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 C<[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. The brackets are required.
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
43 work as expected. The environment variable B<OPENSSL_CONF_INCLUDE> can also be
44 used to specify the path to prepend to all .include paths.
46 There can be optional B<=> character and whitespace characters between
47 B<.include> directive and the path which can be useful in cases the
48 configuration file needs to be loaded by old OpenSSL versions which do
49 not support the B<.include> syntax. They would bail out with error
50 if the B<=> character is not present but with it they just ignore
53 Each section in a configuration file consists of a number of name and
54 value pairs of the form B<name=value>
56 The B<name> string can contain any alphanumeric characters as well as
57 a few punctuation symbols such as B<.> B<,> B<;> and B<_>.
59 The B<value> string consists of the string following the B<=> character
60 until end of line with any leading and trailing white space removed.
62 The value string undergoes variable expansion. This can be done by
63 including the form B<$var> or B<${var}>: this will substitute the value
64 of the named variable in the current section. It is also possible to
65 substitute a value from another section using the syntax B<$section::name>
66 or B<${section::name}>. By using the form B<$ENV::name> environment
67 variables can be substituted. It is also possible to assign values to
68 environment variables by using the name B<ENV::name>, this will work
69 if the program looks up environment variables using the B<CONF> library
70 instead of calling getenv() directly. The value string must not exceed 64k in
71 length after variable expansion. Otherwise an error will occur.
73 It is possible to escape certain characters by using any kind of quote
74 or the B<\> character. By making the last character of a line a B<\>
75 a B<value> string can be spread across multiple lines. In addition
76 the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognized.
78 All expansion and escape rules as described above that apply to B<value>
79 also apply to the path of the B<.include> directive.
81 =head1 OPENSSL LIBRARY CONFIGURATION
83 Applications can automatically configure certain
84 aspects of OpenSSL using the master OpenSSL configuration file, or optionally
85 an alternative configuration file. The B<openssl> utility includes this
86 functionality: any sub command uses the master OpenSSL configuration file
87 unless an option is used in the sub command to use an alternative configuration
90 To enable library configuration the default section needs to contain an
91 appropriate line which points to the main configuration section. The default
92 name is B<openssl_conf> which is used by the B<openssl> utility. Other
93 applications may use an alternative name such as B<myapplication_conf>.
94 All library configuration lines appear in the default section at the start
95 of the configuration file.
97 The configuration section should consist of a set of name value pairs which
98 contain specific module configuration information. The B<name> represents
99 the name of the I<configuration module>. The meaning of the B<value> is
100 module specific: it may, for example, represent a further configuration
101 section containing configuration module specific information. E.g.:
103 # This must be in the default section
104 openssl_conf = openssl_init
108 oid_section = new_oids
109 engines = engine_section
110 providers = provider_section
114 ... new oids here ...
118 ... engine stuff here ...
122 ... provider stuff here ...
124 The features of each configuration module are described below.
126 =head2 ASN1 Object Configuration Module
128 This module has the name B<oid_section>. The value of this variable points
129 to a section containing name value pairs of OIDs: the name is the OID short
130 and long name, the value is the numerical form of the OID. Although some of
131 the B<openssl> utility sub commands already have their own ASN1 OBJECT section
132 functionality not all do. By using the ASN1 OBJECT configuration module
133 B<all> the B<openssl> utility sub commands can see the new objects as well
134 as any compliant applications. For example:
138 some_new_oid = 1.2.3.4
139 some_other_oid = 1.2.3.5
141 It is also possible to set the value to the long name followed
142 by a comma and the numerical OID form. For example:
144 shortName = some object long name, 1.2.3.4
146 =head2 Engine Configuration Module
148 This ENGINE configuration module has the name B<engines>. The value of this
149 variable points to a section containing further ENGINE configuration
152 The section pointed to by B<engines> is a table of engine names (though see
153 B<engine_id> below) and further sections containing configuration information
154 specific to each ENGINE.
156 Each ENGINE specific section is used to set default algorithms, load
157 dynamic, perform initialization and send ctrls. The actual operation performed
158 depends on the I<command> name which is the name of the name value pair. The
159 currently supported commands are listed below.
165 # Configure ENGINE named "foo"
167 # Configure ENGINE named "bar"
171 ... foo ENGINE specific commands ...
174 ... "bar" ENGINE specific commands ...
176 The command B<engine_id> is used to give the ENGINE name. If used this
177 command must be first. For example:
180 # This would normally handle an ENGINE named "foo"
184 # Override default name and use "myfoo" instead.
