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author | William Joye <wjoye@cfa.harvard.edu> | 2017-05-02 16:40:01 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2017-05-02 16:40:01 (GMT) |
commit | 0a2b8b8e0bc2e91a9f10659b30e2e4f5b79ce692 (patch) | |
tree | 3d0871d05cfd11f60b86829d2d93704034dad24e /openssl/README.ENGINE | |
parent | e9abe0dba896d2b0fc22301588336e89ff246ba7 (diff) | |
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reinstall
Diffstat (limited to 'openssl/README.ENGINE')
-rw-r--r-- | openssl/README.ENGINE | 289 |
1 files changed, 0 insertions, 289 deletions
diff --git a/openssl/README.ENGINE b/openssl/README.ENGINE deleted file mode 100644 index 0ff8333..0000000 --- a/openssl/README.ENGINE +++ /dev/null @@ -1,289 +0,0 @@ - ENGINE - ====== - - 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. - - There are currently built-in ENGINE implementations for the following - crypto devices: - - o CryptoSwift - o Compaq Atalla - o nCipher CHIL - o Nuron - o Broadcom uBSec - - In addition, dynamic binding to external ENGINE implementations is now - provided by a special ENGINE called "dynamic". See the "DYNAMIC ENGINE" - section below for details. - - At this stage, a number of things are still needed and are being worked on: - - 1 Integration of EVP support. - 2 Configuration support. - 3 Documentation! - -1 With respect to EVP, this relates to support for ciphers and digests in - the ENGINE model so that alternative implementations of existing - algorithms/modes (or previously unimplemented ones) can be provided by - ENGINE implementations. - -2 Configuration support currently exists in the ENGINE API itself, in the - form of "control commands". These allow an application to expose to the - user/admin the set of commands and parameter types a given ENGINE - implementation supports, and for an application to directly feed string - based input to those ENGINEs, in the form of name-value pairs. This is an - extensible way for ENGINEs to define their own "configuration" mechanisms - that are specific to a given ENGINE (eg. for a particular hardware - device) but that should be consistent across *all* OpenSSL-based - applications when they use that ENGINE. Work is in progress (or at least - in planning) for supporting these control commands from the CONF (or - NCONF) code so that applications using OpenSSL's existing configuration - file format can have ENGINE settings specified in much the same way. - Presently however, applications must use the ENGINE API itself to provide - such functionality. To see first hand the types of commands available - with the various compiled-in ENGINEs (see further down for dynamic - ENGINEs), use the "engine" openssl utility with full verbosity, ie; - openssl engine -vvvv - -3 Documentation? Volunteers welcome! The source code is reasonably well - self-documenting, but some summaries and usage instructions are needed - - moreover, they are needed in the same POD format the existing OpenSSL - documentation is provided in. Any complete or incomplete contributions - would help make this happen. - - STABILITY & BUG-REPORTS - ======================= - - What already exists is fairly stable as far as it has been tested, but - the test base has been a bit small most of the time. For the most part, - the vendors of the devices these ENGINEs support have contributed to the - development and/or testing of the implementations, and *usually* (with no - guarantees) have experience in using the ENGINE support to drive their - devices from common OpenSSL-based applications. Bugs and/or inexplicable - behaviour in using a specific ENGINE implementation should be sent to the - author of that implementation (if it is mentioned in the corresponding C - file), and in the case of implementations for commercial hardware - devices, also through whatever vendor support channels are available. If - none of this is possible, or the problem seems to be something about the - ENGINE API itself (ie. not necessarily specific to a particular ENGINE - implementation) then you should mail complete details to the relevant - OpenSSL mailing list. For a definition of "complete details", refer to - the OpenSSL "README" file. As for which list to send it to; - - openssl-users: if you are *using* the ENGINE abstraction, either in an - pre-compiled application or in your own application code. - - openssl-dev: if you are discussing problems with OpenSSL source code. - - USAGE - ===== - - The default "openssl" ENGINE is always chosen when performing crypto - operations unless you specify otherwise. You must actively tell the - openssl utility commands to use anything else through a new command line - switch called "-engine". Also, if you want to use the ENGINE support in - your own code to do something similar, you must likewise explicitly - select the ENGINE implementation you want. - - Depending on the type of hardware, system, and configuration, "settings" - may need to be applied to an ENGINE for it to function as expected/hoped. - The recommended way of doing this is for the application to support - ENGINE "control commands" so that each ENGINE implementation can provide - whatever configuration primitives it might require and the application - can allow the user/admin (and