|
 |
fd2893 |
Guide for legacy support enablement
|
|
|
fd2893 |
===================================
|
|
|
fd2893 |
|
|
|
fd2893 |
To improve security provided by use of OpenSSL especially in context of
|
|
|
fd2893 |
TLS connections we regularly review and deprecate algorithms and algorithm
|
|
|
fd2893 |
settings which are no longer viewed as secure.
|
|
|
fd2893 |
|
|
|
fd2893 |
For some of these deprecated algorithms we provide a way for the
|
|
|
fd2893 |
system administrator to reenable them.
|
|
|
fd2893 |
|
|
|
fd2893 |
Deprecated algorithms, protocols and settings in OpenSSL
|
|
|
fd2893 |
========================================================
|
|
|
fd2893 |
|
|
|
fd2893 |
Previous Red Hat Enterprise Linux 7 update releases:
|
|
|
fd2893 |
|
|
|
fd2893 |
* SSL2 protocol disabled by default.
|
|
|
fd2893 |
* Minimum DH group size accepted by SSL/TLS client 768 bits.
|
|
|
fd2893 |
* Verification of certificates and signatures using MD5 hash
|
|
|
fd2893 |
disabled.
|
|
|
fd2893 |
|
|
|
fd2893 |
Red Hat Enterprise Linux 7.4:
|
|
|
fd2893 |
|
|
|
fd2893 |
* SSL2 protocol support completely disabled (cannot be re-enabled).
|
|
|
fd2893 |
* All SSL/TLS export ciphers disabled.
|
|
|
fd2893 |
* All SSL/TLS ciphersuites with keys smaller than 128 bits disabled.
|
|
|
fd2893 |
* Minimum DH group size accepted by SSL/TLS client 1024 bits.
|
|
|
fd2893 |
* Disabled support for verification of certificates and signatures
|
|
|
fd2893 |
using MD2, MD4, MD5, and SHA0 hashes.
|
|
|
fd2893 |
|
|
|
fd2893 |
Legacy support enablement
|
|
|
fd2893 |
=========================
|
|
|
fd2893 |
|
|
|
fd2893 |
The OpenSSL now supports /etc/pki/tls/legacy-settings configuration file
|
|
|
fd2893 |
which can be created by the system administrator which contains lines with
|
|
|
fd2893 |
simple Key Value pairs.
|
|
|
fd2893 |
|
|
|
fd2893 |
The library recognizes the following possible configuration settings in
|
|
|
fd2893 |
that file:
|
|
|
fd2893 |
|
|
|
fd2893 |
LegacySigningMDs md2 md5
|
|
|
fd2893 |
MinimumDHBits 512
|
|
|
fd2893 |
|
|
|
fd2893 |
The LegacySigningMDs option allows reenabling support for verification of
|
|
|
fd2893 |
signatures with the specified hash algorithms. These can be any combination
|
|
|
fd2893 |
of md2, md4, md5 and sha. (sha represents SHA0 algorithm, not SHA1.) Any
|
|
|
fd2893 |
unrecognized algorithms are ignored.
|
|
|
fd2893 |
|
|
|
fd2893 |
The MinimumDHBits option allows setting of the minimum bit size of DH group
|
|
|
fd2893 |
accepted by SSL/TLS client. It can be any value between 512 and 10000.
|
|
|
fd2893 |
|
|
|
fd2893 |
If the configuration file is not present the built-in defaults (that is the
|
|
|
fd2893 |
secure defaults) are used. Any unrecognized lines (with other parameter
|
|
|
fd2893 |
names or comments) are ignored.
|