picoCTF

Let's Warm UP

WriteUP NO.1

Category: General Skills
Difficulty: Easy
Author: Sanjay C / Danny Tunitis

Challenge Description

The challenge says:

If I told you a word started with 0x70 in hexadecimal, what would it start with in ASCII?

A scary-looking hexadecimal number? In the first challenge? Obviously the CTF gods wanted to make sure we know how to read numbers before letting us touch the dangerous stuff.

No worries, this is just a tiny ASCII conversion.

Solution

The mysterious value is:

0x70

For people who see 0x and immediately think "I need coffee and a debugger", relax. It just means the number is written in hexadecimal.

So we take:

70 (hex)

and convert it to decimal:

0x70 = 112

Now we ask the ancient artifact known as the ASCII table:

"Hey, what character is number 112?"

The answer:

p

That's it. No hacking, no explosions, no terminal full of green text like in the movies. Just a number becoming a letter.

Flag

The challenge wants the answer in picoCTF format:

picoCTF{answer}

So our flag is:

picoCTF{p}

What We Learned

• Hexadecimal is not a scary alien language.
• ASCII is basically a dictionary that tells computers which numbers become letters.
• Sometimes CTF challenges look complicated just because they wear a fancy 0x costume.

Final Thoughts

A good warm-up indeed. The challenge basically asked:

"Can you convert a number?"

And we answered:

"After years of humans inventing computers, yes, we can turn 70 into p."