Commit 5b4cb385c1 (#7382) introduced a bug which had the effect
that RAND_add()/RAND_seed() failed for buffer sizes less than
32 bytes. The reason was that now the added random data was used
exlusively as entropy source for reseeding. When the random input
was too short or contained not enough entropy, the DRBG failed
without querying the available entropy sources.
This commit makes drbg_add() act smarter: it checks the entropy
requirements explicitely. If the random input fails this check,
it won't be added as entropy input, but only as additional data.
More precisely, the behaviour depends on whether an os entropy
source was configured (which is the default on most os):
- If an os entropy source is avaible then we declare the buffer
content as additional data by setting randomness to zero and
trigger a regular reseeding.
- If no os entropy source is available, a reseeding will fail
inevitably. So drbg_add() uses a trick to mix the buffer contents
into the DRBG state without forcing a reseeding: it generates a
dummy random byte, using the buffer content as additional data.
Related-to: #7449
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7456)
In pull request #4328 the seeding of the DRBG via RAND_add()/RAND_seed()
was implemented by buffering the data in a random pool where it is
picked up later by the rand_drbg_get_entropy() callback. This buffer
was limited to the size of 4096 bytes.
When a larger input was added via RAND_add() or RAND_seed() to the DRBG,
the reseeding failed, but the error returned by the DRBG was ignored
by the two calling functions, which both don't return an error code.
As a consequence, the data provided by the application was effectively
ignored.
This commit fixes the problem by a more efficient implementation which
does not copy the data in memory and by raising the buffer the size limit
to INT32_MAX (2 gigabytes). This is less than the NIST limit of 2^35 bits
but it was chosen intentionally to avoid platform dependent problems
like integer sizes and/or signed/unsigned conversion.
Additionally, the DRBG is now less permissive on errors: In addition to
pushing a message to the openssl error stack, it enters the error state,
which forces a reinstantiation on next call.
Thanks go to Dr. Falko Strenzke for reporting this issue to the
openssl-security mailing list. After internal discussion the issue
has been categorized as not being security relevant, because the DRBG
reseeds automatically and is fully functional even without additional
randomness provided by the application.
Fixes#7381
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7382)
In drbgtest, test_set_defaults changes the default DRBGs. This works fine
when tests are run in the normal order. However if
OPENSSL_TEST_RAND_ORDER is defined then it may fail (dependent on the
ordering). This environment variable is defined for one of the Travis
tests, so this issue was causing intermittent travis test failures.
[extended tests]
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7338)
- drbg_lib.c: Silence coverity warning: the comment preceding the
RAND_DRBG_instantiate() call explicitely states that the error
is ignored and explains the reason why.
- drbgtest: Add checks for the return values of RAND_bytes() and
RAND_priv_bytes() to run_multi_thread_test().
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5976)
If a nonce is required and the get_nonce callback is NULL, request 50%
more entropy following NIST SP800-90Ar1 section 9.1.
Reviewed-by: Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
GH: #5503
[extended tests]
The test_rand_reseed assumed that the global DRBGs were not used
previously. This assumption is false when the tests are executed
in random order (OPENSSL_TEST_RAND_ORDER). So we uninstantiate
them first and add a test for the first instantiation.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5680)
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/5547)
The NIST standard presents two alternative ways for seeding the
CTR DRBG, depending on whether a derivation function is used or not.
In Section 10.2.1 of NIST SP800-90Ar1 the following is assessed:
The use of the derivation function is optional if either an
approved RBG or an entropy source provides full entropy output
when entropy input is requested by the DRBG mechanism.
Otherwise, the derivation function shall be used.
Since the OpenSSL DRBG supports being reseeded from low entropy random
sources (using RAND_POOL), the use of a derivation function is mandatory.
For that reason we change the default and replace the opt-in flag
RAND_DRBG_FLAG_CTR_USE_DF with an opt-out flag RAND_DRBG_FLAG_CTR_NO_DF.
This change simplifies the RAND_DRBG_new() calls.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5294)
The DRGB concept described in NIST SP 800-90A provides for having different
algorithms to generate random output. In fact, the FIPS object module used to
implement three of them, CTR DRBG, HASH DRBG and HMAC DRBG.
When the FIPS code was ported to master in #4019, two of the three algorithms
were dropped, and together with those the entire code that made RAND_DRBG
generic was removed, since only one concrete implementation was left.
This commit restores the original generic implementation of the DRBG, making it
possible again to add additional implementations using different algorithms
(like RAND_DRBG_CHACHA20) in the future.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4998)
Every DRBG now supports automatic reseeding not only after a given
number of generate requests, but also after a specified time interval.
