3 ms·
It's a funny coincidence that I was just reading this book (https://toc.cryptobook.us/ https://toc.cryptobook.us/), Figure 4.5 on book page 102, that talks abou
by xtacy 7y ago
It's a funny coincidence that I was just reading this book (https://toc.cryptobook.us/ https://toc.cryptobook.us/), Figure 4.5 on book page 102, that talks about this exact issue.
I doubt the author realises that the system must be resistant against a class of attacks (in this case, I believe a chosen plaintext attack). From reading the thread, and comparing it to the example in the book, it seems like the non-uniform patterns in the output highlight a possibility of a CPA.
And of course, the author wants a fully implemented + concrete attack instead of pointing to what's an obvious flaw to the crypto community.
- jascii 7y agoAt some point in the thread the author complains that it isn't fair to point out the repetitive patterns "because the clear-text is all zeroes and this would be masked by actual data"
- jschwartzi 7y agoMy first thought was "what if I wanted to encrypt and transmit all-zeroes as a message?"
- sidewndr46 7y agoSo the author tried to encrypt the null byte, repeated thousands of times? That seems like the most pointless test I could dream up for any processing algorithm. Computes all the primes less than 0? Already. Achieve compression approaching 100% on a string of zeroes? Easy. Losslessly compress an image with all pixels having opacity of 0? Easy
- RL_Quine 7y agoIt’s a good demonstration of failure that might otherwise be masked
- henrikschroder 7y agoIf an all-null message results in a simple/repeating ciphertext, it means that there exists at least one message whose ciphertext leaks information, and that in turns means that there are probably more messages like it, and it's also probable that all messages leak info in varying degrees.
- nkrisc 7y agoWhat good is encryption that only works for some inputs?
- fanf2 7y agoI am slightly disappointed that the crypto book did not use a picture of Tux to demonstrate ECB https://blog.filippo.io/the-ecb-penguin/ https://blog.filippo.io/the-ecb-penguin/