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 is usually unnamed and is 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 Each section in a configuration file consists of a number of name and
31 value pairs of the form B<name=value>
33 The B<name> string can contain any alphanumeric characters as well as
34 a few punctuation symbols such as B<.> B<,> B<;> and B<_>.
36 The B<value> string consists of the string following the B<=> character
37 until end of line with any leading and trailing white space removed.
39 The value string undergoes variable expansion. This can be done by
40 including the form B<$var> or B<${var}>: this will substitute the value
41 of the named variable in the current section. It is also possible to
42 substitute a value from another section using the syntax B<$section::name>
43 or B<${section::name}>. By using the form B<$ENV::name> environment
44 variables can be substituted. It is also possible to assign values to
45 environment variables by using the name B<ENV::name>, this will work
46 if the program looks up environment variables using the B<CONF> library
47 instead of calling getenv() directly. The value string must not exceed 64k in
48 length after variable expansion. Otherwise an error will occur.
50 It is possible to escape certain characters by using any kind of quote
51 or the B<\> character. By making the last character of a line a B<\>
52 a B<value> string can be spread across multiple lines. In addition
53 the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognized.
55 =head1 OPENSSL LIBRARY CONFIGURATION
57 Applications can automatically configure certain
58 aspects of OpenSSL using the master OpenSSL configuration file, or optionally
59 an alternative configuration file. The B<openssl> utility includes this
60 functionality: any sub command uses the master OpenSSL configuration file
61 unless an option is used in the sub command to use an alternative configuration
64 To enable library configuration the default section needs to contain an
65 appropriate line which points to the main configuration section. The default
66 name is B<openssl_conf> which is used by the B<openssl> utility. Other
67 applications may use an alternative name such as B<myapplication_conf>.
68 All library configuration lines appear in the default section at the start
69 of the configuration file.
71 The configuration section should consist of a set of name value pairs which
72 contain specific module configuration information. The B<name> represents
73 the name of the I<configuration module> the meaning of the B<value> is
74 module specific: it may, for example, represent a further configuration
75 section containing configuration module specific information. E.g.
77 # This must be in the default section
78 openssl_conf = openssl_init
82 oid_section = new_oids
83 engines = engine_section
91 ... engine stuff here ...
93 The features of each configuration module are described below.
95 =head2 ASN1 Object Configuration Module
97 This module has the name B<oid_section>. The value of this variable points
98 to a section containing name value pairs of OIDs: the name is the OID short
99 and long name, the value is the numerical form of the OID. Although some of
100 the B<openssl> utility sub commands already have their own ASN1 OBJECT section
101 functionality not all do. By using the ASN1 OBJECT configuration module
102 B<all> the B<openssl> utility sub commands can see the new objects as well
103 as any compliant applications. For example:
107 some_new_oid = 1.2.3.4
108 some_other_oid = 1.2.3.5
110 It is also possible to set the value to the long name followed
111 by a comma and the numerical OID form. For example:
113 shortName = some object long name, 1.2.3.4
115 =head2 Engine Configuration Module
117 This ENGINE configuration module has the name B<engines>. The value of this
118 variable points to a section containing further ENGINE configuration
121 The section pointed to by B<engines> is a table of engine names (though see
122 B<engine_id> below) and further sections containing configuration information
123 specific to each ENGINE.
125 Each ENGINE specific section is used to set default algorithms, load
126 dynamic, perform initialization and send ctrls. The actual operation performed
127 depends on the I<command> name which is the name of the name value pair. The
128 currently supported commands are listed below.
134 # Configure ENGINE named "foo"
136 # Configure ENGINE named "bar"
140 ... foo ENGINE specific commands ...
143 ... "bar" ENGINE specific commands ...
145 The command B<engine_id> is used to give the ENGINE name. If used this
146 command must be first. For example:
149 # This would normally handle an ENGINE named "foo"
153 # Override default name and use "myfoo" instead.
156 The command B<dynamic_path> loads and adds an ENGINE from the given path. It
157 is equivalent to sending the ctrls B<SO_PATH> with the path argument followed
158 by B<LIST_ADD> with value 2 and B<LOAD> to the dynamic ENGINE. If this is
159 not the required behaviour then alternative ctrls can be sent directly
160 to the dynamic ENGINE using ctrl commands.
162 The command B<init> determines whether to initialize the ENGINE. If the value
163 is B<0> the ENGINE will not be initialized, if B<1> and attempt it made to
164 initialized the ENGINE immediately. If the B<init> command is not present
165 then an attempt will be made to initialize the ENGINE after all commands in
166 its section have been processed.
168 The command B<default_algorithms> sets the default algorithms an ENGINE will
169 supply using the functions ENGINE_set_default_string().
171 If the name matches none of the above command names it is assumed to be a
172 ctrl command which is sent to the ENGINE. The value of the command is the
173 argument to the ctrl command. If the value is the string B<EMPTY> then no
174 value is sent to the command.
181 # Configure ENGINE named "foo"
185 # Load engine from DSO
186 dynamic_path = /some/path/fooengine.so
187 # A foo specific ctrl.