Signed-off-by: Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/4402)
A third shared DRBG is added, the so called master DRBG. Its sole purpose
is to reseed the two other shared DRBGs, the public and the private DRBG.
The randomness for the master DRBG is either pulled from the os entropy
sources, or added by the application using the RAND_add() call.
The master DRBG reseeds itself automatically after a given number of generate
requests, but can also be reseeded using RAND_seed() or RAND_add().
A reseeding of the master DRBG is automatically propagated to the public
and private DRBG. This construction fixes the problem, that up to now
the randomness provided by RAND_add() was added only to the public and
not to the private DRBG.
Signed-off-by: Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/4402)
Reseeding is handled very differently by the classic RAND_METHOD API
and the new RAND_DRBG api. These differences led to some problems when
the new RAND_DRBG was made the default OpenSSL RNG. In particular,
RAND_add() did not work as expected anymore. These issues are discussed
on the thread '[openssl-dev] Plea for a new public OpenSSL RNG API'
and in Pull Request #4328. This commit fixes the mentioned issues,
introducing the following changes:
- Replace the fixed size RAND_BYTES_BUFFER by a new RAND_POOL API which
facilitates collecting entropy by the get_entropy() callback.
- Don't use RAND_poll()/RAND_add() for collecting entropy from the
get_entropy() callback anymore. Instead, replace RAND_poll() by
RAND_POOL_acquire_entropy().
- Add a new function rand_drbg_restart() which tries to get the DRBG
in an instantiated state by all means, regardless of the current
state (uninstantiated, error, ...) the DRBG is in. If the caller
provides entropy or additional input, it will be used for reseeding.
- Restore the original documented behaviour of RAND_add() and RAND_poll()
(namely to reseed the DRBG immediately) by a new implementation based
on rand_drbg_restart().
- Add automatic error recovery from temporary failures of the entropy
source to RAND_DRBG_generate() using the rand_drbg_restart() function.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4328)
Unlike the NIST DRBG standard, entropy counts are in bits and
buffer lengths are in bytes. This has lead to some confusion and
errors in the past, see my comment on PR 3789.
To clarify the destinction between entropy counts and buffer lengths,
a 'len' suffix has been added to all member names of RAND_DRBG which
represent buffer lengths:
- {min,max}_{entropy,adin,nonce,pers}
+ {min,max}_{entropy,adin,nonce,pers}len
This change makes naming also more consistent, as can be seen in the
diffs, for example:
- else if (adinlen > drbg->max_adin) {
+ else if (adinlen > drbg->max_adinlen) {
Also replaced all 'ent's by 'entropy's, following a suggestion of Paul Dale.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4266)
Apart from ssltest_old.c, the test suite relied on e_os.h for the
OSSL_NELEM macro and nothing else.
The ssltest_old.c also requires EXIT and some socket macros.
Create a new header to define the OSSL_NELEM macro and use that instead.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4186)
If RAND_add wraps around, XOR with existing. Add test to drbgtest that
does the wrap-around.
Re-order seeding and stop after first success.
Add RAND_poll_ex()
Use the DF and therefore lower RANDOMNESS_NEEDED. Also, for child DRBG's,
mix in the address as the personalization bits.
Centralize the entropy callbacks, from drbg_lib to rand_lib.
(Conceptually, entropy is part of the enclosing application.)
Thanks to Dr. Matthias St Pierre for the suggestion.
Various code cleanups:
-Make state an enum; inline RANDerr calls.
-Add RAND_POLL_RETRIES (thanks Pauli for the idea)
-Remove most RAND_seed calls from rest of library
-Rename DRBG_CTX to RAND_DRBG, etc.
-Move some code from drbg_lib to drbg_rand; drbg_lib is now only the
implementation of NIST DRBG.
-Remove blocklength
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/4019)
that needed test_main now works using the same infrastructure as tests that used
register_tests.
This meant:
* renaming register_tests to setup_tests and giving it a success/failure return.
* renaming the init_test function to setup_test_framework.
* renaming the finish_test function to pulldown_test_framework.
* adding a user provided global_init function that runs before the test frame
work is initialised. It returns a failure indication that stops the stest.
* adding helper functions that permit tests to access their command line args.
* spliting the BIO initialisation and finalisation out from the test setup and
teardown.
* hiding some of the now test internal functions.
* fix the comments in testutil.h
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3953)
Ported from the last FIPS release, with DUAL_EC and SHA1 and the
self-tests removed. Since only AES-CTR is supported, other code
simplifications were done. Removed the "entropy blocklen" concept.
Moved internal functions to new include/internal/rand.h.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/3789)
