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8b44198b91
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Nicola Tuveri 8b44198b91 Make BN_num_bits() consttime upon BN_FLG_CONSTTIME 
This issue was partially addressed by commit
972c87dfc7, which hardened its callee
BN_num_bits_word() to avoid leaking the most-significant word of its
argument via branching and memory access pattern.
The commit message also reported:
> There are a few places where BN_num_bits is called on an input where
> the bit length is also secret. This does *not* fully resolve those
> cases as we still only look at the top word.

BN_num_bits() is called directly or indirectly (e.g., through
BN_num_bytes() or BN_bn2binpad() ) in various parts of the `crypto/ec`
code, notably in all the currently supported implementations of scalar
multiplication (in the generic path through ec_scalar_mul_ladder() as
well as in dedicated methods like ecp_nistp{224,256,521}.c and
ecp_nistz256.c).

Under the right conditions, a motivated SCA attacker could retrieve the
secret bitlength of a secret nonce through this vulnerability,
potentially leading, ultimately, to recover a long-term secret key.

With this commit, exclusively for BIGNUMs that are flagged with
BN_FLG_CONSTTIME, instead of accessing only bn->top, all the limbs of
the BIGNUM are accessed up to bn->dmax and bitwise masking is used to
avoid branching.

Memory access pattern still leaks bn->dmax, the size of the lazily
allocated buffer for representing the BIGNUM, which is inevitable with
the current BIGNUM architecture: reading past bn->dmax would be an
out-of-bound read.
As such, it's the caller responsibility to ensure that bn->dmax does not
leak secret information, by explicitly expanding the internal BIGNUM
buffer to a public value sufficient to avoid any lazy reallocation
while manipulating it: this should be already done at the top level
alongside setting the BN_FLG_CONSTTIME.

Thanks to David Schrammel and Samuel Weiser for reporting this issue
through responsible disclosure.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/9511)
2019-09-07 02:06:29 +03:00
.github Auto add a label depending on the type of issue they report. 2019-07-16 20:33:01 +02:00
apps App updates for KDF provider conversion. 2019-09-06 19:27:57 +10:00
boringssl@2070f8ad91
Configurations testing: set OPENSSL_MODULES to the providers directory by default 2019-08-27 11:53:33 +02:00
crypto Make BN_num_bits() consttime upon BN_FLG_CONSTTIME 2019-09-07 02:06:29 +03:00
demos Fix Typos 2019-07-02 14:22:29 +02:00
doc Remove reference to legacy aliases for MAC and KDF 2019-09-06 19:27:57 +10:00
engines Replace FUNCerr with ERR_raise_data 2019-08-02 11:41:54 +02:00
external/perl
fuzz Update fuzz README.md 2019-08-29 11:01:39 +01:00
include Move OSSL_OP_KDF into its rightful place amongst the other OSSL_OP_ definitions 2019-09-06 19:27:57 +10:00
krb5@b9ad6c4950
ms Windows: Call TerminateProcess, not ExitProcess 2019-02-22 21:03:45 +01:00
os-dep
providers PBKDF2 implementation: refactor to avoid memleak 2019-09-06 19:27:57 +10:00
pyca-cryptography@09403100de
ssl Fix TLS/SSL PRF usages. 2019-09-06 19:27:57 +10:00
test Lowercase command line 'N' argument since params have lower case names 2019-09-06 19:27:57 +10:00
tools
util libcrypto.num entries for KDFs 2019-09-06 19:27:58 +10:00
VMS
.gitattributes
.gitignore Refactor apps/progs.* to be generate with 'make update' 2019-07-15 07:00:29 +02:00
.gitmodules
.travis-apt-pin.preferences
.travis-create-release.sh
.travis.yml Make failed messages easier to find 2019-09-05 10:56:31 +02:00
ACKNOWLEDGEMENTS
appveyor.yml
AUTHORS
build.info Move where include path for providers/common/include gets specified 2019-05-23 11:02:04 +01:00
CHANGES Fix NITs in comments and CHANGES for DEVRANDOM seeded check. 2019-08-30 07:55:46 +10:00
config iOS build: Replace %20 with space in config script 2019-07-08 10:55:57 +02:00
config.com
Configure Configure: Allow 'DEFINE[]=def' 2019-08-23 17:16:48 +02:00
CONTRIBUTING Add a note in the contributing file about trivial commits. 2019-06-27 23:23:17 +10:00
e_os.h Don't include the DEVRANDOM being seeded logic on Android. 2019-08-30 08:01:34 +10:00
FAQ
HACKING A very brief explanation of how to add custom functions to OpenSSL. 2019-07-08 20:09:13 +10:00
INSTALL INSTALL: clarify documentation of the --api=x.y.z deprecation option 2019-08-15 14:57:18 +02:00
LICENSE
NEWS Document recent changes in NEWS and CHANGES 2019-07-31 09:33:24 +02:00
NOTES.ANDROID Remove unnecessary trailing whitespace 2019-02-05 16:25:11 +01:00
NOTES.DJGPP Remove unnecessary trailing whitespace 2019-02-05 16:25:11 +01:00
NOTES.PERL Fix typo in NOTES.PERL 2019-05-16 11:46:59 +10:00
NOTES.UNIX
NOTES.VALGRIND Add documentation for running unit tests under Valgrind 2019-05-03 17:46:28 +02:00
NOTES.VMS Remove unnecessary trailing whitespace 2019-02-05 16:25:11 +01:00
NOTES.WIN Configure: final cleanup of asm related things 2019-06-17 16:08:53 +02:00
README
README.ENGINE
README.FIPS

