# Matthew Green Some random thoughts about crypto. Notes from a course I teach. Pictures of my dachshunds. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## How AI Could Affect Law Enforcement Access to Encrypted Data DevFeed: [How AI Could Affect Law Enforcement Access to Encrypted Data]() Original publisher: [Read original article]() Author: Matthew Green Published: 2026-08-14T20:17:59Z Content type: opinion Language: en Sources: [Matthew Green]() Topics: [Artificial Intelligence](), [Security](), [Encryption](), [End-to-End Encryption]() Tags: [ai](), [encryption](), [security](), [uncategorized]() ### AI overview The author argues that AI could make software sufficiently secure that U.S. intelligence and law-enforcement agencies lose substantial access to data. The post places this concern in the context of smartphones and the adoption of encrypted storage and end-to-end encrypted messaging. ### Source excerpt I'm coming down from spending a few days at Usenix Security, right here in my hometown of Baltimore. This means that my days have been taken up with two kinds of conversation: first, explaining to colleagues why Baltimore isn't actually like The Wire. And second, trying not to talk about AI. Here I'm going to ... Continue reading Everything is about to "go dark" -> ## Some thoughts about Anthropic's new cryptanalysis results DevFeed: [Some thoughts about Anthropic's new cryptanalysis results]() Original publisher: [Read original article]() Author: Matthew Green Published: 2026-07-29T14:23:30Z Content type: opinion Language: en Sources: [Matthew Green]() Topics: [Cryptography](), [Claude](), [anthropic](), [Post-Quantum](), [Algorithm]() Tags: [academics](), [ai](), [algorithm](), [anthropic](), [artificial-intelligence](), [attacks](), [chatgpt](), [claude](), [llm](), [post-quantum](), [research](), [security](), [technology](), [thoughts]() ### AI overview The article offers commentary on two cryptanalysis results published by Anthropic and produced by Claude Mythos: an attack on the proposed HAWK post-quantum signature scheme and an improved attack on reduced-round AES. It emphasizes that the HAWK attack targets a non-deployed, non-standardized scheme and demonstrates a weakness using a weakened challenge instance. ### Source excerpt Yesterday Anthropic published two new cryptanalysis results, both outputs of Claude Mythos, their (still) unreleased advanced model. The first of these results attacks a signature scheme called HAWK, while the second is an improved attack against reduced-round AES. Anthropic also released a blog post describing the research process that produced these results. A few people ... Continue reading Some thoughts about Anthropic's new cryptanalysis results -> ## The future of Siri, or: why private inference isn't private enough DevFeed: [The future of Siri, or: why private inference isn't private enough]() Original publisher: [Read original article]() Author: Matthew Green Published: 2026-06-09T19:00:02Z Content type: opinion Language: en Sources: [Matthew Green]() Topics: [Artificial Intelligence](), [Inference](), [Google](), [data](), [context](), [private cloud]() Tags: [ai](), [apple](), [artificial-intelligence](), [chatgpt](), [cloud](), [context](), [data](), [gemini](), [google](), [inference](), [llm](), [privacy](), [security](), [stateless](), [technology]() ### AI overview The article examines Apple's plans to add frontier-model capabilities to Siri using Google Gemini, Google Confidential Inference, and Apple's Private Cloud Compute. It explains the privacy rationale for using device context and describes PCC's stateless, hardware-protected design, while arguing that the expanded system's reliance on Google infrastructure remains technically vague. ### Source excerpt Yesterday Apple announced a big step towards deploying real AI in their Siri ecosystem. In most ways this is good and inevitable: Siri is one of the world's most widely-used voice agents, and it would be good if it didn't suck. The idea that Apple would boost its capabilities with frontier models wasn't so much ... Continue reading The future of Siri, or: why private inference isn't private enough -> ## Encrypted reasoning fields in LLM APIs: a hobby project exploring signed thinking blocks DevFeed: [Encrypted reasoning fields in LLM APIs: a hobby project exploring signed thinking blocks]() Original publisher: [Read original article]() Author: Matthew Green Published: 2026-05-29T03:52:19Z