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diff --git a/secure/lib/libcrypto/man/engine.3 b/secure/lib/libcrypto/man/engine.3 new file mode 100644 index 0000000..3c22397 --- /dev/null +++ b/secure/lib/libcrypto/man/engine.3 @@ -0,0 +1,737 @@ +.\" Automatically generated by Pod::Man 2.22 (Pod::Simple 3.07) +.\" +.\" Standard preamble: +.\" ======================================================================== +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.de Vb \" Begin verbatim text +.ft CW +.nf +.ne \\$1 +.. +.de Ve \" End verbatim text +.ft R +.fi +.. +.\" Set up some character translations and predefined strings. \*(-- will +.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left +.\" double quote, and \*(R" will give a right double quote. \*(C+ will +.\" give a nicer C++. Capital omega is used to do unbreakable dashes and +.\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff, +.\" nothing in troff, for use with C<>. +.tr \(*W- +.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' +.ie n \{\ +. ds -- \(*W- +. ds PI pi +. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch +. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch +. ds L" "" +. ds R" "" +. ds C` "" +. ds C' "" +'br\} +.el\{\ +. ds -- \|\(em\| +. ds PI \(*p +. ds L" `` +. ds R" '' +'br\} +.\" +.\" Escape single quotes in literal strings from groff's Unicode transform. +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" +.\" If the F register is turned on, we'll generate index entries on stderr for +.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index +.\" entries marked with X<> in POD. Of course, you'll have to process the +.\" output yourself in some meaningful fashion. +.ie \nF \{\ +. de IX +. tm Index:\\$1\t\\n%\t"\\$2" +.. +. nr % 0 +. rr F +.\} +.el \{\ +. de IX +.. +.\} +.\" +.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). +.\" Fear. Run. Save yourself. No user-serviceable parts. +. \" fudge factors for nroff and troff +.if n \{\ +. ds #H 0 +. ds #V .8m +. ds #F .3m +. ds #[ \f1 +. ds #] \fP +.\} +.if t \{\ +. ds #H ((1u-(\\\\n(.fu%2u))*.13m) +. ds #V .6m +. ds #F 0 +. ds #[ \& +. ds #] \& +.\} +. \" simple accents for nroff and troff +.if n \{\ +. ds ' \& +. ds ` \& +. ds ^ \& +. ds , \& +. ds ~ ~ +. ds / +.\} +.if t \{\ +. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" +. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' +. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' +. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' +. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' +. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' +.\} +. \" troff and (daisy-wheel) nroff accents +.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' +.ds 8 \h'\*(#H'\(*b\h'-\*(#H' +.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] +.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' +.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' +.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] +.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] +.ds ae a\h'-(\w'a'u*4/10)'e +.ds Ae A\h'-(\w'A'u*4/10)'E +. \" corrections for vroff +.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' +.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' +. \" for low resolution devices (crt and lpr) +.if \n(.H>23 .if \n(.V>19 \ +\{\ +. ds : e +. ds 8 ss +. ds o a +. ds d- d\h'-1'\(ga +. ds D- D\h'-1'\(hy +. ds th \o'bp' +. ds Th \o'LP' +. ds ae ae +. ds Ae AE +.\} +.rm #[ #] #H #V #F C +.\" ======================================================================== +.\" +.IX Title "engine 3" +.TH engine 3 "2010-11-16" "0.9.8p" "OpenSSL" +.\" For nroff, turn off justification. Always turn off hyphenation; it makes +.\" way too many mistakes in technical documents. +.if n .ad l +.nh +.SH "NAME" +engine \- ENGINE cryptographic module support +.SH "SYNOPSIS" +.IX Header "SYNOPSIS" +.Vb 1 +\& #include <openssl/engine.h> +\& +\& ENGINE *ENGINE_get_first(void); +\& ENGINE *ENGINE_get_last(void); +\& ENGINE *ENGINE_get_next(ENGINE *e); +\& ENGINE *ENGINE_get_prev(ENGINE *e); +\& +\& int ENGINE_add(ENGINE *e); +\& int ENGINE_remove(ENGINE *e); +\& +\& ENGINE *ENGINE_by_id(const char *id); +\& +\& int ENGINE_init(ENGINE *e); +\& int ENGINE_finish(ENGINE *e); +\& +\& void ENGINE_load_openssl(void); +\& void ENGINE_load_dynamic(void); +\& #ifndef OPENSSL_NO_STATIC_ENGINE +\& void ENGINE_load_4758cca(void); +\& void ENGINE_load_aep(void); +\& void ENGINE_load_atalla(void); +\& void