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Cryptography - HTB

This is all retried crypto challenge from hackthebox.

hashtag
Weak RSA

chevron-rightChallenge Descriptionhashtag

Can you decrypt the message and get the flag?

This challenge gave us two file which is flag.enc and key.pub 

└──╼ [??]$ cat flag.enc 
_vc[~kZ1Ĩ4I9V^G(+3Lu"$F0VP־j@|j{¾,YEXx,cN&Hl2Ӎ


 $ cat key.pub 
-----BEGIN PUBLIC KEY-----
MIIBHzANBgkqhkiG9w0BAQEFAAOCAQwAMIIBBwKBgQMwO3kPsUnaNAbUlaubn7ip
4pNEXjvUOxjvLwUhtybr6Ng4undLtSQPCPf7ygoUKh1KYeqXMpTmhKjRos3xioTy
23CZuOl3WIsLiRKSVYyqBc9d8rxjNMXuUIOiNO38ealcR4p44zfHI66INPuKmTG3
RQP/6p5hv1PYcWmErEeDewKBgGEXxgRIsTlFGrW2C2JXoSvakMCWD60eAH0W2PpD
qlqqOFD8JA5UFK0roQkOjhLWSVu8c6DLpWJQQlXHPqP702qIg/gx2o0bm4EzrCEJ
4gYo6Ax+U7q6TOWhQpiBHnC0ojE8kUoqMhfALpUaruTJ6zmj8IA1e1M6bMqVF8sr
lb/N
-----END PUBLIC KEY-----

You can learn RSA from herearrow-up-right. For beginner , we can use RsaCTFtoolarrow-up-right from github to solve this.

HTB{s1mpl3_Wi3n3rs_4tt4ck}

hashtag
Classic, yet complicated!

chevron-rightChallenge Descriptionhashtag

Find the plaintext, the key is your flag!

Flag format : HTB{key in lowercase}``

ciphertext.txt

alp gwcsepul gtavaf, nlv prgpbpsu mb h jcpbyvdlq, ipltga rv glniypfa we ekl 16xs nsjhlcb. px td o lccjdstslpahzn fptspf xstlxzi te iosj ezv sc xcns ttsoic lzlvrmhaw ez sjqijsa xsp rwhr. tq vxspf sciov, alp wsphvcv pr ess rwxpqlvp nwlvvc dyi dswbhvo ef htqtafvyw hqzfbpg, ezutewwm zcep xzmyr o scio ry tscoos rd woi pyqnmgelvr vpm . qbctnl xsp akbflowllmspwt nlwlpcg, lccjdstslpahzn fptspfo oip qvx dfgysgelipp ec bfvbxlrnj ojocjvpw, ld akfv ekhr zys hskehy my eva dclluxpih yoe mh yiacsoseehk fj l gebxwh sieesn we ekl iynfudktru. xsp yam zd woi qwoc.

First I though this is rot13 but it's not, but as a description we need key to decrypt it. So it can be Vigenere Ciphier . I used this sitearrow-up-right to automatic decrypt it .

Now we got the readable text with the key HELLOWORLD . As a description, the flag is key in lowercase.

HTB{helloworld}

hashtag
Brainy's Cipher

chevron-rightChallenge Descriptionhashtag

Brainy likes playing around with esoteric programming. He also likes math and has therefore encrypted his very secure password with a popular encryption algorithm. Claiming that his password cannot be retrieved now, he has sent the ciphertext to some of his friends. Can you prove to Brainy that his password can actually be recovered?

We got a text file which is brainy.txt and when you look up inside of that file,

I know this is brainfuck cipher and we can use decode.frarrow-up-right but in this case I used thisarrow-up-right site to get better result.

We will get another encrypted text and I noticed that there is p,q, dp, dq etc.. .So this must be RSA Encryption and I create a python script to solve this.

HTB{ch1n3z_r3m4ind3r_the0rem_r0ck$$$_9792}

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