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39 lines
1.2 KiB
Markdown
39 lines
1.2 KiB
Markdown
## `libent`
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`libent` is a cross-platform wrapper around `getentropy(2)`. It exports
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one symbol, `ent_getentropy`. If getentropy is available, then it's just
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a shim around that. Otherwise, it uses `getrandom(2)` (available since
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kernel 3.17) on Linux, or `/dev/urandom` on other \*nix.
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### Building and Testing
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```bash
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./configure
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make
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make test
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PREFIX=/usr/local make install
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```
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### Why?
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`getentropy` is the wave of the future. It's the correct API for
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generating small amounts of entropy to create cryptographic keys or seed
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PRNGs. It's good and reasonable and true, it's on Linux, \*BSD, and OS
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X, and it only took us fifty years of UNIX to get here.
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Sadly, it only just arrived, so nobody has it yet. It didn't land in
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Linux until glibc 2.25, which seems to only have made it into Debian 10.
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Once `getentropy` is everywhere you care about, you can just do a
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s/ent\_//g on all the call sites and discard this shim.
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This project began because [Urbit](https://github.com/urbit/urbit)'s
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entropy-generation function was bothering me. Then it got out of hand.
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### References
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* [OpenBSD getentropy](https://man.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man2/getentropy.2)
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* [djb on entropy gathering](https://blog.cr.yp.to/20140205-entropy.html)
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