There are two undocumented DSA parameter generation options available in
the genpkey command line app:
dsa_paramgen_md and dsa_paramgen_q_bits.
These can also be accessed via the EVP API but only by using
EVP_PKEY_CTX_ctrl() or EVP_PKEY_CTX_ctrl_str() directly. There are no
helper macros for these options.
dsa_paramgen_q_bits sets the length of q in bits (default 160 bits).
dsa_paramgen_md sets the digest that is used during the parameter
generation (default SHA1). In particular the output length of the digest
used must be equal to or greater than the number of bits in q because of
this code:
if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
goto err;
if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
goto err;
for (i = 0; i < qsize; i++)
md[i] ^= buf2[i];
/* step 3 */
md[0] |= 0x80;
md[qsize - 1] |= 0x01;
if (!BN_bin2bn(md, qsize, q))
goto err;
qsize here is the number of bits in q and evpmd is the digest set via
dsa_paramgen_md. md and buf2 are buffers of length SHA256_DIGEST_LENGTH.
buf2 has been filled with qsize bits of random seed data, and md is
uninitialised.
If the output size of evpmd is less than qsize then the line "md[i] ^=
buf2[i]" will be xoring an uninitialised value and the random seed data
together to form the least significant bits of q (and not using the
output of the digest at all for those bits) - which is probably not what
was intended. The same seed is then used as an input to generating p. If
the uninitialised data is actually all zeros (as seems quite likely)
then the least significant bits of q will exactly match the least
significant bits of the seed.
This problem only occurs if you use these undocumented and difficult to
find options and you set the size of q to be greater than the message
digest output size. This is for parameter generation only not key
generation. This scenario is considered highly unlikely and
therefore the security risk of this is considered negligible.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5800)
information about the length of a value used in DSA operations from
a large number of signatures.
This doesn't rate as a CVE because:
* For the non-constant time code, there are easier ways to extract
more information.
* For the constant time code, it requires a significant number of signatures
to leak a small amount of information.
Thanks to Neals Fournaise, Eliane Jaulmes and Jean-Rene Reinhard for
reporting this issue.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4576)
Since return is inconsistent, I removed unnecessary parentheses and
unified them.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4541)
Names were not removed.
Some comments were updated.
Replace Andy's address with openssl.org
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/4516)
Removed e_os.h from all bar three headers (apps/apps.h crypto/bio/bio_lcl.h and
ssl/ssl_locl.h).
Added e_os.h into the files that need it now.
Directly reference internal/nelem.h when required.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4188)
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: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/4076)
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)
Run perltidy on util/mkerr
Change some mkerr flags, write some doc comments
Make generated tables "const" when genearting lib-internal ones.
Add "state" file for mkerr
Renerate error tables and headers
Rationalize declaration of ERR_load_XXX_strings
Fix out-of-tree build
Add -static; sort flags/vars for options.
Also tweak code output
Moved engines/afalg to engines (from master)
Use -static flag
Standard engine #include's of errors
Don't linewrap err string tables unless necessary
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3392)
Replace all remaining uses of LONG and ZLONG with INT32 / ZINT32.
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3126)
When setting the digest parameter for DSA parameter generation, the
signature MD was set instead of the parameter generation one.
Fortunately, that's also the one that was used for parameter
generation, but it ultimately meant the parameter generator MD and the
signature MD would always be the same.
Fixes github issue #2016
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2250)
Both strdup or malloc failure should raise à err.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1905)
prio openssl 1.1.0 seed_len < q was accepted and the seed argument was
then ignored. Now DSA_generate_parameters_ex() returns an error in such
a case but no error string.
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1657)
We should check the last BN_CTX_get() call to ensure that it isn't NULL
before we try and use any of the allocated BIGNUMs.
Issue reported by Shi Lei.
Reviewed-by: Richard Levitte <levitte@openssl.org>
To avoid having to immediately free up r/s when setting them
don't allocate them automatically in DSA_SIG_new() and ECDSA_SIG_new().
RT#4590
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reorder arguments to follow convention.
Also allow r/s to be NULL in DSA_SIG_get0, similarly to ECDSA_SIG_get0.
This complements GH1193 which adds non-const setters.
Reviewed-by: Rich Salz <rsalz@openssl.org>
SSH2 implementations which use DSA_do_verify() and ECDSA_do_verify() are given
the R and S values, and the data to be signed, by the client. Thus in order
to validate these signatures, SSH2 implementations will digest and sign
the data -- and then pass in properly provisioned DSA_SIG and ECDSA_SIG objects.
Unfortunately, the existing OpenSSL-1.1.0 APIs do not allow for directly setting
those R and S values in these objects, which makes using OpenSSL for such
SSH2 implementations much more difficult.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1193)
The flags RSA_FLAG_NO_CONSTTIME, DSA_FLAG_NO_EXP_CONSTTIME and
DH_FLAG_NO_EXP_CONSTTIME which previously provided the ability to switch
off the constant time implementation for RSA, DSA and DH have been made
no-ops and deprecated.
Reviewed-by: Richard Levitte <levitte@openssl.org>
The dsa_ossl.c file defined a couple of multi-line macros, but then only
used each one once. The macros just serve to complicate the code and make
it more difficult to understand what is really going on. Hence they are
removed.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Operations in the DSA signing algorithm should run in constant time in
order to avoid side channel attacks. A flaw in the OpenSSL DSA
implementation means that a non-constant time codepath is followed for
certain operations. This has been demonstrated through a cache-timing
attack to be sufficient for an attacker to recover the private DSA key.
CVE-2016-2178
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Add missing error raise call, as it is done everywhere else.
and as CRYPTO_THREAD_lock_new don't do it internally.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Don't copy parameters is they're already present in the destination.
Return error if an attempt is made to copy different parameters to
destination. Update documentation.
If key type is not initialised return missing parameters
RT#4149
Reviewed-by: Richard Levitte <levitte@openssl.org>