188 some_ctrl = some_value
189 # Another ctrl that doesn't take a value.
191 # Supply all default algorithms
192 default_algorithms = ALL
194 =head2 EVP Configuration Module
196 This modules has the name B<alg_section> which points to a section containing
199 Currently the only algorithm command supported is B<fips_mode> whose
200 value can only be the boolean string B<off>. If B<fips_mode> is set to B<on>,
201 an error occurs as this library version is not FIPS capable.
203 =head2 SSL Configuration Module
205 This module has the name B<ssl_conf> which points to a section containing
208 Each line in the SSL configuration section contains the name of the
209 configuration and the section containing it.
211 Each configuration section consists of command value pairs for B<SSL_CONF>.
212 Each pair will be passed to a B<SSL_CTX> or B<SSL> structure if it calls
213 SSL_CTX_config() or SSL_config() with the appropriate configuration name.
215 Note: any characters before an initial dot in the configuration section are
216 ignored so the same command can be used multiple times.
224 server = server_section
228 RSA.Certificate = server-rsa.pem
229 ECDSA.Certificate = server-ecdsa.pem
234 If a configuration file attempts to expand a variable that doesn't exist
235 then an error is flagged and the file will not load. This can happen
236 if an attempt is made to expand an environment variable that doesn't
237 exist. For example in a previous version of OpenSSL the default OpenSSL
238 master configuration file used the value of B<HOME> which may not be
239 defined on non Unix systems and would cause an error.
241 This can be worked around by including a B<default> section to provide
242 a default value: then if the environment lookup fails the default value
243 will be used instead. For this to work properly the default value must
244 be defined earlier in the configuration file than the expansion. See
245 the B<EXAMPLES> section for an example of how to do this.
247 If the same variable exists in the same section then all but the last
248 value will be silently ignored. In certain circumstances such as with
249 DNs the same field may occur multiple times. This is usually worked
250 around by ignoring any characters before an initial B<.> e.g.
257 Here is a sample configuration file using some of the features
260 # This is the default section.
263 RANDFILE= ${ENV::HOME}/.rnd
264 configdir=$ENV::HOME/config
268 # We are now in section one.
270 # Quotes permit leading and trailing whitespace
271 any = " any variable name "
273 other = A string that can \
274 cover several lines \
275 by including \\ characters
277 message = Hello World\n
281 greeting = $section_one::message
283 This next example shows how to expand environment variables safely.
285 Suppose you want a variable called B<tmpfile> to refer to a
286 temporary filename. The directory it is placed in can determined by
287 the B<TEMP> or B<TMP> environment variables but they may not be
288 set to any value at all. If you just include the environment variable
289 names and the variable doesn't exist then this will cause an error when
290 an attempt is made to load the configuration file. By making use of the
291 default section both values can be looked up with B<TEMP> taking
292 priority and B</tmp> used if neither is defined:
295 # The above value is used if TMP isn't in the environment
297 # The above value is used if TEMP isn't in the environment
298 tmpfile=${ENV::TEMP}/tmp.filename
300 Simple OpenSSL library configuration example to enter FIPS mode:
302 # Default appname: should match "appname" parameter (if any)
303 # supplied to CONF_modules_load_file et al.
304 openssl_conf = openssl_conf_section
306 [openssl_conf_section]
307 # Configuration module list
308 alg_section = evp_sect
311 # Set to "yes" to enter FIPS mode if supported
314 Note: in the above example you will get an error in non FIPS capable versions
317 More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:
319 # Default appname: should match "appname" parameter (if any)
320 # supplied to CONF_modules_load_file et al.
321 openssl_conf = openssl_conf_section
323 [openssl_conf_section]
324 # Configuration module list
325 alg_section = evp_sect
326 oid_section = new_oids
329 # This will have no effect as FIPS mode is off by default.
330 # Set to "yes" to enter FIPS mode, if supported
334 # New OID, just short name
336 # New OID shortname and long name
337 newoid2 = New OID 2 long name, 1.2.3.4.2
339 The above examples can be used with any application supporting library
340 configuration if "openssl_conf" is modified to match the appropriate "appname".
342 For example if the second sample file above is saved to "example.cnf" then
345 OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1
349 0:d=0 hl=2 l= 4 prim: OBJECT :newoid1
351 showing that the OID "newoid1" has been added as "1.2.3.4.1".
355 Currently there is no way to include characters using the octal B<\nnn>
356 form. Strings are all null terminated so nulls cannot form part of
359 The escaping isn't quite right: if you want to use sequences like B<\n>
360 you can't use any quote escaping on the same line.
362 Files are loaded in a single pass. This means that an variable expansion
363 will only work if the variables referenced are defined earlier in the
368 L<x509(1)>, L<req(1)>, L<ca(1)>
372 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
374 Licensed under the OpenSSL license (the "License"). You may not use
375 this file except in compliance with the License. You can obtain a copy
376 in the file LICENSE in the source distribution or at
377 L<https://www.openssl.org/source/license.html>.