These are some challenges I made for CTF competitions organized by hxp.
The numbers are a very rough difficulty estimate on a scale from 0 to 9.
## hxp CTF 2017

### cryptography

- (9)
**categorical**: find collisions for the CGL supersingular isogeny hash function. files writeup
- (7)
**notsosmart**: crack RSA keys generated using a bad key generation algorithm. files solution
- (6)
**4ES**: break 4-round AES. files solution
- (3)
**flea**: crack an RSA key given some leakage depending on the factors. files solution
- (2)
**ouchenticated**: break a homebrew CRC-based message authentication code. files solution

## TUMCTF 2016

### cryptography

### exploitation

- (6)
**c_with_templates**: embed printable shellcode into a constant string at compile time. files

### reversing

- (5)
**lambda0xe**: reverse-engineer obfuscated C++14 code. files

## TUMCTF Teaser 2015

### cryptography

- (6)
**linear**: linear cryptanalysis of a toy block cipher. files
- (2)
**really_slow_arithmetic**: optimize an RSA private key. writeup