TLS/SSL and crypto library
9a43a73380
Description ----------- Upon `EC_GROUP_new_from_ecparameters()` check if the parameters match any of the built-in curves. If that is the case, return a new `EC_GROUP_new_by_curve_name()` object instead of the explicit parameters `EC_GROUP`. This affects all users of `EC_GROUP_new_from_ecparameters()`: - direct calls to `EC_GROUP_new_from_ecparameters()` - direct calls to `EC_GROUP_new_from_ecpkparameters()` with an explicit parameters argument - ASN.1 parsing of explicit parameters keys (as it eventually ends up calling `EC_GROUP_new_from_ecpkparameters()`) A parsed explicit parameter key will still be marked with the `OPENSSL_EC_EXPLICIT_CURVE` ASN.1 flag on load, so, unless programmatically forced otherwise, if the key is eventually serialized the output will still be encoded with explicit parameters, even if internally it is treated as a named curve `EC_GROUP`. Before this change, creating any `EC_GROUP` object using `EC_GROUP_new_from_ecparameters()`, yielded an object associated with the default generic `EC_METHOD`, but this was never guaranteed in the documentation. After this commit, users of the library that intentionally want to create an `EC_GROUP` object using a specific `EC_METHOD` can still explicitly call `EC_GROUP_new(foo_method)` and then manually set the curve parameters using `EC_GROUP_set_*()`. Motivation ---------- This has obvious performance benefits for the built-in curves with specialized `EC_METHOD`s and subtle but important security benefits: - the specialized methods have better security hardening than the generic implementations - optional fields in the parameter encoding, like the `cofactor`, cannot be leveraged by an attacker to force execution of the less secure code-paths for single point scalar multiplication - in general, this leads to reducing the attack surface Check the manuscript at https://arxiv.org/abs/1909.01785 for an in depth analysis of the issues related to this commit. It should be noted that `libssl` does not allow to negotiate explicit parameters (as per RFC 8422), so it is not directly affected by the consequences of using explicit parameters that this commit fixes. On the other hand, we detected external applications and users in the wild that use explicit parameters by default (and sometimes using 0 as the cofactor value, which is technically not a valid value per the specification, but is tolerated by parsers for wider compatibility given that the field is optional). These external users of `libcrypto` are exposed to these vulnerabilities and their security will benefit from this commit. Related commits --------------- While this commit is beneficial for users using built-in curves and explicit parameters encoding for serialized keys, commit b783beeadf6b80bc431e6f3230b5d5585c87ef87 (and its equivalents for the 1.0.2, 1.1.0 and 1.1.1 stable branches) fixes the consequences of the invalid cofactor values more in general also for other curves (CVE-2019-1547). The following list covers commits in `master` that are related to the vulnerabilities presented in the manuscript motivating this commit: - d2baf88c43 [crypto/rsa] Set the constant-time flag in multi-prime RSA too - 311e903d84 [crypto/asn1] Fix multiple SCA vulnerabilities during RSA key validation. - b783beeadf [crypto/ec] for ECC parameters with NULL or zero cofactor, compute it - |
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OpenSSL 1.1.1d-dev
Copyright (c) 1998-2019 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 a dual-license (the
OpenSSL license plus the SSLeay license), which means that you are free to
get and use it for commercial and non-commercial purposes as long as you
fulfill the conditions of both licenses.
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.