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Elliptic Curve Digital Signature Algorithm (ECDSA) Defined
The elliptic curve digital signature algorithm (ECDSA) is a form of digital signature. Cryptocurrency traders use it almost exclusively to prove their identities. But some websites use the technology too.
We cover what makes the ECDSA algorithm different and uncover pitfalls that might make it risky for websites to implement.
How does a signature algorithm work?
Let's begin with a bit of background on signature algorithms and the protections they offer.
When you visit a site that begins with https://, your browser does two important things:
- Connect: The two systems use an encrypted channel to exchange information.
- Verify: The browser uses cryptography to ensure that the site isn’t a fake put up by a bad actor.
Signature algorithms make this process possible. Both browsers and servers have two keys (public and private) made up of mathematically related numbers. A private key creates a digital signature, and a public key can check its validity.
Since the mid-1990s, websites have used relatively simple mathematical principles in key generation. Hackers love this idea, as cracking the code is somewhat easy.
What is ECDSA?
Complexity sits at the core of the ECDSA key-creation process.
It’s mathematically simple to compute a key in one direction with ECDSA, but it’s very difficult to reverse the process. We won’t dig too deep into the math, but know that it begins with a curve represented by (y2 = x3 + ax + b). A number on that curve is multiplied by another, and that produces yet another point on the curve. Even if you know one number, finding the other is challenging.
Breaking the ECDSA curve means solving something called the elliptic curve discrete logarithm problem, and that’s notoriously hard to do. Hackers keep trying, but it’s a very tough math challenge to overcome.
ANSI accepted ECDSA as a standard in 1999, and IEEE and NIST accepted it as a standard in 2000. Some sites have implemented this form of…