ENGINE_load_chil(void); +\& void ENGINE_load_cswift(void); +\& void ENGINE_load_gmp(void); +\& void ENGINE_load_nuron(void); +\& void ENGINE_load_sureware(void); +\& void ENGINE_load_ubsec(void); +\& #endif +\& void ENGINE_load_cryptodev(void); +\& void ENGINE_load_builtin_engines(void); +\& +\& void ENGINE_cleanup(void); +\& +\& ENGINE *ENGINE_get_default_RSA(void); +\& ENGINE *ENGINE_get_default_DSA(void); +\& ENGINE *ENGINE_get_default_ECDH(void); +\& ENGINE *ENGINE_get_default_ECDSA(void); +\& ENGINE *ENGINE_get_default_DH(void); +\& ENGINE *ENGINE_get_default_RAND(void); +\& ENGINE *ENGINE_get_cipher_engine(int nid); +\& ENGINE *ENGINE_get_digest_engine(int nid); +\& +\& int ENGINE_set_default_RSA(ENGINE *e); +\& int ENGINE_set_default_DSA(ENGINE *e); +\& int ENGINE_set_default_ECDH(ENGINE *e); +\& int ENGINE_set_default_ECDSA(ENGINE *e); +\& int ENGINE_set_default_DH(ENGINE *e); +\& int ENGINE_set_default_RAND(ENGINE *e); +\& int ENGINE_set_default_ciphers(ENGINE *e); +\& int ENGINE_set_default_digests(ENGINE *e); +\& int ENGINE_set_default_string(ENGINE *e, const char *list); +\& +\& int ENGINE_set_default(ENGINE *e, unsigned int flags); +\& +\& unsigned int ENGINE_get_table_flags(void); +\& void ENGINE_set_table_flags(unsigned int flags); +\& +\& int ENGINE_register_RSA(ENGINE *e); +\& void ENGINE_unregister_RSA(ENGINE *e); +\& void ENGINE_register_all_RSA(void); +\& int ENGINE_register_DSA(ENGINE *e); +\& void ENGINE_unregister_DSA(ENGINE *e); +\& void ENGINE_register_all_DSA(void); +\& int ENGINE_register_ECDH(ENGINE *e); +\& void ENGINE_unregister_ECDH(ENGINE *e); +\& void ENGINE_register_all_ECDH(void); +\& int ENGINE_register_ECDSA(ENGINE *e); +\& void ENGINE_unregister_ECDSA(ENGINE *e); +\& void ENGINE_register_all_ECDSA(void); +\& int ENGINE_register_DH(ENGINE *e); +\& void ENGINE_unregister_DH(ENGINE *e); +\& void ENGINE_register_all_DH(void); +\& int ENGINE_register_RAND(ENGINE *e); +\& void ENGINE_unregister_RAND(ENGINE *e); +\& void ENGINE_register_all_RAND(void); +\& int ENGINE_register_STORE(ENGINE *e); +\& void ENGINE_unregister_STORE(ENGINE *e); +\& void ENGINE_register_all_STORE(void); +\& int ENGINE_register_ciphers(ENGINE *e); +\& void ENGINE_unregister_ciphers(ENGINE *e); +\& void ENGINE_register_all_ciphers(void); +\& int ENGINE_register_digests(ENGINE *e); +\& void ENGINE_unregister_digests(ENGINE *e); +\& void ENGINE_register_all_digests(void); +\& int ENGINE_register_complete(ENGINE *e); +\& int ENGINE_register_all_complete(void); +\& +\& int ENGINE_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void)); +\& int ENGINE_cmd_is_executable(ENGINE *e, int cmd); +\& int ENGINE_ctrl_cmd(ENGINE *e, const char *cmd_name, +\& long i, void *p, void (*f)(void), int cmd_optional); +\& int ENGINE_ctrl_cmd_string(ENGINE *e, const char *cmd_name, const char *arg, +\& int cmd_optional); +\& +\& int ENGINE_set_ex_data(ENGINE *e, int idx, void *arg); +\& void *ENGINE_get_ex_data(const ENGINE *e, int idx); +\& +\& int ENGINE_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func, +\& CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func); +\& +\& ENGINE *ENGINE_new(void); +\& int ENGINE_free(ENGINE *e); +\& int ENGINE_up_ref(ENGINE *e); +\& +\& int ENGINE_set_id(ENGINE *e, const char *id); +\& int ENGINE_set_name(ENGINE *e, const char *name); +\& int ENGINE_set_RSA(ENGINE *e, const RSA_METHOD *rsa_meth); +\& int ENGINE_set_DSA(ENGINE *e, const DSA_METHOD *dsa_meth); +\& int ENGINE_set_ECDH(ENGINE *e, const ECDH_METHOD *dh_meth); +\& int ENGINE_set_ECDSA(ENGINE *e, const ECDSA_METHOD *dh_meth); +\& int ENGINE_set_DH(ENGINE *e, const DH_METHOD *dh_meth); +\& int ENGINE_set_RAND(ENGINE *e, const RAND_METHOD *rand_meth); +\& int ENGINE_set_STORE(ENGINE *e, const STORE_METHOD *rand_meth); +\& int ENGINE_set_destroy_function(ENGINE *e, ENGINE_GEN_INT_FUNC_PTR destroy_f); +\& int ENGINE_set_init_function(ENGINE *e, ENGINE_GEN_INT_FUNC_PTR init_f); +\& int ENGINE_set_finish_function(ENGINE *e, ENGINE_GEN_INT_FUNC_PTR finish_f); +\& int ENGINE_set_ctrl_function(ENGINE *e, ENGINE_CTRL_FUNC_PTR ctrl_f); +\& int ENGINE_set_load_privkey_function(ENGINE *e, ENGINE_LOAD_KEY_PTR loadpriv_f); +\& int ENGINE_set_load_pubkey_function(ENGINE *e, ENGINE_LOAD_KEY_PTR loadpub_f); +\& int ENGINE_set_ciphers(ENGINE *e, ENGINE_CIPHERS_PTR f); +\& int ENGINE_set_digests(ENGINE *e, ENGINE_DIGESTS_PTR f); +\& int ENGINE_set_flags(ENGINE *e, int flags); +\& int ENGINE_set_cmd_defns(ENGINE *e, const ENGINE_CMD_DEFN *defns); +\& +\& const char *ENGINE_get_id(const ENGINE *e); +\& const char *ENGINE_get_name(const ENGINE *e); +\& const RSA_METHOD *ENGINE_get_RSA(const ENGINE *e); +\& const DSA_METHOD *ENGINE_get_DSA(const ENGINE *e); +\& const ECDH_METHOD *ENGINE_get_ECDH(const ENGINE *e); +\& const ECDSA_METHOD *ENGINE_get_ECDSA(const ENGINE *e); +\& const DH_METHOD *ENGINE_get_DH(const ENGINE *e); +\& const RAND_METHOD *ENGINE_get_RAND(const ENGINE *e); +\& const STORE_METHOD *ENGINE_get_STORE(const ENGINE *e); +\& ENGINE_GEN_INT_FUNC_PTR ENGINE_get_destroy_function(const ENGINE *e); +\& ENGINE_GEN_INT_FUNC_PTR ENGINE_get_init_function(const ENGINE *e); +\& ENGINE_GEN_INT_FUNC_PTR ENGINE_get_finish_function(const ENGINE *e); +\& ENGINE_CTRL_FUNC_PTR ENGINE_get_ctrl_function(const ENGINE *e); +\& ENGINE_LOAD_KEY_PTR ENGINE_get_load_privkey_function(const ENGINE *e); +\& ENGINE_LOAD_KEY_PTR ENGINE_get_load_pubkey_function(const ENGINE *e); +\& ENGINE_CIPHERS_PTR ENGINE_get_ciphers(const ENGINE *e); +\& ENGINE_DIGESTS_PTR ENGINE_get_digests(const ENGINE *e); +\& const EVP_CIPHER *ENGINE_get_cipher(ENGINE *e, int nid); +\& const EVP_MD *ENGINE_get_digest(ENGINE *e, int nid); +\& int ENGINE_get_flags(const ENGINE *e); +\& const ENGINE_CMD_DEFN *ENGINE_get_cmd_defns(const ENGINE *e); +\& +\& EVP_PKEY *ENGINE_load_private_key(ENGINE *e, const char *key_id, +\& UI_METHOD *ui_method, void *callback_data); +\& EVP_PKEY *ENGINE_load_public_key(ENGINE *e, const char *key_id, +\& UI_METHOD *ui_method, void *callback_data); +\& +\& void ENGINE_add_conf_module(void); +.Ve +.SH "DESCRIPTION" +.IX Header "DESCRIPTION" +These functions create, manipulate, and use cryptographic modules in the +form of \fB\s-1ENGINE\s0\fR objects. These objects act as containers for +implementations of cryptographic algorithms, and support a +reference-counted mechanism to allow them to be dynamically loaded in and +out of the running application. +.PP +The cryptographic functionality that can be provided by an \fB\s-1ENGINE\s0\fR +implementation includes the following abstractions; +.PP +.Vb 6 +\& RSA_METHOD \- for providing alternative RSA implementations +\& DSA_METHOD, DH_METHOD, RAND_METHOD, ECDH_METHOD, ECDSA_METHOD, +\& STORE_METHOD \- similarly for other OpenSSL APIs +\& EVP_CIPHER \- potentially multiple cipher algorithms (indexed by \*(Aqnid\*(Aq) +\& EVP_DIGEST \- potentially multiple hash algorithms (indexed by \*(Aqnid\*(Aq) +\& key\-loading \- loading public and/or private EVP_PKEY keys +.Ve +.SS "Reference counting and handles" +.IX Subsection "Reference counting and handles" +Due to the modular nature of the \s-1ENGINE\s0 \s-1API\s0, pointers to ENGINEs need to be +treated as handles \- ie. not only as pointers, but also as references to +the underlying \s-1ENGINE\s0 object. Ie. one should obtain a new reference when +making copies of an \s-1ENGINE\s0 pointer if the copies will be used (and +released) independently. +.PP +\&\s-1ENGINE\s0 objects have two levels of reference-counting to match the way in +which the objects are used. At the most basic level, each \s-1ENGINE\s0 pointer is +inherently a \fBstructural\fR reference \- a structural reference is required +to use the pointer value at all, as this kind of reference is a guarantee +that the structure can not be deallocated until the reference is released. +.PP +However, a structural reference provides no guarantee that the \s-1ENGINE\s0 is +initiliased and able to use any of its cryptographic +implementations. Indeed it's quite possible that most ENGINEs will not +initialise at all in typical environments, as ENGINEs are typically used to +support specialised hardware. To use an \s-1ENGINE\s0's functionality, you need a +\&\fBfunctional\fR reference. This kind of reference can be considered a +specialised form of structural reference, because each functional reference +implicitly contains a structural reference as well \- however to avoid +difficult-to-find programming bugs, it is recommended to treat the two +kinds of reference independently. If you have a functional reference to an +\&\s-1ENGINE\s0, you have a guarantee that the \s-1ENGINE\s0 has been initialised ready to +perform cryptographic operations and will remain uninitialised +until after you have released your reference. +.PP +\&\fIStructural references\fR +.PP +This basic type of reference is used for instantiating new ENGINEs, +iterating across OpenSSL's internal linked-list