Content type: opinion Language: en Sources: [Matthew Green]() Topics: [Large Language Model](), [API](), [Prompt Engineering](), [Claude](), [OpenClaw](), [Security](), [OpenAI]() Tags: [agent](), [agents](), [ai](), [api](), [attacks](), [chain-of-thought](), [claude](), [coding-agents](), [cryptography](), [frontier-llm-apis](), [llms](), [openai](), [openclaw](), [prompt](), [security]() ### AI overview This opinion article describes a hobby project investigating encrypted or signed reasoning fields exposed by LLM APIs. It discusses configuring an OpenClaw agent to use Claude, comparing Claude's Messages API with OpenAI's Responses API, and examining hidden chain-of-thought data. An August 11, 2026 update says European researchers developed a working attack inspired by the post. ### Source excerpt Update August 11, 2026: A group of researchers from all over Europe were inspired by this post, and actually turned it into a real working attack! Check out their writeup and paper here. This is a quick post I wanted to write about a hobby project I spent a weekend on. It has little to ... Continue reading Let's talk about encrypted reasoning -> ## Anonymous credentials: an illustrated primer (Part 2) DevFeed: [Anonymous credentials: an illustrated primer (Part 2)]() Original publisher: [Read original article]() Author: Matthew Green Published: 2026-04-17T17:19:15Z Content type: tutorial Language: en Sources: [Matthew Green]() Topics: [Cryptography](), [Security, Privacy and Abuse Prevention]() Tags: [ai](), [anonymous-credentials](), [artificial-intelligence](), [attacks](), [credentials](), [cybersecurity](), [privacy](), [resources](), [security](), [state](), [technology]() ### AI overview Part two of an illustrated primer on anonymous credentials moves from the theoretical overview in part one toward practical discussion of real-world credential systems. It explains privacy-preserving authentication, credential showing without linkability, limits on credential reuse, cloning attacks, and expressive claims. ### Source excerpt This is the second in a series of posts about anonymous credentials. You can find the first part here. In the previous post, we introduced the notion of anonymous credentials as a technique that allows users to authenticate to a website without sacrificing their privacy. As a quick reminder, an anonymous credential system consists of ... Continue reading Anonymous credentials: an illustrated primer (Part 2) -> ## Anonymous credentials: an illustrated primer DevFeed: [Anonymous credentials: an illustrated primer]() Original publisher: [Read original article]() Author: Matthew Green Published: 2026-03-02T17:29:36Z Content type: tutorial Language: en Sources: [Matthew Green]() Topics: [Authentication](), [Cryptography](), [Security & Privacy]() Tags: [ai](), [anonymous-credentials](), [artificial-intelligence](), [authentication](), [cryptography](), [cybersecurity](), [mfa](), [passwords](), [privacy](), [security](), [technology]() ### AI overview This primer introduces anonymous authentication as a computer-security problem and explains how websites use credentials, pseudonymous accounts, cookies, CAPTCHAs, MFA, and passkeys to control access. It argues that advertising-driven data collection and expanding age-verification laws are pushing more services toward identity checks, potentially reducing anonymous online use. ### Source excerpt This post has been on my back burner for well over a year. This has bothered me, since with every month that goes by, I become more convinced that anonymous authentication the most important topic we could be talking about as cryptographers. This isn't just because I love neat cryptography: it's that I don't trust ... Continue reading Anonymous credentials: an illustrated primer -> ## WhatsApp Encryption, a Lawsuit, and a Lot of Noise DevFeed: [WhatsApp Encryption, a Lawsuit, and a Lot of Noise]() Original publisher: [Read original article]() Author: Matthew Green Published: 2026-02-02T18:25:32Z Content type: opinion Language: en Sources: [Matthew Green]() Topics: [Encryption](), [End-to-End Encryption](), [Messaging](), [Meta](), [Protocol (disambiguation)](), [Internet]() Tags: [ai](), [digital-marketing](), [encryption](), [lawsuit](), [messaging](), [meta](), [news](), [protocol](), [security](), [signal](), [technology](), [whatsapp]() ### AI overview This explainer examines allegations in a class action lawsuit that WhatsApp