thus the hardware vendor's support desk - also) to provide any such input directly to the ENGINE implementation. - This way, applications do not need to know anything specific to any - device, they only need to provide the means to carry such user/admin - input through to the ENGINE in question. Ie. this connects *you* (and - your helpdesk) to the specific ENGINE implementation (and device), and - allows application authors to not get buried in hassle supporting - arbitrary devices they know (and care) nothing about. - - A new "openssl" utility, "openssl engine", has been added in that allows - for testing and examination of ENGINE implementations. Basic usage - instructions are available by specifying the "-?" command line switch. - - DYNAMIC ENGINES - =============== - - The new "dynamic" ENGINE provides a low-overhead way to support ENGINE - implementations that aren't pre-compiled and linked into OpenSSL-based - applications. This could be because existing compiled-in implementations - have known problems and you wish to use a newer version with an existing - application. It could equally be because the application (or OpenSSL - library) you are using simply doesn't have support for the ENGINE you - wish to use, and the ENGINE provider (eg. hardware vendor) is providing - you with a self-contained implementation in the form of a shared-library. - The other use-case for "dynamic" is with applications that wish to - maintain the smallest foot-print possible and so do not link in various - ENGINE implementations from OpenSSL, but instead leaves you to provide - them, if you want them, in the form of "dynamic"-loadable - shared-libraries. It should be possible for hardware vendors to provide - their own shared-libraries to support arbitrary hardware to work with - applications based on OpenSSL 0.9.7 or later. If you're using an - application based on 0.9.7 (or later) and the support you desire is only - announced for versions later than the one you need, ask the vendor to - backport their ENGINE to the version you need. - - How does "dynamic" work? - ------------------------ - The dynamic ENGINE has a special flag in its implementation such that - every time application code asks for the 'dynamic' ENGINE, it in fact - gets its own copy of it. As such, multi-threaded code (or code that - multiplexes multiple uses of 'dynamic' in a single application in any - way at all) does not get confused by 'dynamic' being used to do many - independent things. Other ENGINEs typically don't do this so there is - only ever 1 ENGINE structure of its type (and reference counts are used - to keep order). The dynamic ENGINE itself provides absolutely no - cryptographic functionality, and any attempt to "initialise" the ENGINE - automatically fails. All it does provide are a few "control commands" - that can be used to control how it will load an external ENGINE - implementation from a shared-library. To see these control commands, - use the command-line; - - openssl engine -vvvv dynamic - - The "SO_PATH" control command should be used to identify the - shared-library that contains the ENGINE implementation, and "NO_VCHECK" - might possibly be useful if there is a minor version conflict and you - (or a vendor helpdesk) is convinced you can safely ignore it. - "ID" is probably only needed if a shared-library implements - multiple ENGINEs, but if you know the engine id you expect to be using, - it doesn't hurt to specify it (and this provides a sanity check if - nothing else). "LIST_ADD" is only required if you actually wish the - loaded ENGINE to be discoverable by application code later on using the - ENGINE's "id". For most applications, this isn't necessary - but some - application authors may have nifty reasons for using it. The "LOAD" - command is the only one that takes no parameters and is the command - that uses the settings from any previous commands to actually *load* - the shared-library ENGINE implementation. If this command succeeds, the - (copy of the) 'dynamic' ENGINE will magically morph into the ENGINE - that has been loaded from the shared-library. As such, any control - commands supported by the loaded ENGINE could then be executed as per - normal. Eg. if ENGINE "foo" is implemented in the shared-library - "libfoo.so" and it supports some special control command "CMD_FOO", the - following code would load and use it (NB: obviously this code has no - error checking); - - ENGINE *e = ENGINE_by_id("dynamic"); - ENGINE_ctrl_cmd_string(e, "SO_PATH", "/lib/libfoo.so", 0); - ENGINE_ctrl_cmd_string(e, "ID", "foo", 0); - ENGINE_ctrl_cmd_string(e, "LOAD", NULL, 0); - ENGINE_ctrl_cmd_string(e, "CMD_FOO", "some input data", 0); - - For testing, the "openssl engine" utility can be useful for this sort - of thing. For example the above code excerpt would achieve much the - same result as; - - openssl engine dynamic \ - -pre SO_PATH:/lib/libfoo.so \ - -pre ID:foo \ - -pre LOAD \ - -pre "CMD_FOO:some input data" - - Or to simply see the list of commands supported by the "foo" ENGINE; - - openssl engine -vvvv dynamic \ - -pre SO_PATH:/lib/libfoo.so \ - -pre ID:foo \ - -pre LOAD - - Applications that support the ENGINE API and more specifically, the - "control commands" mechanism, will provide some way for you to pass - such commands through to ENGINEs. As such, you would select "dynamic" - as the ENGINE to use, and the parameters/commands you pass would - control the *actual* ENGINE used. Each command is actually a name-value - pair and the value can sometimes be omitted (eg. the "LOAD" command). - Whilst the syntax demonstrated in "openssl engine" uses a colon to - separate the command name from the value, applications may provide - their own syntax for making that separation (eg. a win32 registry - key-value pair may be used by some applications). The reason for the - "-pre" syntax in the "openssl engine" utility is that some commands - might be issued to an ENGINE *after* it has been initialised for use. - Eg. if an ENGINE implementation requires a smart-card to be inserted - during initialisation (or a PIN to be typed, or whatever), there may be - a control command you can issue afterwards to "forget" the smart-card - so that additional initialisation is no longer possible. In - applications such as web-servers, where potentially volatile code may - run on the same host system, this may provide some arguable security - value. In such a case, the command would be passed to the ENGINE after - it has been initialised for use, and so the "-post" switch would be - used instead. Applications may provide a different syntax for - supporting this distinction, and some may simply not provide it at all - ("-pre" is almost always what you're after, in reality). - - How do I build a "dynamic" ENGINE? - ---------------------------------- - This question is trickier - currently OpenSSL bundles various ENGINE - implementations that are statically built in, and any application that - calls the "ENGINE_load_builtin_engines()" function will automatically - have all such ENGINEs available (and occupying memory). Applications - that don't call that function have no ENGINEs available like that and - would have to use "dynamic" to load any such ENGINE - but on the other - hand such applications would only have the memory footprint of any - ENGINEs explicitly loaded using user/admin provided control commands. - The main advantage of not statically linking ENGINEs and only using - "dynamic" for hardware support is that any installation using no - "external" ENGINE suffers no unnecessary memory footprint from unused - ENGINEs. Likewise, installations that do require an ENGINE incur the - overheads from only *that* ENGINE once it has been loaded. - - Sounds good? Maybe, but currently building an ENGINE implementation as - a shared-library that can be loaded by "dynamic" isn't automated in - OpenSSL's build process. It can be done manually quite easily however. - Such a shared-library can either be built with any OpenSSL code it - needs statically linked in, or it can link dynamically against OpenSSL - if OpenSSL itself is built as a shared library. The instructions are - the same in each case, but in the former (statically linked any - dependencies on OpenSSL) you must ensure OpenSSL is built with - position-independent code ("PIC"). The default OpenSSL compilation may - already specify the relevant flags to do this, but you should consult - with your compiler documentation if you are in any doubt. - - This example will show building the "atalla" ENGINE in the - crypto/engine/ directory as a shared-library for use via the "dynamic" - ENGINE. - 1) "cd" to the crypto/engine/ directory of a pre-compiled OpenSSL - source tree. - 2) Recompile at least one source file so you can see all the compiler - flags (and syntax) being used to build normally. Eg; - touch hw_atalla.c ; make - will rebuild "hw_atalla.o" using all such flags. - 3) Manually enter the same compilation line to compile the - "hw_atalla.c" file but with the following two changes; - (a) add "-DENGINE_DYNAMIC_SUPPORT" to the command line switches, - (b) change the output file from "hw_atalla.o" to something new, - eg. "tmp_atalla.o" - 4) Link "tmp_atalla.o" into a shared-library using the top-level - OpenSSL libraries to resolve any dependencies. The syntax for doing - this depends heavily on your system/compiler and is a nightmare - known well to anyone who has worked with shared-library portability - before. 'gcc' on Linux, for example, would use the following syntax; - gcc -shared -o dyn_atalla.so tmp_atalla.o -L../.. -lcrypto - 5) Test your shared library using "openssl engine" as explained in the - previous section. Eg. from the top-level directory, you might try; - apps/openssl engine -vvvv dynamic \ - -pre SO_PATH:./crypto/engine/dyn_atalla.so -pre LOAD - If the shared-library loads successfully, you will see both "-pre" - commands marked as "SUCCESS" and the list of control commands - displayed (because of "-vvvv") will be the control commands for the - *atalla* ENGINE (ie. *not* the 'dynamic' ENGINE). You can also add - the "-t" switch to the utility if you want it to try and initialise - the atalla ENGINE for use to test any possible hardware/driver - issues. - - PROBLEMS - ======== - - It seems like the ENGINE part doesn't work too well with CryptoSwift on Win32. - A quick test done right before the release showed that trying "openssl speed - -engine cswift" generated errors. If the DSO gets enabled, an attempt is made - to write at memory address 0x00000002. - |