Android: prefer CharArray over String #14
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Feb 27, 2024
...sh-libsodium/src/main/java/com/lambdapioneer/sloth/pwhash_libsodium/LibSodiumArgon2PwHash.kt
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Summary
It is general best practise to minimize the exposure of secrets in memory. As such,
Stringsare not great, as they are immutable and we have to hope for the GC to collect them eventually. On the other hand,CharArraysallow us (even if not guaranteed by the spec) to overwrite their content after usage.This PR changes the API to allow for passing in the user password as a
CharArrayinstead ofStrings. If your code currently usesString, you can simply calltoCharArraywhich will result in identical behaviour.Whether this makes a difference in practise, e.g. against a root-level adversary that can already read memory, is a valid discussion to have. However, there exist at least some people who believe that this is a worthwhile defence-in-depth.
Testplan
Run all tests on a physical device (Pixel 6a) and added a test that ensures we maintain backwards-compatibility.