4 =for comment openssl_manual_section:5
8 config - OpenSSL CONF library configuration files
12 The OpenSSL CONF library can be used to read configuration files.
13 It is used for the OpenSSL master configuration file B<openssl.cnf>
14 and in a few other places like B<SPKAC> files and certificate extension
15 files for the B<x509> utility. OpenSSL applications can also use the
16 CONF library for their own purposes.
18 A configuration file is divided into a number of sections. Each section
19 starts with a line B<[ section_name ]> and ends when a new section is
20 started or end of file is reached. A section name can consist of
21 alphanumeric characters and underscores.
23 The first section of a configuration file is special and is referred
24 to as the B<default> section this is usually unnamed and is from the
25 start of file until the first named section. When a name is being looked up
26 it is first looked up in a named section (if any) and then the
29 The environment is mapped onto a section called B<ENV>.
31 Comments can be included by preceding them with the B<#> character
33 Each section in a configuration file consists of a number of name and
34 value pairs of the form B<name=value>
36 The B<name> string can contain any alphanumeric characters as well as
37 a few punctuation symbols such as B<.> B<,> B<;> and B<_>.
39 The B<value> string consists of the string following the B<=> character
40 until end of line with any leading and trailing white space removed.
42 The value string undergoes variable expansion. This can be done by
43 including the form B<$var> or B<${var}>: this will substitute the value
44 of the named variable in the current section. It is also possible to
45 substitute a value from another section using the syntax B<$section::name>
46 or B<${section::name}>. By using the form B<$ENV::name> environment
47 variables can be substituted. It is also possible to assign values to
48 environment variables by using the name B<ENV::name>, this will work
49 if the program looks up environment variables using the B<CONF> library
50 instead of calling getenv() directly.
52 It is possible to escape certain characters by using any kind of quote
53 or the B<\> character. By making the last character of a line a B<\>
54 a B<value> string can be spread across multiple lines. In addition
55 the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognized.
57 =head1 OPENSSL LIBRARY CONFIGURATION
59 Applications can automatically configure certain
60 aspects of OpenSSL using the master OpenSSL configuration file, or optionally
61 an alternative configuration file. The B<openssl> utility includes this
62 functionality: any sub command uses the master OpenSSL configuration file
63 unless an option is used in the sub command to use an alternative configuration
66 To enable library configuration the default section needs to contain an
67 appropriate line which points to the main configuration section. The default
68 name is B<openssl_conf> which is used by the B<openssl> utility. Other
69 applications may use an alternative name such as B<myapplicaton_conf>.
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 openssl_conf = openssl_init
81 oid_section = new_oids
82 engines = engine_section
90 ... engine stuff here ...
92 The features of each configuration module are described below.
94 =head2 ASN1 OBJECT CONFIGURATION MODULE
96 This module has the name B<oid_section>. The value of this variable points
97 to a section containing name value pairs of OIDs: the name is the OID short
98 and long name, the value is the numerical form of the OID. Although some of
99 the B<openssl> utility sub commands already have their own ASN1 OBJECT section
100 functionality not all do. By using the ASN1 OBJECT configuration module
101 B<all> the B<openssl> utility sub commands can see the new objects as well
102 as any compliant applications. For example:
106 some_new_oid = 1.2.3.4
107 some_other_oid = 1.2.3.5
109 It is also possible to set the value to the long name followed
110 by a comma and the numerical OID form. For example:
112 shortName = some object long name, 1.2.3.4
114 =head2 ENGINE CONFIGURATION MODULE
116 This ENGINE configuration module has the name B<engines>. The value of this
117 variable points to a section containing further ENGINE configuration
120 The section pointed to by B<engines> is a table of engine names (though see
121 B<engine_id> below) and further sections containing configuration information
122 specific to each ENGINE.
124 Each ENGINE specific section is used to set default algorithms, load
125 dynamic, perform initialization and send ctrls. The actual operation performed
126 depends on the I<command> name which is the name of the name value pair. The
127 currently supported commands are listed below.
133 # Configure ENGINE named "foo"
135 # Configure ENGINE named "bar"
139 ... foo ENGINE specific commands ...
142 ... "bar" ENGINE specific commands ...
144 The command B<engine_id> is used to give the ENGINE name. If used this
145 command must be first. For example:
148 # This would normally handle an ENGINE named "foo"
152 # Override default name and use "myfoo" instead.
155 The command B<dynamic_path> loads and adds an ENGINE from the given path. It
156 is equivalent to sending the ctrls B<SO_PATH> with the path argument followed
157 by B<LIST_ADD> with value 2 and B<LOAD> to the dynamic ENGINE. If this is
158 not the required behaviour then alternative ctrls can be sent directly
159 to the dynamic ENGINE using ctrl commands.
161 The command B<init> determines whether to initialize the ENGINE. If the value
162 is B<0> the ENGINE will not be initialized, if B<1> and attempt it made to
163 initialized the ENGINE immediately. If the B<init> command is not present
164 then an attempt will be made to initialize the ENGINE after all commands in
165 its section have been processed.
167 The command B<default_algorithms> sets the default algorithms an ENGINE will
168 supply using the functions ENGINE_set_default_string().