of loaded +ENGINEs, reading information about an \s-1ENGINE\s0, etc. Essentially a structural +reference is sufficient if you only need to query or manipulate the data of +an \s-1ENGINE\s0 implementation rather than use its functionality. +.PP +The \fIENGINE_new()\fR function returns a structural reference to a new (empty) +\&\s-1ENGINE\s0 object. There are other \s-1ENGINE\s0 \s-1API\s0 functions that return structural +references such as; \fIENGINE_by_id()\fR, \fIENGINE_get_first()\fR, \fIENGINE_get_last()\fR, +\&\fIENGINE_get_next()\fR, \fIENGINE_get_prev()\fR. All structural references should be +released by a corresponding to call to the \fIENGINE_free()\fR function \- the +\&\s-1ENGINE\s0 object itself will only actually be cleaned up and deallocated when +the last structural reference is released. +.PP +It should also be noted that many \s-1ENGINE\s0 \s-1API\s0 function calls that accept a +structural reference will internally obtain another reference \- typically +this happens whenever the supplied \s-1ENGINE\s0 will be needed by OpenSSL after +the function has returned. Eg. the function to add a new \s-1ENGINE\s0 to +OpenSSL's internal list is \fIENGINE_add()\fR \- if this function returns success, +then OpenSSL will have stored a new structural reference internally so the +caller is still responsible for freeing their own reference with +\&\fIENGINE_free()\fR when they are finished with it. In a similar way, some +functions will automatically release the structural reference passed to it +if part of the function's job is to do so. Eg. the \fIENGINE_get_next()\fR and +\&\fIENGINE_get_prev()\fR functions are used for iterating across the internal +\&\s-1ENGINE\s0 list \- they will return a new structural reference to the next (or +previous) \s-1ENGINE\s0 in the list or \s-1NULL\s0 if at the end (or beginning) of the +list, but in either case the structural reference passed to the function is +released on behalf of the caller. +.PP +To clarify a particular function's handling of references, one should +always consult that function's documentation \*(L"man\*(R" page, or failing that +the openssl/engine.h header file includes some hints. +.PP +\&\fIFunctional references\fR +.PP +As mentioned, functional references exist when the cryptographic +functionality of an \s-1ENGINE\s0 is required to be available. A functional +reference can be obtained in one of two ways; from an existing structural +reference to the required \s-1ENGINE\s0, or by asking OpenSSL for the default +operational \s-1ENGINE\s0 for a given cryptographic purpose. +.PP +To obtain a functional reference from an existing structural reference, +call the \fIENGINE_init()\fR function. This returns zero if the \s-1ENGINE\s0 was not +already operational and couldn't be successfully initialised (eg. lack of +system drivers, no special hardware attached, etc), otherwise it will +return non-zero to indicate that the \s-1ENGINE\s0 is now operational and will +have allocated a new \fBfunctional\fR reference to the \s-1ENGINE\s0. All functional +references are released by calling \fIENGINE_finish()\fR (which removes the +implicit structural reference as well). +.PP +The second way to get a functional reference is by asking OpenSSL for a +default implementation for a given task, eg. by \fIENGINE_get_default_RSA()\fR, +\&\fIENGINE_get_default_cipher_engine()\fR, etc. These are discussed in the next +section, though they are not usually required by application programmers as +they are used automatically when creating and using the relevant +algorithm-specific types in OpenSSL, such as \s-1RSA\s0, \s-1DSA\s0, \s-1EVP_CIPHER_CTX\s0, etc. +.SS "Default implementations" +.IX Subsection "Default implementations" +For each supported abstraction, the \s-1ENGINE\s0 code maintains an internal table +of state to control which implementations are available for a given +abstraction and which should be used by default. These implementations are +registered in the tables and indexed by an 'nid' value, because +abstractions like \s-1EVP_CIPHER\s0 and \s-1EVP_DIGEST\s0 support many distinct +algorithms and modes, and ENGINEs can support arbitrarily many of them. +In the case of other abstractions like \s-1RSA\s0, \s-1DSA\s0, etc, there is only one +\&\*(L"algorithm\*(R" so all implementations implicitly register using the same 'nid' +index. +.PP +When a default \s-1ENGINE\s0 is requested for a given abstraction/algorithm/mode, (eg. +when calling