diff options
| author | Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> | 2019-06-27 10:12:08 +0200 |
|---|---|---|
| committer | Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> | 2019-06-27 14:39:07 +0200 |
| commit | 262c00882a2fd7cf16672bf467a86f75b4098a7c (patch) | |
| tree | 8145f67128e8db9c6a5d39f1da0017e8899231fb /doc/man7/RAND.pod | |
| parent | 0588be2e01c244c41b0215689f411a6223063fd7 (diff) | |
man: clarify the 'random number generator must be seeded' requirement
The manual pages require for some API functions that the 'random number
generator must be seeded' before calling the function. Initially, this
was meant literally, i.e. the OpenSSL CSPRNG had to be seeded manually
before calling these functions.
Since version 1.1.1, the CSPRNG is seeded automatically on first use,
so it's not the responsibility of the programmer anymore. Still, he
needs to be aware that the seeding might fail.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/9257)
Diffstat (limited to 'doc/man7/RAND.pod')
| -rw-r--r-- | doc/man7/RAND.pod | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/doc/man7/RAND.pod b/doc/man7/RAND.pod index 3d4766694e..e253e9025d 100644 --- a/doc/man7/RAND.pod +++ b/doc/man7/RAND.pod @@ -28,6 +28,12 @@ As a normal application developer, you do not have to worry about any details, just use L<RAND_bytes(3)> to obtain random data. Having said that, there is one important rule to obey: Always check the error return value of L<RAND_bytes(3)> and do not take randomness for granted. +Although (re-)seeding is automatic, it can fail because no trusted random source +is available or the trusted source(s) temporarily fail to provide sufficient +random seed material. +In this case the CSPRNG enters an error state and ceases to provide output, +until it is able to recover from the error by reseeding itself. +For more details on reseeding and error recovery, see L<RAND_DRBG(7)>. For values that should remain secret, you can use L<RAND_priv_bytes(3)> instead. |