There is a side channel attack against the division used to calculate one of
the modulo inverses in the DSA algorithm. This change takes advantage of the
primality of the modulo and Fermat's little theorem to calculate the inverse
without leaking information.
Thanks to Samuel Weiser for finding and reporting this.
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/7487)
(cherry picked from commit 415c335635)
This extends the recently added ECDSA signature blinding to blind DSA too.
This is based on side channel attacks demonstrated by Keegan Ryan (NCC
Group) for ECDSA which are likely to be able to be applied to DSA.
Normally, as in ECDSA, during signing the signer calculates:
s:= k^-1 * (m + r * priv_key) mod order
In ECDSA, the addition operation above provides a sufficient signal for a
flush+reload attack to derive the private key given sufficient signature
operations.
As a mitigation (based on a suggestion from Keegan) we add blinding to
the operation so that:
s := k^-1 * blind^-1 (blind * m + blind * r * priv_key) mod order
Since this attack is a localhost side channel only no CVE is assigned.
This commit also tweaks the previous ECDSA blinding so that blinding is
only removed at the last possible step.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6522)
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)
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)
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>
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>
Move the dsa_st structure out of the public header file. Add some accessor
functions to enable access to the internal fields, and update all internal
usage to use the new functions.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Stephen Henson <steve@openssl.org>
This adds a new accessor function DSA_SIG_get0.
The customisation of DSA_SIG structure initialisation has been removed this
means that the 'r' and 's' components are automatically allocated when
DSA_SIG_new() is called. Update documentation.
Reviewed-by: Rich Salz <rsalz@openssl.org>
The kinv/r fields in the DSA structure are not used by OpenSSL internally
and should not be used in general.
Reviewed-by: Rich Salz <rsalz@openssl.org>
This was done by the following
find . -name '*.[ch]' | /tmp/pl
where /tmp/pl is the following three-line script:
print unless $. == 1 && m@/\* .*\.[ch] \*/@;
close ARGV if eof; # Close file to reset $.
And then some hand-editing of other files.
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
There are header files in crypto/ that are used by a number of crypto/
submodules. Move those to crypto/include/internal and adapt the
affected source code and Makefiles.
The header files that got moved are:
crypto/cryptolib.h
crypto/md32_common.h
Reviewed-by: Rich Salz <rsalz@openssl.org>
This gets BN_.*free:
BN_BLINDING_free BN_CTX_free BN_FLG_FREE BN_GENCB_free
BN_MONT_CTX_free BN_RECP_CTX_free BN_clear_free BN_free BUF_MEM_free
Also fix a call to DSA_SIG_free to ccgost engine and remove some #ifdef'd
dead code in engines/e_ubsec.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Remove support for SHA0 and DSS0 (they were broken), and remove
the ability to attempt to build without SHA (it didn't work).
For simplicity, remove the option of not building various SHA algorithms;
you could argue that SHA_224/256/384/512 should be kept, since they're
like crypto algorithms, but I decided to go the other way.
So these options are gone:
GENUINE_DSA OPENSSL_NO_SHA0
OPENSSL_NO_SHA OPENSSL_NO_SHA1
OPENSSL_NO_SHA224 OPENSSL_NO_SHA256
OPENSSL_NO_SHA384 OPENSSL_NO_SHA512
Reviewed-by: Richard Levitte <levitte@openssl.org>
This is funny; Ben commented in the source, Matt opend a ticket,
and Rich is doing the submit. Need more code-review? :)
Reviewed-by: Dr. Stephen Henson <steve@openssl.org>
This change updates 8a99cb29 to make the generation of (EC)DSA nonces
using the message digest the default. It also reverts the changes to
(EC)DSA_METHOD structure.
In addition to making it the default, removing the flag from EC_KEY
means that FIPS modules will no longer have an ABI mismatch.
This change adds the option to calculate (EC)DSA nonces by hashing the
message and private key along with entropy to avoid leaking the private
key if the PRNG fails.
Check for selftest failures.
Pairwise consistency test for RSA key generation.
Use some EVP macros instead of EVP functions.
Use minimal FIPS EVP where needed.
Key size restrictions.