RSA_new_method(\s-1NULL\s0)), a \*(L"get_default\*(R" call will be made to the +\&\s-1ENGINE\s0 subsystem to process the corresponding state table and return a +functional reference to an initialised \s-1ENGINE\s0 whose implementation should be +used. If no \s-1ENGINE\s0 should (or can) be used, it will return \s-1NULL\s0 and the caller +will operate with a \s-1NULL\s0 \s-1ENGINE\s0 handle \- this usually equates to using the +conventional software implementation. In the latter case, OpenSSL will from +then on behave the way it used to before the \s-1ENGINE\s0 \s-1API\s0 existed. +.PP +Each state table has a flag to note whether it has processed this +\&\*(L"get_default\*(R" query since the table was last modified, because to process +this question it must iterate across all the registered ENGINEs in the +table trying to initialise each of them in turn, in case one of them is +operational. If it returns a functional reference to an \s-1ENGINE\s0, it will +also cache another reference to speed up processing future queries (without +needing to iterate across the table). Likewise, it will cache a \s-1NULL\s0 +response if no \s-1ENGINE\s0 was available so that future queries won't repeat the +same iteration unless the state table changes. This behaviour can also be +changed; if the \s-1ENGINE_TABLE_FLAG_NOINIT\s0 flag is set (using +\&\fIENGINE_set_table_flags()\fR), no attempted initialisations will take place, +instead the only way for the state table to return a non-NULL \s-1ENGINE\s0 to the +\&\*(L"get_default\*(R" query will be if one is expressly set in the table. Eg. +\&\fIENGINE_set_default_RSA()\fR does the same job as \fIENGINE_register_RSA()\fR except +that it also sets the state table's cached response for the \*(L"get_default\*(R" +query. In the case of abstractions like \s-1EVP_CIPHER\s0, where implementations are +indexed by 'nid', these flags and cached-responses are distinct for each 'nid' +value. +.SS "Application requirements" +.IX Subsection "Application requirements" +This section will explain the basic things an application programmer should +support to make the most useful elements of the \s-1ENGINE\s0 functionality +available to the user. The first thing to consider is whether the +programmer wishes to make alternative \s-1ENGINE\s0 modules available to the +application and user. OpenSSL maintains an internal linked list of +\&\*(L"visible\*(R" ENGINEs from which it has to operate \- at start-up, this list is +empty and in fact if an application does not call any \s-1ENGINE\s0 \s-1API\s0 calls and +it uses static linking against openssl, then the resulting application +binary will not contain any alternative \s-1ENGINE\s0 code at all. So the first +consideration is whether any/all available \s-1ENGINE\s0 implementations should be +made visible to OpenSSL \- this is controlled by calling the various \*(L"load\*(R" +functions, eg. +.PP +.Vb 9 +\& /* Make the "dynamic" ENGINE available */ +\& void ENGINE_load_dynamic(void); +\& /* Make the CryptoSwift hardware acceleration support available */ +\& void ENGINE_load_cswift(void); +\& /* Make support for nCipher\*(Aqs "CHIL" hardware available */ +\& void ENGINE_load_chil(void); +\& ... +\& /* Make ALL ENGINE implementations bundled with OpenSSL available */ +\& void ENGINE_load_builtin_engines(void); +.Ve +.PP +Having called any of these functions, \s-1ENGINE\s0 objects would have been +dynamically allocated and populated with these implementations and linked +into OpenSSL's internal linked list. At this point it is important to +mention an important \s-1API\s0 function; +.PP +.Vb 1 +\& void ENGINE_cleanup(void); +.Ve +.PP +If no \s-1ENGINE\s0 \s-1API\s0 functions are called at all in an application, then there +are no inherent memory leaks to worry about from the \s-1ENGINE\s0 functionality, +however if any ENGINEs are loaded, even if they are never registered or +used, it is necessary to use the \fIENGINE_cleanup()\fR function to +correspondingly cleanup before program exit, if the caller wishes to avoid +memory leaks. This mechanism uses an internal callback registration table +so that any \s-1ENGINE\s0 \s-1API\s0 functionality that knows it requires cleanup can +register its cleanup details to be called during \fIENGINE_cleanup()\fR. This +approach allows \fIENGINE_cleanup()\fR to clean up after any \s-1ENGINE\s0 functionality +at all that your program uses, yet doesn't automatically create linker +dependencies to all possible \s-1ENGINE\s0 functionality \- only the cleanup +callbacks required by the functionality you do use will be required by the +linker. +.PP +The fact that ENGINEs are made visible to OpenSSL (and thus are linked into +the program and loaded into memory at run-time) does not mean they are +\&\*(L"registered\*(R" or called into use by OpenSSL automatically \- that behaviour +is something for the application to control. Some applications +will want to allow the user to specify exactly which \s-1ENGINE\s0 they want used +if any is to be used at all. Others may prefer to load all support and have +OpenSSL automatically use at run-time any \s-1ENGINE\s0 that is able to +successfully initialise \- ie. to assume that this corresponds to +acceleration hardware attached to the machine or some such thing. There are +probably numerous other ways in which applications may prefer to handle +things, so we will simply illustrate the consequences as they apply to a +couple of simple cases and leave developers to consider these and the +source code to openssl's builtin utilities as guides. +.PP +\&\fIUsing a specific \s-1ENGINE\s0 implementation\fR +.PP +Here we'll assume an application has been configured by its user or admin +to want to use the \*(L"\s-1ACME\s0\*(R" \s-1ENGINE\s0 if it is available in the version of +OpenSSL the application was compiled with. If it is available, it should be +used by default for all \s-1RSA\s0, \s-1DSA\s0, and symmetric cipher operation, otherwise +OpenSSL should use its builtin software as per usual. The following code +illustrates how to approach this; +.PP +.Vb 10 +\& ENGINE *e; +\& const char *engine_id = "ACME"; +\& ENGINE_load_builtin_engines(); +\& e = ENGINE_by_id(engine_id); +\& if(!e) +\& /* the engine isn\*(Aqt available */ +\& return; +\& if(!ENGINE_init(e)) { +\& /* the engine couldn\*(Aqt initialise, release \*(Aqe\*(Aq */ +\& ENGINE_free(e); +\& return; +\& } +\& if(!ENGINE_set_default_RSA(e)) +\& /* This should only happen when \*(Aqe\*(Aq can\*(Aqt initialise, but the previous +\& * statement suggests it did. */ +\& abort(); +\& ENGINE_set_default_DSA(e); +\& ENGINE_set_default_ciphers(e); +\& /* Release the functional reference from ENGINE_init() */ +\& ENGINE_finish(e); +\& /* Release the structural reference from ENGINE_by_id() */ +\& ENGINE_free(e); +.Ve +.PP +\&\fIAutomatically using builtin \s-1ENGINE\s0 implementations\fR +.PP +Here we'll assume we want to load and register all \s-1ENGINE\s0 implementations +bundled with OpenSSL, such that for any cryptographic algorithm required by +OpenSSL \- if there is an \s-1ENGINE\s0 that implements it and can be initialise, +it should be used. The following code illustrates how this can work; +.PP +.Vb 4 +\& /* Load all bundled ENGINEs into memory and make them visible */ +\& ENGINE_load_builtin_engines(); +\& /* Register all of them for every algorithm they collectively implement */ +\& ENGINE_register_all_complete(); +.Ve +.PP +That's all that's required. Eg. the next time OpenSSL tries to set up an +\&\s-1RSA\s0 key, any bundled ENGINEs that implement \s-1RSA_METHOD\s0 will be passed to +\&\fIENGINE_init()\fR and if any of those succeed, that \s-1ENGINE\s0 will be set as the +default for \s-1RSA\s0 use from then on. +.SS "Advanced configuration support" +.IX Subsection "Advanced configuration support" +There is a mechanism supported by the \s-1ENGINE\s0 framework that allows each +\&\s-1ENGINE\s0 implementation to define an arbitrary set of configuration +\&\*(L"commands\*(R" and expose them to OpenSSL and any applications based on +OpenSSL. This mechanism is entirely based on the use of name-value pairs +and assumes \s-1ASCII\s0 input (no unicode or \s-1UTF\s0 for now!), so it is ideal if +applications want to provide a transparent way for users to provide +arbitrary configuration \*(L"directives\*(R" directly to such ENGINEs. It is also +possible for the application to dynamically interrogate the loaded \s-1ENGINE\s0 +implementations for the names, descriptions, and input flags of their +available \*(L"control commands\*(R", providing a more flexible configuration +scheme. However, if the user is expected to know which \s-1ENGINE\s0 device he/she +is using (in the case of specialised hardware, this goes without saying) +then applications may not need to concern themselves with discovering the +supported control commands and simply prefer to pass settings into ENGINEs +exactly as they are provided by the