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Comment by willglynn | Hacker News Reader

You don't need to break SHA256 to de-anonymize these values.

`awless` collects account number hashes. AWS account numbers are 12 decimal digits long, meaning there's a total of 10^12 unique values. Values are anonymized before submission using a single round of SHA256, so in ~2^40 hash operations, anyone with your database of hashes can invert every single account number.

For comparison, the bitcoin blockchain presently has a hash rate of ~2^61 SHA256 hashes per second. (Edit: I incorrectly stated 2^41 based on a hash rate of 3 TH/s, when it's actually 3 million TH/s.)

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On my not-so-special spare server, I'm able to pregenerate the hashes with that fixed salt at 344,191 per second. So, it would take only about a month to compute them for every 12 digit AWS account number. And, as mentioned, that's on my not-so-fast spare server, running in one process, one thread.

acct [000003441910] has hash [d2a52833a6e434d2a55be0ce852c2dd9c5260c49a7c28ea4fa3fe2ac6d054d7e] (the last one it finished in 10 seconds)

A little effort with a decent GPU + hashcat though, would take this exercise down to a few minutes.

Good point. Thanks for the advice, we will study quickly how we can improve this. Our goal is above all to make the usage of AWS easier, and as a result, more secure. We do not want to expose the CLI users to any new threat. We made the source code available to anyone (even the anonymous data collection), to be transparent and get feedback on our work to correct it when needed.

I opened an issue:

https://github.com/wallix/awless/issues/39

PBKDF2, bcrypt, and scrypt are all used where a database needs to store something and check for equality, but where the values in the database need to not be reversible even if the database is breached. They might be suitable here.

None of those can deal with the case of having too limited of an input range. Even if you use a million rounds, you've only added 2^20 to the workload.

Different algo, but my 970 can perform 3.4 billon SHA1 hashes per second on the low setting in hashcat

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