An anonymous reader shares a report: After last week's major AWS outage took Signal along with it, Elon Musk was quick to criticize the encrypted messaging app's reliance on big tech. But Signal president Meredith Whittaker argues that the company didn't have any other choice but to use AWS or another major cloud provider. "The problem here is not that Signal 'chose' to run on AWS," Whittaker writes in a series of posts on Bluesky. "The problem is the concentration of power in the infrastructure space that means there isn't really another choice: the entire stack, practically speaking, is owned by 3-4 players." In the thread, Whittaker says the number of people who didn't realize Signal uses AWS is "concerning," as it indicates they aren't aware of just how concentrated the cloud infrastructure industry is. "The question isn't 'why does Signal use AWS?'" Whittaker writes. "It's to look at the infrastructural requirements of any global, real-time, mass comms platform and ask how it is that we got to a place where there's no realistic alternative to AWS and the other hyperscalers."

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"Eleven days ago, the nonprofit entity that develops the protocol, Signal Messenger LLC, published a 5,900-word write-up describing its latest updates that bring Signal a significant step toward being fully quantum-resistant," writes Ars Technica: The mechanism that has made this constant key evolution possible over the past decade is what protocol developers call a "double ratchet." Just as a traditional ratchet allows a gear to rotate in one direction but not in the other, the Signal ratchets allow messaging parties to create new keys based on a combination of preceding and newly agreed-upon secrets. The ratchets work in a single direction, the sending and receiving of future messages. Even if an adversary compromises a newly created secret, messages encrypted using older secrets can't be decrypted... [Signal developers describe a "ping-pong" behavior as parties take turns replacing ratchet key pairs one at a time.] Even though the ping-ponging keys are vulnerable to future quantum attacks, they are broadly believed to be secure against today's attacks from classical computers. The Signal Protocol developers didn't want to remove them or the battle-tested code that produces them. That led to their decision to add quantum resistance by adding a third ratchet. This one uses a quantum-safe Key-Encapsulation Mechanism (KEM) to produce new secrets much like the Diffie-Hellman ratchet did before, ensuring quantum-safe, post-compromise security... The technical challenges were anything but easy. Elliptic curve keys generated in the X25519 implementation are about 32 bytes long, small enough to be added to each message without creating a burden on already constrained bandwidths or computing resources. A ML-KEM 768 key, by contrast, is 1,000 bytes. Additionally, Signal's design requires sending both an encryption key and a ciphertext, making the total size 2,272 bytes... To manage the asynchrony challenges, the developers turned to "erasure codes," a method of breaking up larger data into smaller pieces such that the original can be reconstructed using any sufficiently sized subset of chunks... The Signal engineers have given this third ratchet the formal name: Sparse Post Quantum Ratchet, or SPQR for short. The third ratchet was designed in collaboration with PQShield, AIST, and New York University. The developers presented the erasure-code-based chunking and the high-level Triple Ratchet design at the Eurocrypt 2025 conference. Outside researchers are applauding the work. "If the normal encrypted messages we use are cats, then post-quantum ciphertexts are elephants," Matt Green, a cryptography expert at Johns Hopkins University, wrote in an interview. "So the problem here is to sneak an elephant through a tunnel designed for cats. And that's an amazing engineering achievement. But it also makes me wish we didn't have to deal with elephants." Thanks to long-time Slashdot reader mspohr for sharing the article.

