5 config - OpenSSL CONF library configuration files
9 The OpenSSL CONF library can be used to read configuration files.
10 It is used for the OpenSSL master configuration file B<openssl.cnf>
11 and in a few other places like B<SPKAC> files and certificate extension
12 files for the B<x509> utility. OpenSSL applications can also use the
13 CONF library for their own purposes.
15 A configuration file is divided into a number of sections. Each section
16 starts with a line B<[ section_name ]> and ends when a new section is
17 started or end of file is reached. A section name can consist of
18 alphanumeric characters and underscores.
20 The first section of a configuration file is special and is referred
21 to as the B<default> section. This section is usually unnamed and spans from the
22 start of file until the first named section. When a name is being looked up
23 it is first looked up in a named section (if any) and then the
26 The environment is mapped onto a section called B<ENV>.
28 Comments can be included by preceding them with the B<#> character
30 Other files can be included using the B<.include> directive followed
31 by a path. If the path points to a directory all files with
32 names ending with B<.cnf> or B<.conf> are included from the directory.
33 Recursive inclusion of directories from files in such directory is not
34 supported. That means the files in the included directory can also contain
35 B<.include> directives but only inclusion of regular files is supported
36 there. The inclusion of directories is not supported on systems without
39 It is strongly recommended to use absolute paths with the B<.include>
40 directive. Relative paths are evaluated based on the application current
41 working directory so unless the configuration file containing the
42 B<.include> directive is application specific the inclusion will not
45 There can be optional B<=> character and whitespace characters between
46 B<.include> directive and the path which can be useful in cases the
47 configuration file needs to be loaded by old OpenSSL versions which do
48 not support the B<.include> syntax. They would bail out with error
49 if the B<=> character is not present but with it they just ignore
52 Each section in a configuration file consists of a number of name and
53 value pairs of the form B<name=value>
55 The B<name> string can contain any alphanumeric characters as well as
56 a few punctuation symbols such as B<.> B<,> B<;> and B<_>.
58 The B<value> string consists of the string following the B<=> character
59 until end of line with any leading and trailing white space removed.
61 The value string undergoes variable expansion. This can be done by
62 including the form B<$var> or B<${var}>: this will substitute the value
63 of the named variable in the current section. It is also possible to
64 substitute a value from another section using the syntax B<$section::name>
65 or B<${section::name}>. By using the form B<$ENV::name> environment
66 variables can be substituted. It is also possible to assign values to
67 environment variables by using the name B<ENV::name>, this will work
68 if the program looks up environment variables using the B<CONF> library
69 instead of calling getenv() directly. The value string must not exceed 64k in
70 length after variable expansion. Otherwise an error will occur.
72 It is possible to escape certain characters by using any kind of quote
73 or the B<\> character. By making the last character of a line a B<\>
74 a B<value> string can be spread across multiple lines. In addition
75 the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognized.
77 All expansion and escape rules as described above that apply to B<value>
78 also apply to the path of the B<.include> directive.
80 =head1 OPENSSL LIBRARY CONFIGURATION
82 Applications can automatically configure certain
83 aspects of OpenSSL using the master OpenSSL configuration file, or optionally
84 an alternative configuration file. The B<openssl> utility includes this
85 functionality: any sub command uses the master OpenSSL configuration file
86 unless an option is used in the sub command to use an alternative configuration
89 To enable library configuration the default section needs to contain an
90 appropriate line which points to the main configuration section. The default
91 name is B<openssl_conf> which is used by the B<openssl> utility. Other
92 applications may use an alternative name such as B<myapplication_conf>.
93 All library configuration lines appear in the default section at the start
94 of the configuration file.
96 The configuration section should consist of a set of name value pairs which
97 contain specific module configuration information. The B<name> represents
98 the name of the I<configuration module>. The meaning of the B<value> is
99 module specific: it may, for example, represent a further configuration
100 section containing configuration module specific information. E.g.:
102 # This must be in the default section
103 openssl_conf = openssl_init
107 oid_section = new_oids
108 engines = engine_section
109 providers = provider_section
113 ... new oids here ...
117 ... engine stuff here ...
121 ... provider stuff here ...
123 The features of each configuration module are described below.
125 =head2 ASN1 Object Configuration Module
127 This module has the name B<oid_section>. The value of this variable points
128 to a section containing name value pairs of OIDs: the name is the OID short
129 and long name, the value is the numerical form of the OID. Although some of
130 the B<openssl> utility sub commands already have their own ASN1 OBJECT section
131 functionality not all do. By using the ASN1 OBJECT configuration module
132 B<all> the B<openssl> utility sub commands can see the new objects as well
133 as any compliant applications. For example:
137 some_new_oid = 1.2.3.4
138 some_other_oid = 1.2.3.5
140 It is also possible to set the value to the long name followed
141 by a comma and the numerical OID form. For example:
143 shortName = some object long name, 1.2.3.4
145 =head2 Engine Configuration Module
147 This ENGINE configuration module has the name B<engines>. The value of this
148 variable points to a section containing further ENGINE configuration
151 The section pointed to by B<engines> is a table of engine names (though see
152 B<engine_id> below) and further sections containing configuration information
153 specific to each ENGINE.
