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There are probably quite a few good reasons for this, although I don't expect that a scientific answer can be composed (as you would need to use a survey, and I've never heard of such a thing for modes of operation). Let me list a few possible reasons: Developers don't know about CTR mode of operation; most questions on StackOverflow are about ECB and CBC ...


3

A message encrypted with AES-GCM can be decrypted with an AES-CTR library IF the authentication tag is stripped from the message. If you are encrypting with AES-GCM and then adding an HMAC tag, you need to strip the HMAC and the GTAG off the message in order to decrypt it, assuming the IV section of the message is in the correct location for each library to ...


1

It doesn't make too much sense at all to send the IV together with the key. The whole idea of an IV is that it is unique per key. But if the key changes value each time, then any IV is unique. So you could use a static IV or even an IV that consists of all zeros. In that case you only need to worry that you don't reuse the key at other locations in the ...


0

Normally you would e.g. prepend the IV to the cipher text as fgrieu suggested. But it would also be fine to send the IV together with the secret key in case they are bound to message sent. You would normally use prepending when sending several messages with the same key but of course different IVs. Thus the key has to be send securely only once whereas you ...


0

You want convergent encryption. I recommend you use an existing scheme for convergent encryption, such as the scheme used by Tahoe-LAFS, rather than trying to invent your own. There are multiple such schemes. See also https://tahoe-lafs.org/hacktahoelafs/drew_perttula.html.


1

I cannot prove that your scheme is secure, but as far as I know, a non-cryptographic hash function would work fine as there is an infinite number of inputs to any given hash, making it impossible to bruteforce all but the shortest messages (which would be an issue for short messages, you may want to append some sort of 128-bit padding). However, that said, ...



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