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: Richard Levitte <levitte@openssl.org>
now use an internal RAND_METHOD. All dependencies to OpenSSL standard
PRNG are now removed: it is the applications resposibility to setup
the FIPS PRNG and initalise it.
Initial OpenSSL RAND_init_fips() function that will setup the DRBG
for the "FIPS capable OpenSSL".
knock-on work than expected - they've been extracted into a patch
series that can be completed elsewhere, or in a different branch,
before merging back to HEAD.
changes are the fallout). As this could break source code that doesn't
directly include headers for interfaces it uses, changes to recursive
includes are covered by the OPENSSL_NO_DEPRECATED symbol. It's better to
define this when building and using openssl, and then adapt code where
necessary - this is how to stay current. However the mechanism exists for
the lethargic.
ENGINE surgery. DH, DSA, RAND, and RSA now use *both* "method" and ENGINE
pointers to manage their hooking with ENGINE. Previously their use of
"method" pointers was replaced by use of ENGINE references. See
crypto/engine/README for details.
Also, remove the ENGINE iterations from evp_test - even when the
cipher/digest code is committed in, this functionality would require a
different set of API calls.
Previously RAND_get_rand_method was returning a non-const pointer, but it
should be const. As with all other such cases, METHOD pointers are stored and
returned as "const". The only methods one should be able to alter are methods
"local" to the relevant code, in which case a non-const handle to the methods
should already exist.
This change has been forced by the constifying of the ENGINE code (before
which RAND_METHOD was the only method pointer in an ENGINE structure that was
not constant).
sure they are available in opensslconf.h, by giving them names starting
with "OPENSSL_" to avoid conflicts with other packages and by making
sure e_os2.h will cover all platform-specific cases together with
opensslconf.h.
I've checked fairly well that nothing breaks with this (apart from
external software that will adapt if they have used something like
NO_KRB5), but I can't guarantee it completely, so a review of this
change would be a good thing.
only queried when the /dev/[u]random devices did not return enough
entropy. Only the amount of entropy missing to reach the required minimum
is queried, as EGD may be drained.
Queried locations are: /etc/entropy, /var/run/egd-pool
"Jan Mikkelsen" <janm@transactionsite.com> correctly states that the
OpenSSL header files have #include's and extern "C"'s in an incorrect
order. Thusly fixed.
returns int (1 = ok, 0 = not seeded). New function RAND_add() is the
same as RAND_seed() but takes an estimate of the entropy as an additional
argument.