187 The command B<dynamic_path> loads and adds an ENGINE from the given path. It
188 is equivalent to sending the ctrls B<SO_PATH> with the path argument followed
189 by B<LIST_ADD> with value 2 and B<LOAD> to the dynamic ENGINE. If this is
190 not the required behaviour then alternative ctrls can be sent directly
191 to the dynamic ENGINE using ctrl commands.
193 The command B<init> determines whether to initialize the ENGINE. If the value
194 is B<0> the ENGINE will not be initialized, if B<1> and attempt it made to
195 initialized the ENGINE immediately. If the B<init> command is not present
196 then an attempt will be made to initialize the ENGINE after all commands in
197 its section have been processed.
199 The command B<default_algorithms> sets the default algorithms an ENGINE will
200 supply using the functions ENGINE_set_default_string().
202 If the name matches none of the above command names it is assumed to be a
203 ctrl command which is sent to the ENGINE. The value of the command is the
204 argument to the ctrl command. If the value is the string B<EMPTY> then no
205 value is sent to the command.
212 # Configure ENGINE named "foo"
216 # Load engine from DSO
217 dynamic_path = /some/path/fooengine.so
218 # A foo specific ctrl.
219 some_ctrl = some_value
220 # Another ctrl that doesn't take a value.
222 # Supply all default algorithms
223 default_algorithms = ALL
225 =head2 Provider Configuration Module
227 This provider configuration module has the name B<providers>. The
228 value of this variable points to a section containing further provider
229 configuration information.
231 The section pointed to by B<providers> is a table of provider names
232 (though see B<identity> below) and further sections containing
233 configuration information specific to each provider module.
235 Each provider specific section is used to load its module, perform
236 activation and set parameters to pass to the provider on demand. The
237 actual operation performed depends on the name of the name value pair.
238 The currently supported commands are listed below.
244 # Configure provider named "foo"
246 # Configure provider named "bar"
250 ... "foo" provider specific parameters ...
253 ... "bar" provider specific parameters ...
255 The command B<identity> is used to give the provider name. For example:
258 # This would normally handle a provider named "foo"
262 # Override default name and use "myfoo" instead.
265 The parameter B<module> loads and adds a provider module from the
266 given module path. That path may be a simple filename, a relative
267 path or an absolute path.
269 The parameter B<activate> determines whether to activate the
270 provider. The value has no importance, the presence of the parameter
271 is enough for activation to take place.
273 All parameters in the section as well as sub-sections are made
274 available to the provider.
276 =head2 EVP Configuration Module
278 This module has the name B<alg_section> which points to a section containing
281 The supported algorithm commands are:
285 =item B<default_properties>
287 The value may be anything that is acceptable as a property query
288 string for EVP_set_default_properties().
290 =item B<fips_mode> (deprecated)
292 The value is a boolean that can be B<yes> or B<no>. If the value is
293 B<yes>, this is exactly equivalent to:
295 default_properties = fips=yes
297 If the value is B<no>, nothing happens.
301 These two commands should not be used together, as there is no control
302 over how they affect each other.
303 The use of B<fips_mode> is strongly discouraged and is only present
304 for backward compatibility with earlier OpenSSL FIPS modules.
306 =head2 SSL Configuration Module
308 This module has the name B<ssl_conf> which points to a section containing
311 Each line in the SSL configuration section contains the name of the
312 configuration and the section containing it.
314 Each configuration section consists of command value pairs for B<SSL_CONF>.
315 Each pair will be passed to a B<SSL_CTX> or B<SSL> structure if it calls
316 SSL_CTX_config() or SSL_config() with the appropriate configuration name.
318 Note: any characters before an initial dot in the configuration section are
319 ignored so the same command can be used multiple times.
327 server = server_section
331 RSA.Certificate = server-rsa.pem
332 ECDSA.Certificate = server-ecdsa.pem
335 The system default configuration with name B<system_default> if present will
336 be applied during any creation of the B<SSL_CTX> structure.
338 Example of a configuration with the system default:
344 system_default = system_default_sect
346 [system_default_sect]
348 MinProtocol = TLSv1.2
353 If a configuration file attempts to expand a variable that doesn't exist
354 then an error is flagged and the file will not load. This can happen
355 if an attempt is made to expand an environment variable that doesn't
356 exist. For example in a previous version of OpenSSL the default OpenSSL
357 master configuration file used the value of B<HOME> which may not be
358 defined on non Unix systems and would cause an error.
