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)
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)
Add a new config param to specify how the CSPRNG should be seeded.
Illegal values or nonsensical combinations (e.g., anything other
than "os" on VMS or HP VOS etc) result in build failures.
Add RDSEED support.
Add RDTSC but leave it disabled for now pending more investigation.
Refactor and reorganization all seeding files (rand_unix/win/vms) so
that they are simpler.
Only require 128 bits of seeding material.
Many document improvements, including why to not use RAND_add() and the
limitations around using load_file/write_file.
Document RAND_poll().
Cleanup Windows RAND_poll and return correct status
More completely initialize the default DRBG.
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/3965)
Looking at
http://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-90Ar1.pdf
we see that in the CTR_DRBG_Update() algorithm (internal page number 51),
the provided input data is (after truncation to seedlen) xor-d with the
key and V vector (of length keylen and blocklen respectively). The comment
in ctr_XOR notes that xor-ing with 0 is the identity function, so we can
just ignore the case when the provided input is shorter than seedlen.
The code in ctr_XOR() then proceeds to xor the key with the input, up
to the amount of input present, and computes the remaining input that
could be used to xor with the V vector, before accessing a full 16-byte
stretch of the input vector and ignoring the calculated length. The correct
behavior is to respect the supplied input length and only xor the
indicated number of bytes.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3971)
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)
