Cryptography FM

On April 19th 2022, Neil Madden disclosed a vulnerability in many popular Java runtimes and development kits. The vulnerability, dubbed "Psychic Signatures", lies in the cryptography for ECDSA signatures and allows an attacker to bypass signature checks entirely for these signatures. How are popular cryptographic protocol implementations in Java affected? What's the state of Java cryptography as a whole? Join Neil, Nadi...

Threema is a Swiss encrypted messaging application. It has more than 10 million users and more than 7000 on-premise customers. Prominent users of Threema include the Swiss Government and the Swiss Army, as well as the current Chancellor of Germany, Olaf Scholz. Threema has been widely advertised as a secure alternative to other messengers.

Kenny, Kien and Matteo from the ETH Zurich Applied Cryptography Group present seven attacks ...

Benjamin Wesolowski talks about his latest paper in which he mathematically proved that the two fundamental problems underlying isogeny-based cryptography are equivalent.

Links and papers discussed in the show:

Music composed by Toby Fox and performed by Sean Schafianski.

Special Guest: Benjamin Wesolowsk...

A team of cryptanalysits presents the first publicly available cryptanalytic attacks on the GEA-1 and GEA-2 algorithms. Instead of providing full 64-bit security, they show that the initial state of GEA-1 can be recovered from as little as 65 bits of known keystream (with at least 24 bits coming from one frame) in time 240 GEA-1 evaluations and using 44.5 GiB of memory. The attack on GEA-1 is based on an exceptional interaction of ...

TLS is an internet standard to secure the communication between servers and clients on the internet, for example that of web servers, FTP servers, and Email servers. This is possible because TLS was designed to be application layer independent, which allows its use in many diverse communication protocols.

ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but u...

Nadim talks with Peter Schwabe and Matthias Kannwischer about the considerations — both in terms of security and performance — when implementing cryptographic primitives for low-level and embedded platforms.

Links and papers discussed in the show:

Music compos...

Wi-Fi is a pretty central technology to our daily lives, whether at home or at the office. Given that so much sensitive data is regularly exchanged between Wi-Fi devices, a number of standards have been developed to ensure the privacy and authentication of Wi-Fi communications.

However, a recent paper shows that every single Wi-Fi network protection standard since 1997, from WEP all the way to WPA3, is exposed to a critical vulner...

Contact discovery is a core feature in popular mobile messaging apps such as WhatsApp, Signal and Telegram that lets users grant access to their address book in order to discover which of their contacts are on that messaging service. While contact discovery is critical for WhatsApp, Signal and Telegram to function properly, privacy concerns arise with the current methods and implementations of this feature, potentially resulting in...

Secure multi-party computation is a fascinating field in cryptography, researching how to allow multiple parties to compute secure operations over inputs while keeping those inputs private. This makes multi-party computation a super relevant technology in areas such as code signing, hospital records and more.

But what does it take to bring secure multi-party computation from the blank slate of academia and into the messiness of th...

On March 1st, 2021, a curious paper appeared on the Cryptology ePrint Archive: senior cryptographer Claus Peter Schnorr submitted research that claims to use lattice mathematics to improve the fast factoring of integers so much that he was able to completely “destroy the RSA cryptosystem” -- certainly a serious claim.

Strangely, while the paper’s ePrint abstract did mention RSA, the paper itself didn’t. Two days later, Schnorr pus...

Zero-Knowledge proofs have broadened the realm of use cases for applied cryptography over the past decade, from privacy-enhanced cryptocurrencies to applications in voting, finance, protecting medical data and more. In 2018, Dr. Eli Ben-Sasson and his team introduced ZK-STARKs, a new zero-knowledge construction that functions without trusted setup, thereby broadening what zero-knowledge systems are capable of. We’ll talk about ZK-S...

Every year, the IACR Real World Cryptography symposium brings together researchers, engineers and practitioners in applied cryptography to discuss cryptography that matters, in the real world. To me, this is the big one! The one cryptography conference that matters the most. Who needs proceedings when you’ve got so much excitement in the air, and so many results and projects that actually have a measurable impact on how cryptograph...

The race for post-quantum cryptographic signature primitives is in its final lap over at NIST, which recently announced DILITHIUM, FALCON and Rainbow as the three signature primitive finalists. But a paper recently published by KU Leuven researcher Ward Beullens claims to find serious weaknesses in the security of Rainbow, one of those three finalists. In fact, the paper claims that the weaknesses are so severe that Rainbow’s secur...

Authenticated encryption such as AES-GCM or ChaCha20-Poly1305 is used in a wide variety of applications, including potentially in settings for which it was not originally designed. A question given relatively little attention is whether an authenticated encryption scheme guarantees “key commitment”: the notion that ciphertext should decrypt to a valid plaintext only under the key that was used to generate the ciphertext.

In realit...

Before there was Signal, before there was WhatsApp, the realm of secure encrypted messaging was ruled by the Off-the-Record secure messaging protocol, created as an alternative to PGP that introduced security properties like forward secrecy and deniability that were considered exotic at the time.

Now, more than a decade later, Off-the-Record messaging, or OTR, has been largely sidelined by Signal variants. But a small team of cryp...

Elliptic-curve signatures have become a highly used cryptographic primitive in secure messaging, TLS as well as in cryptocurrencies due to their high speed benefits over more traditional signature schemes. However, virtually all signature schemes are known to be susceptible to misuse, especially when information about the nonce is leaked to an attacker.

LadderLeak is a new attack that exploits side channels present in ECDSA, claim...

Secure messaging protocols like Signal have succeeded at making end-to-end encryption the norm in messaging more generally. Whether you’re using WhatsApp, Wire, Facebook Messenger’s Secret Chat feature, or Signal itself, you’re benefiting from end-to-end encryption across all of your messages and calls, and it’s so transparent that most users aren’t even aware of it!

One area in which current secure messaging protocols have stalle...

Zero-knowledge proofs have been a notorious research target ever since Zcash and other cryptocurrencies have invented lots of new use cases for them. Range proofs, bullet proofs, you name it – all kinds of zero-knowledge mechanisms have received more and more attention.

But what about using zero-knowledge proofs to prove the existence of a software vulnerability? That way, you can prove that you have a zero-day without risking it ...

The NIST post-quantum competition has started a race for post-quantum cryptography. As a result, we’ve seen a great deal of research into alternative hard mathematical problems to use as a basis for public-key cryptography schemes. Lattice-based cryptography! Error-correcting code based cryptography! And of course, isogeny-based cryptography, have all received enormous renewed interest as a result.

While the NIST post-quantum comp...