The RAND_DRBG API was added in PR #5462 and modified by PR #5547.
This commit adds the corresponding documention.
Reviewed-by: NKurt Roeckx <kurt@roeckx.be>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5461)

Add a new global DRBG for private keys used by RAND_priv_bytes.

Add BN_priv_rand() and BN_priv_rand_range() which use RAND_priv_bytes().
Change callers to use the appropriate BN_priv... function.
Reviewed-by: NPaul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/4076)

And BN_pseudo_rand_range is really BN_rand_range.
Document that we might deprecate those functions.
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3743)

Fix a =head1 section name
Fix a typo in POD label
Remove a spurious =back
Add a missing blank line
Avoid 'legacy' -- use 'deprecated' if still needed if we cannot just reword.
Always do strict checking
Do not warn about missing "RETURN VALUES" unless -s is set.
Change OpenSSL version 1.1 -> 1.1.0
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3830)

Reviewed-by: NBen Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/3773)

See old GitHub PR 38.
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3714)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1900)

Move manpages to manX directories
Add Windows/VMS install fix from Richard Levitte
Update README
Fix typo's
Remove some duplicates
Reviewed-by: NRichard Levitte <levitte@openssl.org>

Fix some code examples, trailing whitespace
Fix TBA sections in verify, remove others.
Remove empty sections
Use Mixed Case not ALL CAPS in head2
Enhance doc-nits script.
Remove extra =cut line
Reviewed-by: NRichard Levitte <levitte@openssl.org>

Reviewed-by: NRichard Levitte <levitte@openssl.org>

Provide backwards-compatiblity for functions, macros and include
files if OPENSSL_API_COMPAT is either not defined or defined less
than the version number of the release in which the feature was
deprecated.
Reviewed-by: NRichard Levitte <levitte@openssl.org>

If something was "present in all versions" of SSLeay, or if it was
added to a version of SSLeay (and therefore predates OpenSSL),
remove mention of it.  Documentation history now starts with OpenSSL.

Remove mention of all history before OpenSSL 0.9.8, inclusive.

Remove all AUTHOR sections.
Reviewed-by: NTim Hudson <tjh@openssl.org>

L<foo|foo> is sub-optimal  If the xref is the same as the title,
which is what we do, then you only need L<foo>.  This fixes all
1457 occurrences in 349 files.  Approximately.  (And pod used to
need both.)
Reviewed-by: NRichard Levitte <levitte@openssl.org>

The justification for RAND_pseudo_bytes is somewhat dubious, and the reality
is that it is frequently being misused. RAND_bytes and RAND_pseudo_bytes in
the default implementation both end up calling ssleay_rand_bytes. Both may
return -1 in an error condition. If there is insufficient entropy then
both will return 0, but RAND_bytes will additionally add an error to the
error queue. They both return 1 on success.
Therefore the fundamental difference between the two is that one will add an
error to the error queue with insufficient entory whilst the other will not.
Frequently there are constructions of this form:

if(RAND_pseudo_bytes(...) <= 1)
	goto err;

In the above form insufficient entropy is treated as an error anyway, so
RAND_bytes is probably the better form to use.

This form is also seen:
if(!RAND_pseudo_bytes(...))
	goto err;

This is technically not correct at all since a -1 return value is
incorrectly handled - but this form will also treat insufficient entropy as
an error.

Within libssl it is required that you have correctly seeded your entropy
pool and so there seems little benefit in using RAND_pseudo_bytes.
Similarly in libcrypto many operations also require a correctly seeded
entropy pool and so in most interesting cases you would be better off
using RAND_bytes anyway. There is a significant risk of RAND_pseudo_bytes
being incorrectly used in scenarios where security can be compromised by
insufficient entropy.

If you are not using the default implementation, then most engines use the
same function to implement RAND_bytes and RAND_pseudo_bytes in any case.

Given its misuse, limited benefit, and potential to compromise security,
RAND_pseudo_bytes has been deprecated.
Reviewed-by: NRichard Levitte <levitte@openssl.org>

manual when the specific function is refered to in the current manual text.
This correction was originally introduced in OpenBSD's tracking of OpenSSL.

Slightly clarify the RAND_... documentation.