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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/file-format-and-process.md | 8 | ||||
| -rw-r--r-- | doc/os-random-seed-comparison.md | 34 |
2 files changed, 42 insertions, 0 deletions
diff --git a/doc/file-format-and-process.md b/doc/file-format-and-process.md index 6ffc067..0d50cc7 100644 --- a/doc/file-format-and-process.md +++ b/doc/file-format-and-process.md @@ -26,5 +26,13 @@ argument. Check that calling statfs(2) on the random seed file returns a `f_fsid` that when hashed, matches the argument. +## fs-uuid +Check that the UUID of the random seed file system, when hashed as a string, +matches the argument. + +## drive-id +Check that the ID as determined by udev of the random seed file system, when +hashed as a string, matches the argument. + ## done End of mandatory commands. diff --git a/doc/os-random-seed-comparison.md b/doc/os-random-seed-comparison.md new file mode 100644 index 0000000..71ff0c3 --- /dev/null +++ b/doc/os-random-seed-comparison.md @@ -0,0 +1,34 @@ +This is an attempt to document the random seed behavior of different operating +systems. This is based mostly on Goog^WInternet searches. If you believe this +information is incorrect, please submit patches. + +## Linux + +The random seed behavior of Linux is well documented, but we will rehash it +(heh) here for completeness. Linux has three interfaces for random access: +/dev/random, /dev/urandom, and getrandom. /dev/random attempts to keep track of +the entropy count and blocks when it reaches zero. /dev/urandom never blocks. +getrandom blocks during early startup until the entropy count becomes "full". + +## OpenBSD + +OpenBSD has one central RNG for all its randomness. The bootloader seeds the +RNG using random data from installation plus random data obtained from the +OpenBSD servers. Therefore, none of the random interfaces ever block. + +## FreeBSD + +On FreeBSD, /dev/random and /dev/urandom both block until the random seed is +installed. This is defined as the time when a FD opened read-write on +/dev/random is closed. Thereafter, they do not block. + +## Windows + +The exact behavior of the Windows RNG is not publicly documented. It is, +however, known to be seeded in part by a registry value. + +## Mac OS + +Dunno. https://github.com/jedisct1/libsodium/issues/594 says the PRNG is +terrible, then says it's "totally fine". I don't have Mac, and the Mac man +pages are shamefully not accessible online, so I cannot check for myself. |