zh3r0 2020 Crypto - Uncipher Me
Uncipher Me
Description
Challenge Files
ct.txt
key.txt
key_2.txt
key_3.txt
Lets begin with the keys.
cat key.txt
TjogR0kzRE9OWldHUVpER01SVkdFWURLT0JWSEUyRE1NSllHNFpEQU5CVEdBNFRJTUJSR0VZVEdNQlpHTTRUU01CWUdJMlRNTUJRR1U0RElOSlhHUTJUS05CUUdBM1RLTlpTRzQzRE1PQlRIRTJESU9KWUc0M0RRTVpXSEU0VE1NWlpHUVlUU01CVEhFWkRBTkpYSEU0RE1NSldHTVlURU5KU0c0N...
zh3r0 2020 Crypto - RSA warmup
RSA-Warmup
Description
RSA is one of the first public-key cryptosystems and is widely used for secure data transmission. In such a cryptosystem, the encryption key is public and distinct from the decryption key which is kept secret.
You all know this :p
here is a warmup question.
nc crypto.zh3r0.ml 8451
Author : Finch
Lets quickly net cat
n...
zh3r0 2020 Crypto - Mix
Mix
Description
At the BASEment no. 65536, A man is irritated with SHIFT key in his KEYBOARD as it's a sticky key, A kid is having chocolate icecream with a SPOON.
Author : Whit3_D3vi1
Challenge Files
Mix.zip
Mix/chall_encrypted.txt
Mix/flag.txt
flag.txt reads
If you opened this then you are a n00b
HAHA VERY FU...
zh3r0 2020 Crypto - Hastads Message
Hastad’s message
Description
My friend Hastad send me a message but I am not able to read it. Only thing I know is its different each time.
nc crypto.zh3r0.ml 7419
Author : Finch
Lets see what happens on netcatting the server
nc crypto.zh3r0.ml 7419
N: 239609496311365490105807093714474593207717229906416564692897157101422954951249486211586878...
zh3r0 2020 Crypto - Double Fish
Double Fish
Description
There two fishes in the Xander's Operative Register
A flag is waiting for you when you catch both.
_0m\K2!2%\ggrdups\vd~gq
Author : Finch
Challenge Files
chall.txt
cat chall.txt
xxkxxxxkxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxcddddddddddddddddddddddddddddddddddddddddddcxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx...
zh3r0 2020 Crypto - Analyze Me
Analyse Me
Description
i have a server's ip which gives us the flag,
but i'm not so good in cracking it. Can you decode the flag for me?
nc crypto.zh3r0.ml 3871
Author : Whit3_D3vi1
Challenge files
server.py earlier analyse.py which is quite unsolvable according to me
Lets take a look at contents of server.py
from Crypto.Util.number im...
Nahamcon 2020 Crypto - elsa4
Elsa4
Apparently, its an instance of LC4 cipher.
We are provided with a subtle hint Frozen in time which could mean random is seeded with the present time, confirmed by the fact that time is provided at the start of the challenge.
Now, all we need to figure out is the length of nonce, however it is implemented.
I also wrote encrypt, decrypt...
Nahamcon 2020 Crypto - Unvreakable Vase
Unvreakable Vase
We are provided with prompt.txt, which reads
zmxhz3tkb2vzx3roaxnfzxzlbl9jb3vudf9hc19jcnlwdg9vb30=
This seems to be base64 encoded but I think all the letters are converted to lowercase as hinted by squished and flat
import base64
data = 'zmxhz3tkb2vzx3roaxnfzxzlbl9jb3vudf9hc19jcnlwdg9vb30='
m1 = base64.b64decode(data)
print...
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