This question already has an answer here:
- Is applying AES multiple times safer? 3 answers
If I had to store a text file with some confidential information on the cloud, would encrypting the file multiple times (say, 3) with different passwords using WinRAR (AES with a 256 bit key) provide more security than encrypting it just once?
I'm assuming that someone will eventually break into this service or my account on the cloud service and gain access to the encrypted data.
I'm also assuming that the current version of the software used (WinRAR 5.11) is secure and doesn't have any vulnerabilities that can be exploited to make password bruteforcing easier (e.g. under 1 hour for WinZip 8 and earlier versions)
EDIT: I checked the linked question, but I'm not referring to the key derivation function (KDF) used. If I understand correctly, in the linked question, the password is only used once and KeePass does a few things to slow down a bruteforce attack using rainbow tables with the KDF.
What if all the three passwords that I use for each of the 3 rounds of encryption are fairly strong and different from each other? And even if KDF is used here (seems like it is), it's used separately on each of the three different passwords.
(e.g. AES256(password3, AES256(password2, AES256(password1, data)))))
Does that make it more or less secure if hardware 'accelerator' beasts like this one try to attack it?