HSCTF 2020 Crypto - Morbid
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HSCTF 2020 Crypto - Extremely Complex Challenge
Extremely Complex Challenge
We are given two points on an Elliptic Curve, its order and parameter b.
Using these quantities, we can recover parameter a.
y^2 = x^3 + ax + b (mod p)
y^2 - x^3 - b = ax (mod p)
If we have two points on curve, (x1, y1) and (x2, y2), we can get
(y1^2 - x1^3) - (y2^2 - x2^3) = a(x1 - x2) (mod p)
a = (x1 - x2)^-1...
HSCTF 2020 Crypto - Chonky E
Chonky E
Allen and Jason rely on two different cryptosystems to keep their information secure.
Allen uses the RSA cryptosystem, given by the following public key:
e = 9104311840982855079677374551858598115118020610100513511756586560297872287847849444704878355757181398052564372532337748824983886089778468392702990618894700114963210151336725826732...
HSCTF 2020 Crypto - Affina and the quadratics
Affina and the Quadratics
We are given this image, and hinted towards the name Affina.
With a description reading
Affina was struggling with her graphing quadratics homework. Bored, she decided to cheat by using Desmos to graph the given quadratic, and then realized that she could use it to send messages to her best friend without anyone no...
60 post articles, 8 pages.