[palmer]

There is a 172 bit attack on an AES-256 encryption key.

256 bit AES has a 2^119 attack. As Schneier pointed out https://www.schneier.com/blog/archives/2009/07/another_new_aes.html it is impractical, not a threat to AES.

This attack has nothing to do with whether Assange is or is not revealing a 256 bit (or any size) key. His tweet contains 16 bytes of ascii and 16 bytes of binary. The 16 bytes of binary could be a key, or not. He may have a key and may be revealing it, or not.

[lurked_for_a_decade]

There are attacks with a complexity of 2^99 and “reasonable” modifications to it that can get the complexity down to 2^39 under “ideal” conditions.

I think the 172 bit length, if each alph/numeric digit is interpreted as a hex number ( at 4 bits each ) is also interesting when one read the articles I linked to.

It could be merely coincidence that < half of the numbers when viewed 2 at a time correspond to ASCII characters.

The remainder do not correspond to ASCII as evidenced by the letters af present in the provided string. I was just throwing it out there.