Used RAND_priv_bytes_ex instead of RAND_bytes_ex to guarantee higher isolation
for cryptographic keys.
Replaced OPENSSL_free with OPENSSL_clear_free to wipe sensitive data and free
it.
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Paul Yang <kaishen.yy@antfin.com>
(Merged from https://github.com/openssl/openssl/pull/27029)
50f945117c