Categories
Cryptography

Learning from LadderLeak: Is ECDSA Broken?

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 […]

Categories
Cryptography

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 […]

Categories
Cryptography

Hedged Signatures with Libsodium using Dhole

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 […]

Categories
Cryptography

A Furry’s Guide to Digital Signature Algorithms

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 […]