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Foundational Cryptography in SPARK
AdaCore's M. Anthony Aiello reports that AI, without direct human intervention, wrote SPARK specifications and SPARK Platinum-proven implementations of AES-128/192/256, SHA-256 and HMAC-SHA-256 from the NSA's Cryptol specs in the Foundation repository, backed by equivalence proofs (including Galois SAW), 100% MC/DC spec-based tests, performance comparisons against Rust, and a breakdown of agent and tool time.
15 min · 3,440 words
V12's Rick de Jager shows that several PDF implementations advertising AES-256 generate file keys from tiny or predictable state: in MuPDF before 1.28.5 only 9 bits of a time-seeded drand48 state affect the key, Foxit derives keys from time-based randomness, and OpenPDF/iText seed RC4 from a timestamp plus JVM free memory, enabling passwordless decryption. Issues were disclosed (MuPDF fixed) and decryptors published.
6 min · 1,295 words
Choose Your Backend: Three TLS Bugs in GoAhead
FoxIO researcher Sébastien Féry details three independent bugs in the TLS integrations of GoAhead, an embedded web server in hundreds of millions of IoT, firewall and industrial devices: revoked client certificates accepted on OpenSSL builds (CVSS 9.1), a chain-depth bypass on LibreSSL's legacy verifier, and an Mbed TLS typo that shrinks a 2048-bit DH modulus to one byte; GoAhead 6.1.1 fixes them.
14 min · 3,243 words
Eight Bits of Trust; eMudhra's CA keys cracked in milliseconds
Scott Helme explains how eight eMudhra intermediate CA private keys were recoverable from their public certificates in under a second because the keys were trivially small, how Chrome and Mozilla responded with CRLSet/OneCRL blocks and root removal, why the compromise cannot be contained, and what site operators should do now.
7 min · 1,642 words
The NIST Elliptic Curves Seeds Bounty Has Been Claimed
Filippo Valsorda reports that the long-mysterious seeds of the NIST P-curves were not hashes of forgotten sentences but drand48 output seeded with UNIX timestamps from 1997–98. A team from Anthropic solved it and claimed his bounty, donating the tripled $36,864 prize to ISRG, the non-profit behind Let's Encrypt.
5 min · 1,181 words
Claude reveals ECDSA curve origins
Anthropic's Frontier Red Team explains how Claude helped uncover how the unexplained seeds behind the NIST ECDSA curves in FIPS 186-2 were generated: from timestamps fed into a standard random number generator, not a hidden passphrase. The post covers how it was found, recovered base points, open questions, the bounty, and code to reproduce the seeds.
10 min · 2,406 words
(Post-Quantum) Cryptographic Right Answers
Filippo Valsorda updates the "Cryptographic Right Answers" tradition (Percival, Ptacek, Latacora) for the accelerated post-quantum transition, giving developers concrete recommendations for encryption, key exchange, signatures, hashing, passwords, TLS and more.
17 min · 4,016 words
Alin Tomescu surveys concerning attacks on trusted execution environments such as Intel SGX and AMD SEV, and argues that teams should reconsider how, and whether, they deploy TEE-based applications given how hard hardware security claims are to verify.
5 min · 1,057 words
Timestamping a giant record of the Web
Project Timestamper announces that it has cryptographically timestamped all 339 billion web page snapshots in the Common Crawl archive, committing hashes of about 134 million index blocks to the Bitcoin blockchain via OpenTimestamps so any later alteration of a capture made before 2026-09-26 is detectable, with a one-command verification tool.
2 min · 467 words
SequenceHash: multihashing for the rest of us
Multihashing is one of those cryptographic tasks that’s easy not to think about too much. This is unfortunate, because multihashing is a common stumbling point when cryptographers try to use hashes.
13 min · 2,942 words
Connecting Agents with Cryptography
Liam Horne explores how MPC, FHE, and TEEs could let personal agents cooperate—matching calendars, comparing salaries, or finding bug-fix peers—without sharing private context, and who might pay for that shared computation.
5 min · 1,096 words
Thomas Ahle presents a technique for evaluating polynomials in roughly half the multiplications that Horner's method requires, by preprocessing the coefficients offline. An interactive tool lets users input a polynomial and field to see the optimised evaluation chain.
1 min · 234 wordsagent-written
Claude Fable 5.1 Solves the Cyphral DistichWe gave Claude Fable 5.1 an open task: solve an unsolved 370-year-old cipher. It solved it within a day.
Vals AI reports that Claude Fable 5.1 solved the Cyphral Distich, a 370-year-old cryptogram by Sir Thomas Urquhart that had resisted solution for centuries. The model also cracked Urquhart's larger Cyphral Octastich, recovering nearly the full plaintext using the original book as the cipher key.
1 min · 262 wordsagent-written
The Gold-Bug: Edgar Allan Poe's story that taught me about cryptography
Sudheer Apte recalls how Edgar Allan Poe's short story The Gold-Bug, read in middle school in India, introduced him to cryptography. He explains how Poe came to write the 1843 story, how its substitution cipher is cracked with letter-frequency analysis, the link to Claude Shannon, and why many reprints of the cipher contain errors.
4 min · 881 words
Why I Wrote PGP Part of the Original 1991 PGP User's Guide (updated in 1999) "Whatever you do will be insignificant, but it is very important that you do it." -Mahatma Gandhi It's personal. It's private. And it's no one's business but yours. You may be planning a political campaign, discussing your taxes, or having an illicit affair. Or you may be communicating with a political dissident in a repressive country. Whatever it is, you don't want your private electronic mail (email) or confidential documents read by anyone else. There's nothing wrong with asserting your…
8 min · 1,951 words