find_the_password by oxygen240

Simply put, the algorithm calculates a hash value using a manually created hash function and checks it against a hard-coded value. It is impossible to recover the original key (if the author had one), so I chose the simplest solution – brute force, given that the algorithm is trivial and will cause many collisions.

These are the all (printable) options for key_length = 4:

FOUND: ':S&7'
FOUND: '`\@7'
FOUND: ':Rf7'
FOUND: ':S%w'
FOUND: '`\?w'
FOUND: ':Rew'

FOUND: ':S&7'

FOUND: '`\@7'

FOUND: ':Rf7'

FOUND: ':S%w'

FOUND: '`\?w'

FOUND: ':Rew'

And some examples for key_length = 5:

FOUND: 'CQ: 7'
FOUND: '|_A 7'
FOUND: '0LM 7'
FOUND: 'iZT 7'
FOUND: 'VUg 7'
FOUND: 'CPz 7'
FOUND: 'FP)"7'
FOUND: '3K<"7'
FOUND: 'lYC"7'
FOUND: ' FO"7'
FOUND: 'YTV"7'

FOUND: 'CQ: 7'

FOUND: '|_A 7'

FOUND: '0LM 7'

FOUND: 'iZT 7'

FOUND: 'VUg 7'

FOUND: 'CPz 7'

FOUND: 'FP)"7'

FOUND: '3K<"7'

FOUND: 'lYC"7'

FOUND: ' FO"7'

FOUND: 'YTV"7'

I solved this problem by writing a simple brute-force algorithm that can be found here.

Get the crackme here.