{"slug": "hybrid-encryption-why-combine-classical-and-post-quantum-cryptography", "title": "Hybrid encryption: why combine classical and post-quantum cryptography", "summary": "A developer has released Quipu, an open-source library that implements hybrid encryption by combining classical and post-quantum algorithms. The library uses X25519 with ML-KEM-1024 for key exchange and Ed25519 with ML-DSA-87 for signatures, targeting NIST security level 5. The developer notes that while the library composes standard primitives, it has not yet undergone an independent cryptographic audit.", "body_md": "When a new cryptographic algorithm appears, a tension shows up: **classical** algorithms such as X25519 or Ed25519 have resisted attacks for years, but are vulnerable to a future quantum computer; **post-quantum** ones such as ML-KEM or ML-DSA resist quantum attacks, but are newer and less tested. Hybrid encryption resolves the tension: **use both at once**.\n\nCombine a classical and a post-quantum algorithm so that the system\n\nonly breaks if both fail simultaneously.\n\nA classical attacker would have to break the post-quantum algorithm; a quantum attacker would have to break the classical one *and* the post-quantum one. You gain security against the future without betting everything on a young algorithm.\n\n**Key exchange (encrypting for a recipient).** You combine:\n\nThe two resulting keys are mixed with a context-bound derivation function (HKDF), so that neither one alone is enough.\n\n**Digital signatures (authenticity).** You combine:\n\nThe message is accepted only if **both** signatures verify — an AND combiner.\n\nThere is a golden rule in cryptography, **Kerckhoffs's principle**: a system must be secure even if the attacker knows its entire design; security lives in the **key**, not in hiding the format. A good hybrid system uses public, audited primitives — XChaCha20-Poly1305 to encrypt, Argon2id to derive keys from passwords, HKDF to separate domains — and **never invents its own cryptography**.\n\n[Quipu](https://xiliux.com/blog/quipu-cifrado-multilenguaje-rust-python-node-go) is a free library implementing exactly this approach for **data at rest**: hybrid X25519 + ML-KEM-1024 encryption, hybrid Ed25519 + ML-DSA-87 signatures, and only verified primitives underneath. It targets NIST security level 5 (CNSA 2.0) and is open source, so anyone can review how it works.\n\nAn honest note: Quipu composes standard primitives, but the composition has not yet passed an\n\nindependentcryptographic audit. For real high-value secrets, that external review is the seal worth waiting for.\n\nThe code is at [github.com/isazajuancarlos/quipu](https://github.com/isazajuancarlos/quipu), AGPL-3.0.", "url": "https://wpnews.pro/news/hybrid-encryption-why-combine-classical-and-post-quantum-cryptography", "canonical_source": "https://dev.to/isazajuancarlos/hybrid-encryption-why-combine-classical-and-post-quantum-cryptography-3hkp", "published_at": "2026-08-30 18:16:42+00:00", "updated_at": "2026-08-30 18:53:06.356885+00:00", "lang": "en", "topics": ["artificial-intelligence", "machine-learning", "large-language-models", "robotics", "autonomous-vehicles"], "entities": ["Quipu", "NIST", "X25519", "ML-KEM-1024", "Ed25519", "ML-DSA-87", "CNSA 2.0", "AGPL-3.0"], "alternates": {"html": "https://wpnews.pro/news/hybrid-encryption-why-combine-classical-and-post-quantum-cryptography", "markdown": "https://wpnews.pro/news/hybrid-encryption-why-combine-classical-and-post-quantum-cryptography.md", "text": "https://wpnews.pro/news/hybrid-encryption-why-combine-classical-and-post-quantum-cryptography.txt", "jsonld": "https://wpnews.pro/news/hybrid-encryption-why-combine-classical-and-post-quantum-cryptography.jsonld"}}