user. +.PP +Before illustrating how control commands work, it is worth mentioning what +they are typically used for. Broadly speaking there are two uses for +control commands; the first is to provide the necessary details to the +implementation (which may know nothing at all specific to the host system) +so that it can be initialised for use. This could include the path to any +driver or config files it needs to load, required network addresses, +smart-card identifiers, passwords to initialise protected devices, +logging information, etc etc. This class of commands typically needs to be +passed to an \s-1ENGINE\s0 \fBbefore\fR attempting to initialise it, ie. before +calling \fIENGINE_init()\fR. The other class of commands consist of settings or +operations that tweak certain behaviour or cause certain operations to take +place, and these commands may work either before or after \fIENGINE_init()\fR, or +in some cases both. \s-1ENGINE\s0 implementations should provide indications of +this in the descriptions attached to builtin control commands and/or in +external product documentation. +.PP +\&\fIIssuing control commands to an \s-1ENGINE\s0\fR +.PP +Let's illustrate by example; a function for which the caller supplies the +name of the \s-1ENGINE\s0 it wishes to use, a table of string-pairs for use before +initialisation, and another table for use after initialisation. Note that +the string-pairs used for control commands consist of a command \*(L"name\*(R" +followed by the command \*(L"parameter\*(R" \- the parameter could be \s-1NULL\s0 in some +cases but the name can not. This function should initialise the \s-1ENGINE\s0 +(issuing the \*(L"pre\*(R" commands beforehand and the \*(L"post\*(R" commands afterwards) +and set it as the default for everything except \s-1RAND\s0 and then return a +boolean success or failure. +.PP +.Vb 10 +\& int generic_load_engine_fn(const char *engine_id, +\& const char **pre_cmds, int pre_num, +\& const char **post_cmds, int post_num) +\& { +\& ENGINE *e = ENGINE_by_id(engine_id); +\& if(!e) return 0; +\& while(pre_num\-\-) { +\& if(!ENGINE_ctrl_cmd_string(e, pre_cmds[0], pre_cmds[1], 0)) { +\& fprintf(stderr, "Failed command (%s \- %s:%s)\en", engine_id, +\& pre_cmds[0], pre_cmds[1] ? pre_cmds[1] : "(NULL)"); +\& ENGINE_free(e); +\& return 0; +\& } +\& pre_cmds += 2; +\& } +\& if(!ENGINE_init(e)) { +\& fprintf(stderr, "Failed initialisation\en"); +\& ENGINE_free(e); +\& return 0; +\& } +\& /* ENGINE_init() returned a functional reference, so free the structural +\& * reference from ENGINE_by_id(). */ +\& ENGINE_free(e); +\& while(post_num\-\-) { +\& if(!ENGINE_ctrl_cmd_string(e, post_cmds[0], post_cmds[1], 0)) { +\& fprintf(stderr, "Failed command (%s \- %s:%s)\en", engine_id, +\& post_cmds[0], post_cmds[1] ? post_cmds[1] : "(NULL)"); +\& ENGINE_finish(e); +\& return 0; +\& } +\& post_cmds += 2; +\& } +\& ENGINE_set_default(e, ENGINE_METHOD_ALL & ~ENGINE_METHOD_RAND); +\& /* Success */ +\& return 1; +\& } +.Ve +.PP +Note that \fIENGINE_ctrl_cmd_string()\fR accepts a boolean argument that can +relax the semantics of the function \- if set non-zero it will only return +failure if the \s-1ENGINE\s0 supported the given command name but failed while +executing it, if the \s-1ENGINE\s0 doesn't support the command name it will simply +return success without doing anything. In this case we assume the user is +only supplying commands specific to the given \s-1ENGINE\s0 so we set this to +\&\s-1FALSE\s0. +.PP +\&\fIDiscovering supported control commands\fR +.PP +It is possible to discover at run-time the names, numerical-ids, descriptions +and input parameters of the control commands supported by an \s-1ENGINE\s0 using a +structural reference. Note that some control commands are defined by OpenSSL +itself and it will intercept and handle these control commands on behalf of the +\&\s-1ENGINE\s0, ie. the \s-1ENGINE\s0's \fIctrl()\fR handler is not used for the control command. +openssl/engine.h defines an index, \s-1ENGINE_CMD_BASE\s0, that all control commands +implemented by ENGINEs should be numbered from. Any command value lower than +this symbol is considered a \*(L"generic\*(R" command is handled directly by the +OpenSSL core routines. +.PP +It is using these \*(L"core\*(R" control commands that one can discover the the control +commands implemented by a given \s-1ENGINE\s0, specifically the commands; +.PP +.Vb 9 +\& #define ENGINE_HAS_CTRL_FUNCTION 10 +\& #define