How do I generate random bytes with openssl
?
Another command in openssl
is rand
. We invoke it like this:
$ openssl rand -hex 10
aa27660aa7e186902981
Here, 10
indicates the number of random bytes to print to standard out. -hex
prints those bytes in hex format - 2 characters per byte, so 20 characters.
The output comes from a PRNG. The PRNG is seeded with, amongst other randomness sources, a file at ~/.rnd
. This file contains random bytes:
$ cat ~/.rnd
33k�ɱ��%�*��#Yn�� ]w$Lkn���M|cW@9%V
...
OpenSSL apparently uses this location to store previously-gathered entropy. You can delete it at any time without any ill effects.
Tagged . All content copyright James Fisher 2017. This post is not associated with my employer.