170 If the name matches none of the above command names it is assumed to be a
171 ctrl command which is sent to the ENGINE. The value of the command is the
172 argument to the ctrl command. If the value is the string B<EMPTY> then no
173 value is sent to the command.
180 # Configure ENGINE named "foo"
184 # Load engine from DSO
185 dynamic_path = /some/path/fooengine.so
186 # A foo specific ctrl.
187 some_ctrl = some_value
188 # Another ctrl that doesn't take a value.
190 # Supply all default algorithms
191 default_algorithms = ALL
193 =head2 EVP CONFIGURATION MODULE
195 This modules has the name B<alg_section> which points to a section containing
198 Currently the only algorithm command supported is B<fips_mode> whose
199 value should be a boolean string such as B<on> or B<off>. If the value is
200 B<on> this attempt to enter FIPS mode. If the call fails or the library is
201 not FIPS capable then an error occurs.
205 alg_section = evp_settings
211 =head2 SSL CONFIGURATION MODULE
213 This module has the name B<ssl_conf> which points to a section containing
216 Each line in the SSL configuration section contains the name of the
217 configuration and the section containing it.
219 Each configuration section consists of command value pairs for B<SSL_CONF>.
220 Each pair will be passed to a B<SSL_CTX> or B<SSL> structure if it calls
221 SSL_CTX_config() or SSL_config() with the appropriate configuration name.
223 Note: any characters before an initial dot in the configuration section are
224 ignored so the same command can be used multiple times.
232 server = server_section
236 RSA.Certificate = server-rsa.pem
237 ECDSA.Certificate = server-ecdsa.pem
242 If a configuration file attempts to expand a variable that doesn't exist
243 then an error is flagged and the file will not load. This can happen
244 if an attempt is made to expand an environment variable that doesn't
245 exist. For example in a previous version of OpenSSL the default OpenSSL
246 master configuration file used the value of B<HOME> which may not be
247 defined on non Unix systems and would cause an error.
249 This can be worked around by including a B<default> section to provide
250 a default value: then if the environment lookup fails the default value
251 will be used instead. For this to work properly the default value must
252 be defined earlier in the configuration file than the expansion. See
253 the B<EXAMPLES> section for an example of how to do this.
255 If the same variable exists in the same section then all but the last
256 value will be silently ignored. In certain circumstances such as with
257 DNs the same field may occur multiple times. This is usually worked
258 around by ignoring any characters before an initial B<.> e.g.
265 Here is a sample configuration file using some of the features
268 # This is the default section.
271 RANDFILE= ${ENV::HOME}/.rnd
272 configdir=$ENV::HOME/config
276 # We are now in section one.
278 # Quotes permit leading and trailing whitespace
279 any = " any variable name "
281 other = A string that can \
282 cover several lines \
283 by including \\ characters
285 message = Hello World\n
289 greeting = $section_one::message
291 This next example shows how to expand environment variables safely.
293 Suppose you want a variable called B<tmpfile> to refer to a
294 temporary filename. The directory it is placed in can determined by
295 the the B<TEMP> or B<TMP> environment variables but they may not be
296 set to any value at all. If you just include the environment variable
297 names and the variable doesn't exist then this will cause an error when
298 an attempt is made to load the configuration file. By making use of the
299 default section both values can be looked up with B<TEMP> taking
300 priority and B</tmp> used if neither is defined:
303 # The above value is used if TMP isn't in the environment
305 # The above value is used if TEMP isn't in the environment
306 tmpfile=${ENV::TEMP}/tmp.filename
308 Simple OpenSSL library configuration example to enter FIPS mode:
310 # Default appname: should match "appname" parameter (if any)
311 # supplied to CONF_modules_load_file et al.
312 openssl_conf = openssl_conf_section
314 [openssl_conf_section]
315 # Configuration module list
316 alg_section = evp_sect
319 # Set to "yes" to enter FIPS mode if supported
322 Note: in the above example you will get an error in non FIPS capable versions
325 More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:
327 # Default appname: should match "appname" parameter (if any)
328 # supplied to CONF_modules_load_file et al.
329 openssl_conf = openssl_conf_section
331 [openssl_conf_section]
332 # Configuration module list
333 alg_section = evp_sect
334 oid_section = new_oids
337 # This will have no effect as FIPS mode is off by default.
338 # Set to "yes" to enter FIPS mode, if supported
342 # New OID, just short name
344 # New OID shortname and long name
345 newoid2 = New OID 2 long name, 1.2.3.4.2
347 The above examples can be used with with any application supporting library
348 configuration if "openssl_conf" is modified to match the appropriate "appname".
350 For example if the second sample file above is saved to "example.cnf" then
353 OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1
357 0:d=0 hl=2 l= 4 prim: OBJECT :newoid1
359 showing that the OID "newoid1" has been added as "1.2.3.4.1".
363 Currently there is no way to include characters using the octal B<\nnn>
364 form. Strings are all null terminated so nulls cannot form part of
367 The escaping isn't quite right: if you want to use sequences like B<\n>
368 you can't use any quote escaping on the same line.
370 Files are loaded in a single pass. This means that an variable expansion
371 will only work if the variables referenced are defined earlier in the
376 L<x509(1)>, L<req(1)>, L<ca(1)>