Set 1 - Challenge 8

Original Challenge Description from matasano

Detect AES in ECB mode

In this file are a bunch of hex-encoded ciphertexts.

One of them has been encrypted with ECB.

Detect it.

Remember that the problem with ECB is that it is stateless and deterministic; the same 16 byte plaintext block will always produce the same 16 byte ciphertext.

My Solution

• Since one byte represents two nibbles, in our give file we need to find duplicate patterns in the the block of 32. "fold" command  is our friend

• Now what we need to do is get these blocks for every line of the input and see if there are any duplicates. "sort" and "wc" can be used in a loop.

that marks the end of Set 1!