Description
I’ve been sitting here for days, listening to the radio and writing down dots and dashes. I’m starting to feel like one of those old-timey codebreakers, you know? To be honest, I have no idea what it all means! Think you can help me out? (100 points)
Given file: 1N73rC3P710N.enc
Writeup
Upon opening the file, it appears to be morse code with dots . and dashes -
Let’s open up CyberChef and slap our morse code as the input with the From Morse Code recipe
Our decoded morse code is a bunch of T and F in groups of 8. Looks a lot like binary so lets replace T -> 1 and F -> 0. Use Find / Replace recipes and drag them below our previous recipe.
After replacement of 0s and 1s use a From Binary with Space delimiter and byte length of 8
Whenever you see an equal sign at the end of a bunch of random alphabetic characters, it usually means that the string is encoded with base 64, but let’s use the magic recipe that tries a bunch of decoding methods.
You can see it’s suggesting the From Base64 recipe. Click the suggestion to load it.
Our output is now: 80.85.51.70.75.77.75.83.74.73.50.72.83.83.83.55.71.52.90.84.77.88.90.86.80.69.90.86.69.78.66.84.80.69.52.70.54.77.50.76.71.66.70.72.87.84.75.66.74.74.87.72.69.52.68.68
Those numbers look to be in the range of 32-127 which is the range of ASCII printable character codes which means we need a From Decimal recipe. The From Decimal recipe doesn’t support dot . as a delimiter.
So, let’s find and replace again. Replacing dot with comma, since it’s a supported delimiter. \. -> ,
Now we can use From Decimal:
After using Magic again, it suggests From Base32 so let’s insert that.
The result is }6U1RJ4yJ_736_5y3R43y8_3K0J{MAJlrpc
Remember the flag format is vikeCTF{}. We can see that there is 7 characters after { at the very end. 3 of which are lower-case with 4 upper. Just enough for vikeCTF but in reverse!
Apply the Reverse recipe to get cprlJAM{J0K3_8y34R3y5_637_Jy4JR1U6}
Seems like if we apply magic again, there is no suggestions. Let’s try a cipher identifier
The strongest suggestions are Affine Cipher and Mono-alphabetic Substitution. Let’s try Affine Cipher first. After entering our cipher text, click on Auto Brute Force Decryption.
ctrl + F for vike and voila! Among the hundreds of results, we see our flag.
Flag
vikeCTF{C0D3_8r34K3r5_637_Cr4CK1N6}
Personal note
I’m a big F1 fan and today’s FIA judgement was abysmal (as always), demoting Alonso to 4th place after they took 2hrs to analyze a single jpeg. But Alonso is GOATED so he still celebrated his podium. EDIT: LOOKS LIKE THEY GAVE 3RD BACK TO HIM YAYY!