Is it really just a block cipher in ECB mode, so that each packet can be decoded without any prior packet⁰?
No. ECB is bad and creating a secure real-time channel (that can even handle packet loss) is a solved problem. It has been for years. There's no good excuse for using ECB here.
Is it a block cipher in some non-ECB mode, but it gets reset at the ...
What is the difference between cfb and cfb1 and cfb8?
Well, first of all, we need examine what CFB is. Here is what the encryption process is:
Take the previous $n$ bits of ciphertext (where $n$ is the block size of the cipher, for Aria, $n=128$
Send it through the block cipher in encryption mode
Extract $k$ bits of the result, exclusive-or that with the ...
What is the name of the mode in which we simply change the tweak for each block without the need for complex chaining modes? Is this mode secure?
Yes, if you do it right it's IND\$-CPA secure but not IND-CCA (and thus not AE-secure). In particular you'd need a CTR-like counter in your tweak (ie block counter + nonce / IV) and then each message block would ...
Many people want a "seekable cipher", which implies that they can't use chaining modes.(a) (b)
So far I've seen 3 ways to build such a cipher:
XTS: "XEX-based tweaked-codebook mode with ciphertext stealing (XTS)" is used in most modern "full-disk encryption" systems. (c)
CTR: "Counter mode (CTR)" (d)
OCB "Offset Codebook Mode (OCB)" (e)
Let's assume that we're talking about the following classic modes for block ciphers (although there are certainly more): ECB, CBC, CFB, OFB and CTR.
First of all the second message is way too long to fit into the ciphertext, so we can safely discard that possibility.
Then we can look at the size of the plaintext and ciphertext. The plaintext message is 14 ...