34 posts tagged with "picoctf"

We are being presented with the following description "Cryptography can be easy, do you know what ROT13 is?" and the following text.

cvpbPGS[arkg_gvzr_V'yy_gel_2_ebhaqf_bs_ebg13_Ncualgvd]

This is a cipher text, meaning that the letters of the alphabet need to be 'moved' 13 places forward, in order to decrypt the message.

Download the python script, pw.txt and flag.txt.en.

cat pw.txt
cat flag.txt.en

python3 ende.py -d flag.txt.en

Enter the password of pw.txt and you get the flag.

First, download all the files provided. They are the following. All of them are needed to live in the same directory in order for this to work.

level5.py
level5.flag.txt.enc
level5.hash.bin
dictionary.txt

Now let's open up the main file which is the level5.py

First, download all the files provided. They are the following. All of them are needed to live in the same directory in order for this to work.

level4.py
level4.flag.txt.enc
level4.hash.bin

Now let's open up the main file which is the level4.py

First, download all the files provided. They are the following. All of them are needed to live in the same directory in order for this to work.

level3.py
level3.flag.txt.enc
level3.hash.bin

Now let's open up the main file which is the level3.py

First, download both the files and store them in the same directory.level2.py and level2.flag.txt.enc

Then use the following command in the terminal to see the contents of the file.

nano level2.py

First, dowload both the files in store them in the same directory. (level1.py and level1.flag.txt.enc).

Open up the level1.py using your favorite editor or with the following command from the terminal.

nano level1.py

### THIS FUNCTION WILL NOT HELP YOU FIND THE FLAG --LT ########################
def str_xor(secret, key):
    #extend key to secret length
    new_key = key
    i = 0
    while len(new_key) < len(secret):
        new_key = new_key + key[i]
        i = (i + 1) % len(key)        
    return "".join([chr(ord(secret_c) ^ ord(new_key_c)) for (secret_c,new_key_c) in zip(secret,new_key)])
###############################################################################

flag_enc = open('level1.flag.txt.enc', 'rb').read()

def level_1_pw_check():
    user_pw = input("Please enter correct password for flag: ")
    if( user_pw == "1e1a"):
        print("Welcome back... your flag, user:")
        decryption = str_xor(flag_enc.decode(), user_pw)
        print(decryption)
        return
    print("That password is incorrect")

level_1_pw_check()

First, click on the button 'Launch Instance'. Then ssh to the remote machine using the presented command. Yours might be with different port or user credentials.

ssh -p 50477 picoplayer@saturn.picoctf.net

Then navigate to the following folder using CLI.

cd /challenge/
cat metadata.json

That's all!

Download the file and use the following command in the terminal.

cat flag;

Run the following command.

nc mercury.picoctf.net 35652

returns an output of numbers in decimal format. We have to create a python script in order to convert from this decimal output to ASCII text.

First save the output to a file named flag.txt

nc mercury.picoctf.net 35652 > flag.txt