155 Each ENGINE specific section is used to set default algorithms, load
156 dynamic, perform initialization and send ctrls. The actual operation performed
157 depends on the I<command> name which is the name of the name value pair. The
158 currently supported commands are listed below.
164 # Configure ENGINE named "foo"
166 # Configure ENGINE named "bar"
170 ... foo ENGINE specific commands ...
173 ... "bar" ENGINE specific commands ...
175 The command B<engine_id> is used to give the ENGINE name. If used this
176 command must be first. For example:
179 # This would normally handle an ENGINE named "foo"
183 # Override default name and use "myfoo" instead.
186 The command B<dynamic_path> loads and adds an ENGINE from the given path. It
187 is equivalent to sending the ctrls B<SO_PATH> with the path argument followed
188 by B<LIST_ADD> with value 2 and B<LOAD> to the dynamic ENGINE. If this is
189 not the required behaviour then alternative ctrls can be sent directly
190 to the dynamic ENGINE using ctrl commands.
192 The command B<init> determines whether to initialize the ENGINE. If the value
193 is B<0> the ENGINE will not be initialized, if B<1> and attempt it made to
194 initialized the ENGINE immediately. If the B<init> command is not present
195 then an attempt will be made to initialize the ENGINE after all commands in
196 its section have been processed.
198 The command B<default_algorithms> sets the default algorithms an ENGINE will
199 supply using the functions ENGINE_set_default_string().
201 If the name matches none of the above command names it is assumed to be a
202 ctrl command which is sent to the ENGINE. The value of the command is the
203 argument to the ctrl command. If the value is the string B<EMPTY> then no
204 value is sent to the command.
211 # Configure ENGINE named "foo"
215 # Load engine from DSO
216 dynamic_path = /some/path/fooengine.so
217 # A foo specific ctrl.
218 some_ctrl = some_value
219 # Another ctrl that doesn't take a value.
221 # Supply all default algorithms
222 default_algorithms = ALL
224 =head2 Provider Configuration Module
226 This provider configuration module has the name B<providers>. The
227 value of this variable points to a section containing further provider
228 configuration information.
230 The section pointed to by B<providers> is a table of provider names
231 (though see B<identity> below) and further sections containing
232 configuration information specific to each provider module.
234 Each provider specific section is used to load its module, perform
235 activation and set parameters to pass to the provider on demand. The
236 actual operation performed depends on the name of the name value pair.
237 The currently supported commands are listed below.
243 # Configure provider named "foo"
245 # Configure provider named "bar"
249 ... "foo" provider specific parameters ...
252 ... "bar" provider specific parameters ...
254 The command B<identity> is used to give the provider name. For example:
257 # This would normally handle a provider named "foo"
261 # Override default name and use "myfoo" instead.
264 The parameter B<module> loads and adds a provider module from the
265 given module path. That path may be a simple file name, a relative
266 path or an absolute path.
268 The parameter B<activate> determines whether to activate the
269 provider. The value has no importance, the presence of the parameter
270 is enough for activation to take place.
272 All parameters in the section as well as sub-sections are made
273 available to the provider.
275 =head2 EVP Configuration Module
277 This module has the name B<alg_section> which points to a section containing
280 The supported algorithm commands are:
284 =item B<default_properties>
286 The value may be anything that is acceptable as a property query
287 string for EVP_set_default_properties().
289 =item B<fips_mode> (deprecated)
291 The value is a boolean that can be B<yes> or B<no>. If the value is
292 B<yes>, this is exactly equivalent to:
294 default_properties = fips=yes
296 If the value is B<no>, nothing happens.
300 These two commands should not be used together, as there is no control
301 over how they affect each other.
302 The use of B<fips_mode> is strongly discouraged and is only present
303 for backward compatibility with earlier OpenSSL FIPS modules.
305 =head2 SSL Configuration Module
307 This module has the name B<ssl_conf> which points to a section containing
310 Each line in the SSL configuration section contains the name of the
311 configuration and the section containing it.
313 Each configuration section consists of command value pairs for B<SSL_CONF>.
314 Each pair will be passed to a B<SSL_CTX> or B<SSL> structure if it calls
315 SSL_CTX_config() or SSL_config() with the appropriate configuration name.
317 Note: any characters before an initial dot in the configuration section are
318 ignored so the same command can be used multiple times.
