Fix fread check for reading randomness #384
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Fallback CSPRNG on generic UNIX will read `urandom` for randomness. The read has a bug where if `fread` reads say 10 bytes but the size is 32. The buffer is only partially updated and returned successful. This patch ensures the fallback read returns success only when the buffer is fully filled.
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Pull request overview
This PR fixes a critical bug in the fallback CSPRNG implementation for generic UNIX systems and improves the time resolution for entropy collection. The original fread check incorrectly returned success when ANY bytes were read, even if the buffer was only partially filled, potentially leaving random data incomplete and compromising security.
- Fixed the fread return value check to ensure the buffer is fully filled before returning success
- Improved time resolution from milliseconds to microseconds for better entropy on fallback platforms
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Fallback CSPRNG on generic UNIX will read
urandomfor randomness. The read has a bug where iffreadreads say 10 bytes but the size is 32. The buffer is only partially updated and returned successful.This patch ensures the fallback read returns success only when the buffer is fully filled.
And moving from ms to us resolution for fallback platform because most platforms will have that. ns is more arguable.