Elliptic curves
Posts with this tag
Posts
-
Elliptic Curves from Scratch: Group Law, Double-and-Add and a Toy ECDH
Building elliptic-curve cryptography up from the chord-and-tangent rule to scalar multiplication and a working Diffie–Hellman exchange on a 103-point curve, then showing exactly why that curve is worthless.
-
CO: A Cubic Surface, a Hyperplane Section, and a Flag Collected One Small Prime at a Time
A write-up of the crypto challenge CO from WannaGame Championship 2025, where the group lives on a cubic surface in projective 3-space, a hyperplane through the given points cuts it into an ordinary elliptic curve, and the same secret scalar reused across attacker-chosen primes falls to Pohlig-Hellman and the CRT.
