Pico CTF 2014 – The Valley of Fear

The hard drive may be corrupted, but you were able to recover a small chunk of text. Scribbled on the back of the hard drive is a set of mysterious numbers. Can you discover the meaning behind these numbers? (1, 9, 4) (4, 2, 8) (4, 8, 3) (7, 1, 5) (8, 10, 1)

Hint: Might each set of three numbers represent a word in a message?

ENCRYPTED MESSAGE

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This one is so easy. After seeing those 3 numbers in each bracket, I am immediately thinking that ( x, y, z ) means that x = paragraph, y = row, z = word.

For example, ( 1, 9, 4 ) means paragraph 1, 9 row, and word number 4.

The flag is

Ceremonial plates

Pico CTF 2014 : Substitution

There’s an authorization code for some Thyrin Labs information here, along with someone’s favorite song. But it’s been encrypted! Find the authorization code. encrypted.txt

Hint: You may want to look at what the relative frequencies of letters in english text are.

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The hint said the frequencies of letters in english. So, the first time I saw the encrypted text is 3 characters at the first sentence. Guess what? That must be “The” word. Mark those 3.

And then look at other word that seems familiar. For example, 4 characters word that have T, H and E such as “THEY” and so on.

After figuring out one by one of the substitution cipher. I got the result like this:

THE AUTHORIZATION CODE IS ILLMAKEAMANOUTOFYOULETS

Maybe I got the flag 😉