Hard Live

We want Nudes instead of Nukes

90 points

134 Solves

Cryptography

Hard

macmueller

Community Rating: 4.57 / 5

Donald has gone completely crazy. To prevent world chaos, you kidnapped him. Right before the kidnapping he tried to send one encrypted message to his wife Melania. Luckily you intercepted the message. Donald admits that he used AES-CBC encryption - a block cipher operating with a block length of 16 bytes. (here represented by 32 characters)<br /> The message was: {391e95a15847cfd95ecee8f7fe7efd66,8473dcb86bc12c6b6087619c00b6657e}

The format contains first the Initialization vector(IV) and then the cipher text(c) separated by a colon all wrapped in curly braces. {IV,c} After torturing him by stealing his hairpiece, he tells you the plain text of the message is:

FIRE_NUKES_MELA!

As a passionate hacker you of course try to take advantage of this message. To get the flag alter the message that Melania will read: SEND_NUDES_MELA!

Submit the flag in the format: flag{IV,c}

The characters are hexlified, and one byte is represented by two characters; e.g. the string "84" represents the character "F" of the message and so on.

First 10 Solvers

Rank Username
1 vidar
2 blakeks4711
3 kronos
4 bakkka
5 byte_predator
Rank Username
6 lamchcl
7 Yeraisci
8 HIGH0101
9 samanshf
10 123abcd

  • Lyzeum

    CanĀ“t figure this one out :/ Is there even a way to recover the key by knowing the plain-encrypted-text with AES? Or am I missing something?

    • SunTzu

      You do not need to recover the key. Look what IV is used for...

  • IT_Oracle

    That challenge was very fun! Thanks for teaching me a bit about AES!

  • mhase

    You tell a nice story there. Still relevant, unfortunately.

    Challenge was fun. :)