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Cryptologist/CS professor Daniel J. Bernstein is alleging that America's National Security Agency is attempting to influence NIST post-quantum cryptography standards. Bernstein first emphasizes that it's normal for post-quantum cryptography (or "PQ") to be part of "hybrid" security that also includes traditional pre-quantum cryptography. (Bernstein says this is important because since 2016, "We've seen many breaks of post-quantum proposals...") "The problem in a nutshell. Surveillance agency NSA and its [UK counterpart] GCHQ are trying to have standards-development organizations endorse weakening [pre-quantum] ECC+PQ down to just PQ." Part of this is that NSA and GCHQ have been endlessly repeating arguments that this weakening is a good thing... I'm instead looking at how easy it is for NSA to simply spend money to corrupt the standardization process.... The massive U.S. military budget now publicly requires cryptographic "components" to have NSA approval... In June 2024, NSA's William Layton wrote that "we do not anticipate supporting hybrid in national security systems"... [Later a Cisco employee wrote of selling non-hybrid cryptography to a significant customer, "that's what they're willing to buy. Hence, Cisco will implement it".] What do you do with your control over the U.S. military budget? That's another opportunity to "shape the worldwide commercial cryptography marketplace". You can tell people that you won't authorize purchasing double encryption. You can even follow through on having the military publicly purchase single encryption. Meanwhile you quietly spend a negligible amount of money on an independent encryption layer to protect the data that you care about, so you're actually using double encryption. This seems to be a speculative scenario. But Bernstein is also concerned about how the Internet Engineering Task Force handled two drafts specifying post-quantum encryption mechanisms for TLS ("the security layer inside HTTPS and inside various other protocols"). For a draft suggesting "non-hybrid" encryption, there were 20 statements of support (plus 2 more only conditionally supporting it), but 7 more statements unequivocally opposing adoption, including one from Bernstein. The IETF has at times said they aim for "rough consensus" — or for "broad consensus" — but Bernstein insists 7 opposers in a field of 29 (24.13%) can't be said to match the legal definition of consensus (which is "general agreement"). "I've filed a formal complaint regarding the claim of consensus to adopt." He's also written a second blog post analyzing the IETF's decision-making process in detail. "It's already bad that the IETF TLS working group adopted non-hybrid post-quantum encryption without official answers to the objections that were raised. It's much worse if the objections can't be raised in the first place." Thanks to alanw (Slashdot reader #1,822) for spotting the blog posts.

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BrianFagioli shares a report from NERDS.xyz: Signal has introduced the Sparse Post Quantum Ratchet (SPQR), a new upgrade to its encryption protocol that mixes quantum safe cryptography into its existing Double Ratchet. The result, which Signal calls the Triple Ratchet, makes it much harder for even future quantum computers to break private chats. The change happens silently in the background, meaning users do not need to do anything, but once fully rolled out it will make harvested messages useless even to adversaries with quantum power. The company worked with researchers and used formal verification tools to prove the new protocol's security. Signal says the upgrade preserves its guarantees of forward secrecy and post compromise security while adding protection against harvest now, decrypt later attacks. The move raises a bigger question: will this be enough when large scale quantum computers arrive, or will secure messaging need to evolve yet again?

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The UK government has issued a new order to Apple to create a backdoor into its cloud storage service, this time targeting only British users' data, despite US claims that Britain had abandoned all attempts to break the tech giant's encryption. Financial Times: The UK Home Office demanded in early September that Apple create a means to allow officials access to encrypted cloud backups, but stipulated that the order applied only to British citizens' data, according to people briefed on the matter. A previous technical capability notice (TCN) issued in January sought global access to encrypted user data. That move sparked a diplomatic clash between the UK and US governments and threatened to derail the two nations' efforts to secure a trade agreement. In February, Apple withdrew its most secure cloud storage service, iCloud Advanced Data Protection, from the UK. "Apple is still unable to offer Advanced Data Protection in the United Kingdom to new users," Apple said on Wednesday. "We are gravely disappointed that the protections provided by ADP are not available to our customers in the UK given the continuing rise of data breaches and other threats to customer privacy." It added: "As we have said many times before, we have never built a back door or master key to any of our products or services and we never will."

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The Swiss government could soon require service providers with more than 5,000 users to collect government-issued identification, retain subscriber data for six months and, in many cases, disable encryption. From a report: The proposal, which is not subject to parliamentary approval, has alarmed privacy and digital-freedoms advocates worldwide because of how it will destroy anonymity online, including for people located outside of Switzerland. A large number of virtual private network (VPN) companies and other privacy-preserving firms are headquartered in the country because it has historically had liberal digital privacy laws alongside its famously discreet banking ecosystem. Proton, which offers secure and end-to-end encrypted email along with an ultra-private VPN and cloud storage, announced on July 23 that it is moving most of its physical infrastructure out of Switzerland due to the proposed law. The company is investing more than $117 million in the European Union, the announcement said, and plans to help develop a "sovereign EuroStack for the future of our home continent." Switzerland is not a member of the EU. Proton said the decision was prompted by the Swiss government's attempt to "introduce mass surveillance."

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