Matthew Green

Matthew Green

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Matthew Green is a cryptography expert and Johns Hopkins professor known for his work on applied cryptography, secure storage, and privacy-enhancing technologies.

Ghost Participants Won’t Crack Encrypted Group Chats
SocialMay 9, 2026

Ghost Participants Won’t Crack Encrypted Group Chats

“Ghost participants” have been floating around for years as a way to break encrypted messaging. The idea is to add invisible extra people (the police, essentially) to group chats. It’s a dumb idea, and let me explain why.

By Matthew Green
OpenRouter and Cheap Chinese Models Outpace AI Giants
SocialMay 6, 2026

OpenRouter and Cheap Chinese Models Outpace AI Giants

Everyone is betting on whether Claude or OpenAI or Grok “wins” the AI race. I’m betting on OpenRouter, with people running dirt-cheap Chinese models.

By Matthew Green
Today's Freeze Controls Won’t Guarantee Future Stability
SocialMay 6, 2026

Today's Freeze Controls Won’t Guarantee Future Stability

“Stablecoins have a freeze function” is like “Google isn’t evil.” Sure, that’s what they have today. It’s not what they’ll have in 2033.

By Matthew Green
World Rushes to Enforce ID, Threatening VPN Anonymity
SocialMay 5, 2026

World Rushes to Enforce ID, Threatening VPN Anonymity

There’s something ominous about the speed with which the entire world has marched to require identification on platforms and, as I expected, begin the process of banning anonymous VPNs.

By Matthew Green
Public Hype on Quantum Computing Eases Cryptography Concerns
SocialApr 30, 2026

Public Hype on Quantum Computing Eases Cryptography Concerns

The fact that major public companies are hyping quantum computer progress actually makes QC progress less scary for cryptography.

By Matthew Green
US Drops Probe Into WhatsApp‑Meta Chat Visibility Claims
SocialApr 28, 2026

US Drops Probe Into WhatsApp‑Meta Chat Visibility Claims

The US has abruptly ended its investigation into claims that WhatsApp chats were visible to Meta. https://t.co/f1WXpQz58J

By Matthew Green
Bet: Quantum Won’t Break ECC by 2032, ML‑KEM
SocialApr 7, 2026

Bet: Quantum Won’t Break ECC by 2032, ML‑KEM

I’m making a bet with Filippo Valsorda that quantum computers won’t break ECC by 2029/2032, and (secondarily) that one version of ML-KEM will be de-standardized. I have loads of confidence in the former and little in the latter. I just...

By Matthew Green
Iran Seeks Stablecoin Payments for Hormuz Transits
SocialApr 6, 2026

Iran Seeks Stablecoin Payments for Hormuz Transits

I’ve seen reports that Iran is demanding payment in stablecoins for Hormuz transits. Does anyone know the addresses or chain details?

By Matthew Green
Blockchain Still Alive: New Attack and Iran Toll Adoption
SocialApr 5, 2026

Blockchain Still Alive: New Attack and Iran Toll Adoption

All semester I’ve been depressingly short on interesting news for my blockchains class, and I’ve been wondering if this field was moribund. This attack, along with the news that Iran is accepting Hormuz tolls in blockchain-based currencies, gives us something...

By Matthew Green
State Quantum Power Lies in Hidden Communications Exploitation
SocialMar 31, 2026

State Quantum Power Lies in Hidden Communications Exploitation

Ok I just want to add one thing. Folks, for state actors, the value of having a quantum computer is massively higher if you DON’T tell people you have a quantum computer. Exploiting Bitcoin is a parlor trick. Exploiting the world’s communications...

By Matthew Green
Quantum Crypto Threats Unlikely Within Our Lifetime
SocialMar 31, 2026

Quantum Crypto Threats Unlikely Within Our Lifetime

Neat paper on securing cryptocurrencies against quantum attacks. I want to stress that I am not convinced we have anything to worry about in my lifetime. This tweet might haunt me. https://t.co/d1i4reP93g

By Matthew Green
Generative AI Poised to Monetize Private Data Troves
SocialMar 22, 2026

Generative AI Poised to Monetize Private Data Troves

I want to continue a bit on this subject, which (so far) I see very little concern about. There are vast stores of private data that we’ve built up in various places, including messaging apps. A real “killer app” for...

By Matthew Green
Moxie‑Meta AI Partnership Raises Privacy Fears
SocialMar 21, 2026

Moxie‑Meta AI Partnership Raises Privacy Fears

People keep asking me about Moxie’s partnership with Meta. They seem enthusiastic about the prospect of TEE-based AI inference integrated with confidential messengers. I guess I’m in the minority here, because this scares the pants off of me.

By Matthew Green
Meta Removes Instagram Encryption, Sparking User Frustration
SocialMar 21, 2026

Meta Removes Instagram Encryption, Sparking User Frustration

Here’s a good article about Meta’s very frustrating decision to pull encryption out of Instagram. https://t.co/ajH18YCDZK

By Matthew Green