Crackpot cryptography, overconfidence, and attempts to defraud governments and private-sector startups.
Previously on Dead Ends in Cryptanalysis, we talked about length-extension attacks and precisely why modern hash functions like SHA-3 and BLAKE2 aren’t susceptible. The art and science of side-channel cryptanalysis is one of the subjects I’m deeply fascinated by, and it’s something you’ll hear me yap about a lot on this blog in the future. […]
How and why XSalsa20/XChaCha were designed, and why they’re secure.
Cryptographers and cryptography engineers love to talk about the latest attacks and how to mitigate them. LadderLeak breaks ECDSA with less than 1 bit of nonce leakage? Raccoon attack brings the Hidden Number attack to finite field Diffie-Hellman in TLS? And while this sort of research is important and fun, most software developers have much […]
Governments are back on their anti-encryption bullshit again. Between the U.S. Senate’s “EARN IT” Act, the E.U.’s slew of anti-encryption proposals, and Australia’s new anti-encryption law, it’s become clear that the authoritarians in office view online privacy as a threat to their existence. Normally, when the governments increase their anti-privacy sabre-rattling, technologists start talking more […]
Solving For “Why?”
Why blog about cryptography as a furry?
This is the first entry in a (potentially infinite) series of dead end roads in the field of cryptanalysis. Cryptography engineering is one of many specialties within the wider field of security engineering. Security engineering is a discipline that chiefly concerns itself with studying how systems fail in order to build better systems–ones that are […]
A paper was published on the IACR’s ePrint archive yesterday, titled LadderLeak: Breaking ECDSA With Less Than One Bit of Nonce Leakage. The ensuing discussion on /r/crypto led to several interesting questions that I thought would be worth capturing and answering in detail. What’s Significant About the LadderLeak Paper? This is best summarized by Table […]
Putting the “Fun” in “Hash Function”
There are several different methods for securely hashing a password server-side for storage and future authentication. The most common one (a.k.a. the one that FIPS allows you to use, if compliance matters for you) is called PBKDF2. It stands for Password-Based Key Derivation Function #2. Why #2? It’s got nothing to do with pencils. There […]
In 2017, cryptography researchers from Kudelski Security demonstrated practical fault attacks against EdDSA (specifically Ed25519; RFC 8032). Their techniques are also applicable to Deterministic ECDSA (RFC 6979), and potentially work against any deterministic signature scheme (n.b. the Fiat-Shamir or Schnorr distinction isn’t meaningful in this context). Although that might seem alarming, fault attacks aren’t especially […]
Let’s talk about digital signature algorithms. Digital signature algorithms are one of the coolest ideas to come out of asymmetric (a.k.a. public-key) cryptography, but they’re so simple and straightforward that most cryptography nerds don’t spend a lot of time thinking about them. Even though you are more likely to run into a digital signature as […]