--- title: Signal Protocol and Post-Quantum Ratchets | daily.dev description: Signal introduces the Sparse Post Quantum Ratchet (SPQR), a new cryptographic protocol that protects messaging against future quantum computing threats. The... canonical: https://daily.dev/posts/signal-protocol-and-post-quantum-ratchets-37ajp56j2 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Signal Protocol and Post-Quantum Ratchets | daily.dev og:description: Signal introduces the Sparse Post Quantum Ratchet (SPQR), a new cryptographic protocol that protects messaging against future quantum computing threats. The... og:url: https://daily.dev/posts/signal-protocol-and-post-quantum-ratchets-37ajp56j2 og:image: https://api.daily.dev/og/posts/37aJP56J2.png og:image:alt: Signal Protocol and Post-Quantum Ratchets og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Signal Protocol and Post-Quantum Ratchets **[Hacker News](https://daily.dev/sources/hn)** · 30 min read · 5 upvotes · 0 comments ## Summary Signal introduces the Sparse Post Quantum Ratchet (SPQR), a new cryptographic protocol that protects messaging against future quantum computing threats. The Triple Ratchet combines SPQR with Signal's existing Double Ratchet to maintain forward secrecy and post-compromise security while adding quantum resistance. The protocol uses ML-KEM key encapsulation, erasure codes for efficient data transmission, and careful state machine design to minimize bandwidth overhead. Signal implements formal verification through ProVerif and F* to ensure correctness, and deploys the upgrade transparently with automatic downgrade support for backward compatibility. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#cryptography](https://daily.dev/tags/cryptography), [#encryption](https://daily.dev/tags/encryption), [#quantum-computing](https://daily.dev/tags/quantum-computing), [#security](https://daily.dev/tags/security) [View this post on daily.dev](https://daily.dev/posts/signal-protocol-and-post-quantum-ratchets-37ajp56j2) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Signal Protocol and Post-Quantum Ratchets","url":"https://daily.dev/posts/signal-protocol-and-post-quantum-ratchets-37ajp56j2","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/signal-protocol-and-post-quantum-ratchets-37ajp56j2"},"datePublished":"2025-10-02T17:12:44.698Z","dateModified":"2026-03-15T06:37:36.314Z","description":"Signal introduces the Sparse Post Quantum Ratchet (SPQR), a new cryptographic protocol that protects messaging against future quantum computing threats. 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