326 server = server_section
330 RSA.Certificate = server-rsa.pem
331 ECDSA.Certificate = server-ecdsa.pem
334 The system default configuration with name B<system_default> if present will
335 be applied during any creation of the B<SSL_CTX> structure.
337 Example of a configuration with the system default:
343 system_default = system_default_sect
345 [system_default_sect]
347 MinProtocol = TLSv1.2
352 If a configuration file attempts to expand a variable that doesn't exist
353 then an error is flagged and the file will not load. This can happen
354 if an attempt is made to expand an environment variable that doesn't
355 exist. For example in a previous version of OpenSSL the default OpenSSL
356 master configuration file used the value of B<HOME> which may not be
357 defined on non Unix systems and would cause an error.
359 This can be worked around by including a B<default> section to provide
360 a default value: then if the environment lookup fails the default value
361 will be used instead. For this to work properly the default value must
362 be defined earlier in the configuration file than the expansion. See
363 the B<EXAMPLES> section for an example of how to do this.
365 If the same variable exists in the same section then all but the last
366 value will be silently ignored. In certain circumstances such as with
367 DNs the same field may occur multiple times. This is usually worked
368 around by ignoring any characters before an initial B<.> e.g.
375 Here is a sample configuration file using some of the features
378 # This is the default section.
381 RANDFILE= ${ENV::HOME}/.rnd
382 configdir=$ENV::HOME/config
386 # We are now in section one.
388 # Quotes permit leading and trailing whitespace
389 any = " any variable name "
391 other = A string that can \
392 cover several lines \
393 by including \\ characters
395 message = Hello World\n
399 greeting = $section_one::message
401 This next example shows how to expand environment variables safely.
403 Suppose you want a variable called B<tmpfile> to refer to a
404 temporary filename. The directory it is placed in can determined by
405 the B<TEMP> or B<TMP> environment variables but they may not be
406 set to any value at all. If you just include the environment variable
407 names and the variable doesn't exist then this will cause an error when
408 an attempt is made to load the configuration file. By making use of the
409 default section both values can be looked up with B<TEMP> taking
410 priority and B</tmp> used if neither is defined:
413 # The above value is used if TMP isn't in the environment
415 # The above value is used if TEMP isn't in the environment
416 tmpfile=${ENV::TEMP}/tmp.filename
418 Simple OpenSSL library configuration example to enter FIPS mode:
420 # Default appname: should match "appname" parameter (if any)
421 # supplied to CONF_modules_load_file et al.
422 openssl_conf = openssl_conf_section
424 [openssl_conf_section]
425 # Configuration module list
426 alg_section = evp_sect
429 # Set to "yes" to enter FIPS mode if supported
432 Note: in the above example you will get an error in non FIPS capable versions
435 More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:
437 # Default appname: should match "appname" parameter (if any)
438 # supplied to CONF_modules_load_file et al.
439 openssl_conf = openssl_conf_section
441 [openssl_conf_section]
442 # Configuration module list
443 alg_section = evp_sect
444 oid_section = new_oids
447 # This will have no effect as FIPS mode is off by default.
448 # Set to "yes" to enter FIPS mode, if supported
452 # New OID, just short name
454 # New OID shortname and long name
455 newoid2 = New OID 2 long name, 1.2.3.4.2
457 The above examples can be used with any application supporting library
458 configuration if "openssl_conf" is modified to match the appropriate "appname".
460 For example if the second sample file above is saved to "example.cnf" then
463 OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1
467 0:d=0 hl=2 l= 4 prim: OBJECT :newoid1
469 showing that the OID "newoid1" has been added as "1.2.3.4.1".
475 =item B<OPENSSL_CONF>
477 The path to the config file.
478 Ignored in set-user-ID and set-group-ID programs.
480 =item B<OPENSSL_ENGINES>
482 The path to the engines directory.
483 Ignored in set-user-ID and set-group-ID programs.
485 =item B<OPENSSL_MODULES>
487 The path to the directory with OpenSSL modules, such as providers.
488 Ignored in set-user-ID and set-group-ID programs.
494 Currently there is no way to include characters using the octal B<\nnn>
495 form. Strings are all null terminated so nulls cannot form part of
498 The escaping isn't quite right: if you want to use sequences like B<\n>
499 you can't use any quote escaping on the same line.
501 Files are loaded in a single pass. This means that an variable expansion
502 will only work if the variables referenced are defined earlier in the
507 L<x509(1)>, L<req(1)>, L<ca(1)>
511 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
513 Licensed under the Apache License 2.0 (the "License"). You may not use
514 this file except in compliance with the License. You can obtain a copy
515 in the file LICENSE in the source distribution or at
516 L<https://www.openssl.org/source/license.html>.