logoalt Hacker News

tptacektoday at 3:42 AM2 repliesview on HN

Symmetric cryptography isn't based on complicated math the way asymmetric cryptography it is. The right way to think about symmetric cryptography is that the core hard problem is simply making PLAINTEXT XOR KEY work, efficiently, with a key that repeats.


Replies

stingraycharlestoday at 4:09 AM

Isn’t another aspect of it that it’s sufficiently random / unrecognizable, for example?

I’m very much aware of the differences between symmetric and asymmetric encryption, and realize that symmetric encryption is much simpler, but I figure that if there are weaknesses to be found in algorithms such as md5, then surely there are also potential weaknesses in symmetric encryption algorithms?

Now I’m not saying that this would be the case for battle tested algorithms like AES. But is there any particular reason why this whole category could not possibly have weaknesses?

show 1 reply
kadobantoday at 4:14 AM

> with a key that repeats

There's a _lot_ hiding in that, all of the interesting stuff for security and potential breaks. So...yeah it is based on complicated math, it's just in that bit instead of the xor.

Even the xor is a bit of a fudge, but probably close enough.

show 1 reply