can read users' messages despite advertising end-to-end encryption through the Signal protocol. It notes that the complaint provides little solid evidence, while the allegations have been amplified online and reportedly prompted a US investigation into Meta. ### Source excerpt It's not every day that we see mainstream media get excited about encryption apps! For that reason, the past several days have been fascinating, since we've been given not one but several unusual stories about the encryption used in WhatsApp. Or more accurately, if you read the story, a pretty wild allegation that the widely-used ... Continue reading WhatsApp Encryption, a Lawsuit, and a Lot of Noise -> ## Kerberoasting DevFeed: [Kerberoasting]() Original publisher: [Read original article]() Author: Matthew Green Published: 2025-09-10T12:00:00Z Content type: opinion Language: en Sources: [Matthew Green]() Topics: [Vulnerabilities](), [active directory](), [Authentication](), [Windows](), [ransomware](), [Cybercrime]() Tags: [active-directory](), [attacks](), [authentication](), [computer](), [microsoft](), [passwords](), [ransomware](), [vulnerabilities](), [windows]() ### AI overview This article explains Kerberoasting, a long-standing attack against environments using Microsoft Active Directory. It describes how the technique relates to service accounts, centralized authentication, and RC4, and connects it to the May 2024 ransomware attack on Ascension Health based on a letter from Senator Wyden to Microsoft. ### Source excerpt I learn about cryptographic vulnerabilities all the time, and they generally fill me with some combination of jealousy ("oh, why didn't I think of that") or else they impress me with the brilliance of their inventors. But there's also another class of vulnerabilities: these are the ones that can't possibly exist in important production software, ... Continue reading Kerberoasting -> ## A bit more on Twitter/X's new encrypted messaging DevFeed: [A bit more on Twitter/X's new encrypted messaging]() Original publisher: [Read original article]() Author: Matthew Green Published: 2025-06-09T18:22:31Z Content type: article Language: en Sources: [Matthew Green]() Topics: [End-to-End Encryption](), [X (Twitter)](), [Encryption](), [Security](), [vulnerability](), [public key](), [Ratchet](), [Server](), [passwords](), [Meta]() Tags: [e2e](), [encryption](), [instagram](), [messaging](), [messenger](), [protocol](), [protocols](), [public-key](), [secret-storage](), [security](), [signal](), [technology](), [vulnerability]() ### AI overview This article examines XChat, X's end-to-end encrypted messaging protocol, focusing on its lack of forward secrecy and its server-side storage of user private keys. It explains the Juicebox key-storage design and argues that the security of the system depends heavily on its deployment and server protections. ### Source excerpt Update 6/10: Based on a short conversation with an engineering lead at X, some of the devices used at X are claimed to be using HSMs. See more further below. Matthew Garrett has a nice post about Twitter (uh, X)'s new end-to-end encryption messaging protocol, which is now called XChat. The TL;DR of Matthew's post ... Continue reading A bit more on Twitter/X's new encrypted messaging -> ## The case for adding disappearing messages to Apple iMessage DevFeed: [The case for adding disappearing messages to Apple iMessage]() Original publisher: [Read original article]() Author: Matthew Green Published: 2025-03-01T16:53:30Z Content type: opinion Language: en Sources: [Matthew Green]() Topics: [Cryptography](), [Encryption](), [Messaging](), [Post-Quantum](), [iphone]() Tags: [apple](), [cryptography](), [cybersecurity](), [encryption](), [iphone](), [messaging](), [post-quantum](), [security]() ### AI overview This opinion piece examines whether Apple iMessage is secure despite its end-to-end encryption and post-quantum security. It argues that message persistence creates privacy risks and makes the case for adding disappearing messages. ### Source excerpt This is a cryptography blog and I always feel the need to apologize for any post that isn't "straight cryptography." I'm actually getting a little tired of apologizing for it (though if you want some hard-core cryptography content, there's plenty here and here.) Sometimes I have to remind my colleagues that out in the real ... Continue reading Dear Apple: add "Disappearing Messages" to iMessage right now ->