nextco's Crackme 4 by @rextco



8:41 PM 02/16/2019




Target: Get the flag I enjoy a lot with crackmes in which I learned new things. hopefully this crack will fulfill that purpose

GautamGreat on 9:26 AM 02/20/2019: After little math I got a password it shows a message box but it seems encrypted. one of the password is : 0148726828

nextco on 10:11 PM 03/18/2019: Hints: Look the logo. 0, 1, 2, 3, ...,7

AshVsEvilDead on 6:25 PM 04/08/2019: There is a complex relationship between the name and the key. (1st) the key is in the form XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. The "-"s are discarded and its passed through a 'hashing' algorithm of some sort to produce 16 characters of the hashed key. (2) The name is 'topped up' to 16 characters by looping through the characters from zero. The trailing zero is included in the characters. (3)The key hash is appended to the topped up name and the first 30 characters are passed through another hashing algorithm. The result of this is a 2 letter code that is compared to the last 2 digits of the hashed key. They should be equal. One can see that the relation ship between the name and the key is complex. I wonder what algo u are using?

nextco on 10:12 AM 04/09/2019: @AshVsEvilDead, i think you comment is for another crackme, because the format on this crackme is different. Only numbers ( blocked by gui)

Xor0 on 7:34 PM 05/02/2019: Another nice one from @nextco. I found the fl4g ;-) I don't know if i will post a full solution. I just brute forced this, but the flag message suggests maybe there is a better way. Certainly we could have just did some simple xor key brute forcing on the MessageBox string. See cryptopals set 1 challenge 6.