README 

 OpenSSL 3.0.0-dev

 Copyright (c) 1998-2018 The OpenSSL Project
 Copyright (c) 1995-1998 Eric A. Young, Tim J. Hudson
 All rights reserved.

 DESCRIPTION
 -----------

 The OpenSSL Project is a collaborative effort to develop a robust,
 commercial-grade, fully featured, and Open Source toolkit implementing the
 Transport Layer Security (TLS) protocols (including SSLv3) as well as a
 full-strength general purpose cryptographic library.

 OpenSSL is descended from the SSLeay library developed by Eric A. Young
 and Tim J. Hudson.

 The OpenSSL toolkit is licensed under the Apache License 2.0, which means
 that you are free to get and use it for commercial and non-commercial
 purposes as long as you fulfill its conditions.

 OVERVIEW
 --------

 The OpenSSL toolkit includes:

 libssl (with platform specific naming):
     Provides the client and server-side implementations for SSLv3 and TLS.

 libcrypto (with platform specific naming):
     Provides general cryptographic and X.509 support needed by SSL/TLS but
     not logically part of it.

 openssl:
     A command line tool that can be used for:
        Creation of key parameters
        Creation of X.509 certificates, CSRs and CRLs
        Calculation of message digests
        Encryption and decryption
        SSL/TLS client and server tests
        Handling of S/MIME signed or encrypted mail
        And more...

 INSTALLATION
 ------------

 See the appropriate file:
        INSTALL         Linux, Unix, Windows, OpenVMS, ...
        NOTES.*         INSTALL addendums for different platforms

 SUPPORT
 -------

 See the OpenSSL website www.openssl.org for details on how to obtain
 commercial technical support. Free community support is available through the
 openssl-users email list (see
 https://www.openssl.org/community/mailinglists.html for further details).

 If you have any problems with OpenSSL then please take the following steps
 first:

    - Download the latest version from the repository
      to see if the problem has already been addressed
    - Configure with no-asm
    - Remove compiler optimization flags

 If you wish to report a bug then please include the following information
 and create an issue on GitHub:

    - OpenSSL version: output of 'openssl version -a'
    - Configuration data: output of 'perl configdata.pm --dump'
    - OS Name, Version, Hardware platform
    - Compiler Details (name, version)
    - Application Details (name, version)
    - Problem Description (steps that will reproduce the problem, if known)
    - Stack Traceback (if the application dumps core)

 Just because something doesn't work the way you expect does not mean it
 is necessarily a bug in OpenSSL. Use the openssl-users email list for this type
 of query.

 HOW TO CONTRIBUTE TO OpenSSL
 ----------------------------

 See CONTRIBUTING

 LEGALITIES
 ----------

 A number of nations restrict the use or export of cryptography. If you
 are potentially subject to such restrictions you should seek competent
 professional legal advice before attempting to develop or distribute
 cryptographic code.