360 This can be worked around by including a B<default> section to provide
361 a default value: then if the environment lookup fails the default value
362 will be used instead. For this to work properly the default value must
363 be defined earlier in the configuration file than the expansion. See
364 the B<EXAMPLES> section for an example of how to do this.
366 If the same variable exists in the same section then all but the last
367 value will be silently ignored. In certain circumstances such as with
368 DNs the same field may occur multiple times. This is usually worked
369 around by ignoring any characters before an initial B<.> e.g.
376 Here is a sample configuration file using some of the features
379 # This is the default section.
382 RANDFILE= ${ENV::HOME}/.rnd
383 configdir=$ENV::HOME/config
387 # We are now in section one.
389 # Quotes permit leading and trailing whitespace
390 any = " any variable name "
392 other = A string that can \
393 cover several lines \
394 by including \\ characters
396 message = Hello World\n
400 greeting = $section_one::message
402 This next example shows how to expand environment variables safely.
404 Suppose you want a variable called B<tmpfile> to refer to a
405 temporary filename. The directory it is placed in can determined by
406 the B<TEMP> or B<TMP> environment variables but they may not be
407 set to any value at all. If you just include the environment variable
408 names and the variable doesn't exist then this will cause an error when
409 an attempt is made to load the configuration file. By making use of the
410 default section both values can be looked up with B<TEMP> taking
411 priority and B</tmp> used if neither is defined:
414 # The above value is used if TMP isn't in the environment
416 # The above value is used if TEMP isn't in the environment
417 tmpfile=${ENV::TEMP}/tmp.filename
419 Simple OpenSSL library configuration example to enter FIPS mode:
421 # Default appname: should match "appname" parameter (if any)
422 # supplied to CONF_modules_load_file et al.
423 openssl_conf = openssl_conf_section
425 [openssl_conf_section]
426 # Configuration module list
427 alg_section = evp_sect
430 # Set to "yes" to enter FIPS mode if supported
433 Note: in the above example you will get an error in non FIPS capable versions
436 More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:
438 # Default appname: should match "appname" parameter (if any)
439 # supplied to CONF_modules_load_file et al.
440 openssl_conf = openssl_conf_section
442 [openssl_conf_section]
443 # Configuration module list
444 alg_section = evp_sect
445 oid_section = new_oids
448 # This will have no effect as FIPS mode is off by default.
449 # Set to "yes" to enter FIPS mode, if supported
453 # New OID, just short name
455 # New OID shortname and long name
456 newoid2 = New OID 2 long name, 1.2.3.4.2
458 The above examples can be used with any application supporting library
459 configuration if "openssl_conf" is modified to match the appropriate "appname".
461 For example if the second sample file above is saved to "example.cnf" then
464 OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1
468 0:d=0 hl=2 l= 4 prim: OBJECT :newoid1
470 showing that the OID "newoid1" has been added as "1.2.3.4.1".
476 =item B<OPENSSL_CONF>
478 The path to the config file.
479 Ignored in set-user-ID and set-group-ID programs.
481 =item B<OPENSSL_ENGINES>
483 The path to the engines directory.
484 Ignored in set-user-ID and set-group-ID programs.
486 =item B<OPENSSL_MODULES>
488 The path to the directory with OpenSSL modules, such as providers.
489 Ignored in set-user-ID and set-group-ID programs.
491 =item B<OPENSSL_CONF_INCLUDE>
493 The optional path to prepend to all .include paths.
499 Currently there is no way to include characters using the octal B<\nnn>
500 form. Strings are all null terminated so nulls cannot form part of
503 The escaping isn't quite right: if you want to use sequences like B<\n>
504 you can't use any quote escaping on the same line.
506 Files are loaded in a single pass. This means that an variable expansion
507 will only work if the variables referenced are defined earlier in the
512 An undocumented API, NCONF_WIN32(), used a slightly different set
513 of parsing rules there were intended to be tailored to
514 the Microsoft Windows platform.
515 Specifically, the backslash character was not an escape character and
516 could be used in pathnames, only the double-quote character was recognized,
517 and comments began with a semi-colon.
518 This function was deprecated in OpenSSL 3.0; applications with
519 configuration files using that syntax will have to be modified.
523 L<x509(1)>, L<req(1)>, L<ca(1)>, L<fips_config(5)>
527 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
529 Licensed under the Apache License 2.0 (the "License"). You may not use
530 this file except in compliance with the License. You can obtain a copy
531 in the file LICENSE in the source distribution or at
532 L<https://www.openssl.org/source/license.html>.