# CSAW CTF Qualification Round 2019 : Count On Me

**category** : crypto

**points** : 100

**solves** : 120

## write-up

Find the seed that produce duplicated blocks

Because we have the first 16 characters, we can use the first block to solve the other block by xor

flag: `flag{U_c@n_coUn7_0n_m3_l1kE_123}`

# other write-ups and resources

Original writeup (https://github.com/OAlienO/CTF/tree/master/2019/CSAW-CTF/Count-On-Me).