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Halloween Party - ASIS CTF Quals 2019

s0rc3r3r
2019-04-23
Crypto / Elliptic-Curves

tl;dr

  1. Find Elliptic Curve parameters from given points on the curve
  2. Find x-coordinate of 2*P, given y-coordinate of 2*P
  3. Invert 2 over mod (P.order()) and multiply the result with 2*P to get P
  4. Submit ASIS{P.x} as the flag
Read More

Alice sent Bob a meme - UTCTF 2019

s0rc3r3r
2019-03-12
Crypto / Elliptic-Curves

tl;dr

  1. Extract data from given images using binwalk
  2. Tranform given diophantine equation into a cubic curve and retrieve EC parameters
  3. Solve ECDLP given in extracted data using Pohlig Hellman Algorithm
Read More
ECDLP PohligHellman

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