ENGINE_CTRL_GET_FIRST_CMD_TYPE 11 +\& #define ENGINE_CTRL_GET_NEXT_CMD_TYPE 12 +\& #define ENGINE_CTRL_GET_CMD_FROM_NAME 13 +\& #define ENGINE_CTRL_GET_NAME_LEN_FROM_CMD 14 +\& #define ENGINE_CTRL_GET_NAME_FROM_CMD 15 +\& #define ENGINE_CTRL_GET_DESC_LEN_FROM_CMD 16 +\& #define ENGINE_CTRL_GET_DESC_FROM_CMD 17 +\& #define ENGINE_CTRL_GET_CMD_FLAGS 18 +.Ve +.PP +Whilst these commands are automatically processed by the OpenSSL framework code, +they use various properties exposed by each \s-1ENGINE\s0 to process these +queries. An \s-1ENGINE\s0 has 3 properties it exposes that can affect how this behaves; +it can supply a \fIctrl()\fR handler, it can specify \s-1ENGINE_FLAGS_MANUAL_CMD_CTRL\s0 in +the \s-1ENGINE\s0's flags, and it can expose an array of control command descriptions. +If an \s-1ENGINE\s0 specifies the \s-1ENGINE_FLAGS_MANUAL_CMD_CTRL\s0 flag, then it will +simply pass all these \*(L"core\*(R" control commands directly to the \s-1ENGINE\s0's \fIctrl()\fR +handler (and thus, it must have supplied one), so it is up to the \s-1ENGINE\s0 to +reply to these \*(L"discovery\*(R" commands itself. If that flag is not set, then the +OpenSSL framework code will work with the following rules; +.PP +.Vb 9 +\& if no ctrl() handler supplied; +\& ENGINE_HAS_CTRL_FUNCTION returns FALSE (zero), +\& all other commands fail. +\& if a ctrl() handler was supplied but no array of control commands; +\& ENGINE_HAS_CTRL_FUNCTION returns TRUE, +\& all other commands fail. +\& if a ctrl() handler and array of control commands was supplied; +\& ENGINE_HAS_CTRL_FUNCTION returns TRUE, +\& all other commands proceed processing ... +.Ve +.PP +If the \s-1ENGINE\s0's array of control commands is empty then all other commands will +fail, otherwise; \s-1ENGINE_CTRL_GET_FIRST_CMD_TYPE\s0 returns the identifier of +the first command supported by the \s-1ENGINE\s0, \s-1ENGINE_GET_NEXT_CMD_TYPE\s0 takes the +identifier of a command supported by the \s-1ENGINE\s0 and returns the next command +identifier or fails if there are no more, \s-1ENGINE_CMD_FROM_NAME\s0 takes a string +name for a command and returns the corresponding identifier or fails if no such +command name exists, and the remaining commands take a command identifier and +return properties of the corresponding commands. All except +\&\s-1ENGINE_CTRL_GET_FLAGS\s0 return the string length of a command name or description, +or populate a supplied character buffer with a copy of the command name or +description. \s-1ENGINE_CTRL_GET_FLAGS\s0 returns a bitwise-OR'd mask of the following +possible values; +.PP +.Vb 4 +\& #define ENGINE_CMD_FLAG_NUMERIC (unsigned int)0x0001 +\& #define ENGINE_CMD_FLAG_STRING (unsigned int)0x0002 +\& #define ENGINE_CMD_FLAG_NO_INPUT (unsigned int)0x0004 +\& #define ENGINE_CMD_FLAG_INTERNAL (unsigned int)0x0008 +.Ve +.PP +If the \s-1ENGINE_CMD_FLAG_INTERNAL\s0 flag is set, then any other flags are purely +informational to the caller \- this flag will prevent the command being usable +for any higher-level \s-1ENGINE\s0 functions such as \fIENGINE_ctrl_cmd_string()\fR. +\&\*(L"\s-1INTERNAL\s0\*(R" commands are not intended to be exposed to text-based configuration +by applications, administrations, users, etc. These can support arbitrary +operations via \fIENGINE_ctrl()\fR, including passing to and/or from the control +commands data of any arbitrary type. These commands are supported in the +discovery mechanisms simply to allow applications determinie if an \s-1ENGINE\s0 +supports certain specific commands it might want to use (eg. application \*(L"foo\*(R" +might query various ENGINEs to see if they implement \*(L"\s-1FOO_GET_VENDOR_LOGO_GIF\s0\*(R" \- +and \s-1ENGINE\s0 could therefore decide whether or not to support this \*(L"foo\*(R"\-specific +extension). +.SS "Future developments" +.IX Subsection "Future developments" +The \s-1ENGINE\s0 \s-1API\s0 and internal architecture is currently being reviewed. Slated for +possible release in 0.9.8 is support for transparent loading of \*(L"dynamic\*(R" +ENGINEs (built as self-contained shared-libraries). This would allow \s-1ENGINE\s0 +implementations to be provided independently of OpenSSL libraries and/or +OpenSSL-based applications, and would also remove any requirement for +applications to explicitly use the \*(L"dynamic\*(R" \s-1ENGINE\s0 to bind to shared-library +implementations. +.SH "SEE ALSO" +.IX Header "SEE ALSO" +\&\fIrsa\fR\|(3), \fIdsa\fR\|(3), \fIdh\fR\|(3), \fIrand\fR\|(3) |
