG Algorithm\n\n\n\n**Shor’s algorithm** is the most famous quantum algorithm for breaking public key cryptography. It solves two mathematical problems that hold most internet encryption:\n\n  * Integer factorization (RSA):\n  * Discrete logarithm problem (ECC & DSA)\n\n\n\nA sufficiently powerful quantum computer could break a 2048-bit RSA key or a 256-bit ECC key in hours.\n\nAfter recent optimization in Quantum technology roughly 100,000 – 1 million noisy physical qubits or 1000 - 1400 logical qubits are required to break asymmetric encryption.\n\n**Gover’s algorithm** is the main quantum threat to symmetric encryption and hash functions.\n\nWith Grovers’s algorithm, for symmetric ciphers like AES-256, brute force key search drops to AES-128 security. For cryptographic hashes (e.g., SHA-256), collision or preimage attacks get a similar speedup.\n\nIt does not break the algorithms outright but forces key lengths to roughly double for equivalent security (e.g., AES-256 becomes the new baseline). It is less catastrophic than Shor’s but still requires larger symmetric keys and affects protocols relying on brute-force resistance.\n\nFor a successful attack of Grover’s algorithm (turning 256-bit security to 128-bit or 128-bit to 64-bit) roughly 3000-7000 logical qubits are required.\n\nSo in symmetric encryption if someone is using 256-bit symmetric encryption he is safe for foreseeable future, but 128-bit encryption is in severe danger.\n\n**JVG algorithm** is a new hybrid classical-quantum algorithm explicitly designed as a more resource efficient alternative to Shor’s for integer factorization (and thus RSA/ECC breaking). It was introduced in a preprint by researchers at the Advanced Quantum Technologies Institute (AQTI) and quickly generated headlines about a potential “cybersecurity apocalypse.”\n\nThe paper projects that RSA-2048 could be factored in 11 hours using fewer than 5,000 physical qubits or only 256 logical qubits, a thousand-fold reduction in quantum resources compared to Shor estimates.\n\nBut this is still on paper and only experimented in simulations on tiny numbers so if the claims will hold in real world is still not clear and some independent analysis shows that it has major scalability limitations for large keys.",
  "title": "A Cryptography Engineer’s Perspective on Quantum Computing Timelines"
}