Originally suggested solution for "Return Of the Hidden Number Problem"
is arguably too expensive. While it has marginal impact on slower
curves, none to ~6%, optimized implementations suffer real penalties.
Most notably sign with P-256 went more than 2 times[!] slower. Instead,
just implement constant-time BN_mod_add_quick.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6810)
(cherry picked from commit 3fc7a9b96cbed0c3da6f53c08e34d8d0c982745f)
Resolved onflicts:
crypto/ec/ecdsa_ossl.c
crypto/include/internal/bn_int.h
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>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6524)
Keegan Ryan (NCC Group) has demonstrated a side channel attack on an
ECDSA signature operation. During signing the signer calculates:
s:= k^-1 * (m + r * priv_key) mod order
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.
Reviewed-by: Rich Salz <rsalz@openssl.org>
information about the length of the scalar used in ECDSA operations
from a large number (2^32) of signatures.
Thanks to Neals Fournaise, Eliane Jaulmes and Jean-Rene Reinhard for
reporting this issue.
Refer to #4576 for further details.
Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4623)
Submitted by: "Andrzej Chmielowiec" <achmielowiec@enigma.com.pl>, steve@openssl.org
Approved by: steve@openssl.org
Truncate hash if it is too large: as required by FIPS 186-3.
- hide the EC_KEY structure definition in ec_lcl.c + add
some functions to use/access the EC_KEY fields
- change the way how method specific data (ecdsa/ecdh) is
attached to a EC_KEY
- add ECDSA_sign_ex and ECDSA_do_sign_ex functions with
additional parameters for pre-computed values
- rebuild libeay.num from 0.9.7
dh.h, dsa.h, ec.h, ecdh.h, ecdsa.h, rsa.h), as the opaque bignum types are
already declared in ossl_typ.h. Add explicit includes for bn.h in those C
files that need access to structure internals or API functions+macros.
