Add deprecation note to the README-ENGINES file

Reviewed-by: Paul Dale <>
(Merged from
Dr. Matthias St. Pierre 2 years ago
parent 4148581eb2
commit d507436a26

@ -1,14 +1,23 @@
With OpenSSL 0.9.6, a new component was added to support alternative
cryptography implementations, most commonly for interfacing with external
crypto devices (eg. accelerator cards). This component is called ENGINE,
and its presence in OpenSSL 0.9.6 (and subsequent bug-fix releases)
caused a little confusion as 0.9.6** releases were rolled in two
versions, a "standard" and an "engine" version. In development for 0.9.7,
the ENGINE code has been merged into the main branch and will be present
in the standard releases from 0.9.7 forwards.
Deprecation Note
The ENGINE API was introduced in OpenSSL version 0.9.6 as a low level
interface for adding alternative implementations of cryptographic
primitives, most notably for integrating hardware crypto devices.
The ENGINE interface has its limitations and it has been superseeded
by the [PROVIDER API](, it is deprecated in OpenSSL
version 3.0. The following documentation is retained as an aid for
users who need to maintain or support existing ENGINE implementations.
Support for new hardware devices or new algorithms should be added
via providers, and existing engines should be converted to providers
as soon as possible.
Built-in ENGINE implementations
There are currently built-in ENGINE implementations for the following
crypto devices: