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Correct information regarding symmetric keys
I forgot to add salt. Thanks u/RisenSteam.
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@ -30,10 +30,15 @@ A good measure of password strength is *entropy bits.* The entropy bits in a pas
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A brute-force attack that executes 2ⁿ guesses is certain to crack a password with n entropy bits, and has a one-in-two chance of cracking a password with n+1 entropy bits.
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For scale, AES 256 encryption is currently the industry standard for strong symmetric encryption. As the name suggests, its keys have 256 bits of entropy; if your password has more than 256 entropy bits, then the AES-256 encryption algorithm is the bottleneck.
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For scale, AES 256 encryption is currently the industry standard for strong symmetric encryption.
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=> https://en.wikipedia.org/wiki/Advanced_Encryption_Standard Advanced Encryption Standard (Wikipedia)
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As the name suggests, its keys have 256 bits of entropy. Be aware that AES keys are typically derived from key derivation functions that salt and hash passwords, so a brute-force attack to discover the password from an AES key would be against such a function. Perhaps I could address that in a future article.
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=> https://en.wikipedia.org/wiki/Key_derivation_function Key derivation function (Wikipedia)
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=> https://en.wikipedia.org/wiki/Salt_(cryptography) Salt (cryptography) (Wikipedia)
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To calculate the entropy of a password, I recommend using a tool such as zxcvbn or KeePassXC.
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=> https://www.usenix.org/conference/usenixsecurity16/technical-sessions/presentation/wheeler zxcvbn: Low-Budget Password Strength Estimation
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@ -272,7 +277,7 @@ A publication⁵ by Seth Lloyd from MIT further explores limits to computation s
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## Acknowledgements
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Thanks to Barna Zsombor and Ryan Coyler for helping me over IRC with my shaky physics and pointing out the caveats of my approach.
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Thanks to Barna Zsombor and Ryan Coyler for helping me over IRC with my shaky physics and pointing out the caveats of my approach. u/RisenSteam on Reddit also corrected my reference to AES-256 encryption by bringing up salts.
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My notes from Thermal Physics weren't enough to write this; various Wikipedia articles were also quite helpful, most of which were linked in the body of the article.
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@ -69,8 +69,12 @@ with *n*+1 entropy bits.
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For scale, [AES-256](https://en.wikipedia.org/wiki/Advanced_Encryption_Standard)
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encryption is currently the industry standard for strong symmetric encryption. As the
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name suggests, its keys have 256 bits of entropy; if your password has more than 256
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entropy bits, then the AES-256 encryption algorithm is the bottleneck.
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name suggests, its keys have 256 bits of entropy. Be aware that AES keys are
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typically derived from [key derivation
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functions](https://en.wikipedia.org/wiki/Key_derivation_function) that
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[salt](https://en.wikipedia.org/wiki/Salt_(cryptography)) and hash passwords, so a
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brute-force attack to discover the password from an AES key would be against such a
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function. Perhaps I could address that in a future article.
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To calculate the entropy of a password, I recommend using a tool such as
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[zxcvbn](https://www.usenix.org/conference/usenixsecurity16/technical-sessions/presentation/wheeler)
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@ -339,7 +343,8 @@ Acknowledgements
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Thanks to [Barna Zsombor](http://bzsombor.web.elte.hu/) and [Ryan
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Coyler](https://rcolyer.net/) for helping me over IRC with my shaky physics and
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pointing out the caveats of my approach.
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pointing out the caveats of my approach. u/RisenSteam on Reddit also corrected my
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reference to AES-256 encryption by bringing up salts.
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My notes from Thermal Physics weren't enough to write this; various Wikipedia
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articles were also quite helpful, most of which were linked in the body of the
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