NAME

       config - OpenSSL CONF library configuration files

DESCRIPTION

       This page documents the syntax of OpenSSL configuration files, as parsed by NCONF_load(3) and related
       functions.  This format is used by many of the OpenSSL commands, and to initialize the libraries when
       used by any application.

       The first part describes the general syntax of the configuration files, and subsequent sections describe
       the semantics of individual modules. Other modules are described in fips_config(5) and x509v3_config(5).
       The syntax for defining ASN.1 values is described in ASN1_generate_nconf(3).

SYNTAX

       A configuration file is a series of lines.  Blank lines, and whitespace between the elements of a line,
       have no significance. A comment starts with a # character; the rest of the line is ignored. If the # is
       the first non-space character in a line, the entire line is ignored.

   Directives
       Two directives can be used to control the parsing of configuration files: .include and .pragma.

       For compatibility with older versions of OpenSSL, an equal sign after the directive will be ignored.
       Older versions will treat it as an assignment, so care should be taken if the difference in semantics is
       important.

       A file can include other files using the include syntax:

         .include [=] pathname

       If pathname is a simple filename, that file is included directly at that point.  Included files can have
       .include statements that specify other files.  If pathname is a directory, all files within that
       directory that have a ".cnf" or ".conf" extension will be included.  (This is only available on systems
       with POSIX IO support.)  Any sub-directories found inside the pathname are ignored.  Similarly, if a file
       is opened while scanning a directory, and that file has an .include directive that specifies a directory,
       that is also ignored.

       As a general rule, the pathname should be an absolute path; this can be enforced with the abspath and
       includedir pragmas, described below.  The environment variable OPENSSL_CONF_INCLUDE, if it exists, is
       prepended to all relative pathnames.  If the pathname is still relative, it is interpreted based on the
       current working directory.

       To require all file inclusions to name absolute paths, use the following directive:

        .pragma [=] abspath:value

       The default behavior, where the value is false or off, is to allow relative paths. To require all
       .include pathnames to be absolute paths, use a value of true or on.

       In these files, the dollar sign, $, is used to reference a variable, as described below.  On some
       platforms, however, it is common to treat $ as a regular character in symbol names.  Supporting this
       behavior can be done with the following directive:

        .pragma [=] dollarid:value

       The default behavior, where the value is false or off, is to treat the dollarsign as indicating a
       variable name; "foo$bar" is interpreted as "foo" followed by the expansion of the variable "bar". If
       value is true or on, then "foo$bar" is a single seven-character name nad variable expansions must be
       specified using braces or parentheses.

        .pragma [=] includedir:value

       If a relative pathname is specified in the .include directive, and the OPENSSL_CONF_INCLUDE environment
       variable doesn't exist, then the value of the includedir pragma, if it exists, is prepended to the
       pathname.

   Settings
       A configuration file is divided into a number of sections.  A section begins with the section name in
       square brackets, and ends when a new section starts, or at the end of the file.  The section name can
       consist of alphanumeric characters and underscores.  Whitespace between the name and the brackets is
       removed.

       The first section of a configuration file is special and is referred to as the default section. This
       section is usually unnamed and spans from the start of file until the first named section. When a name is
       being looked up, it is first looked up in the current or named section, and then the default section if
       necessary.

       The environment is mapped onto a section called ENV.

       Within a section are a series of name/value assignments, described in more detail below.  As a reminder,
       the square brackets shown in this example are required, not optional:

        [ section ]
        name1 = This is value1
        name2 = Another value
        ...
        [ newsection ]
        name1 = New value1
        name3 = Value 3

       The name can contain any alphanumeric characters as well as a few punctuation symbols such as . , ; and
       _.  Whitespace after the name and before the equal sign is ignored.

       If a name is repeated in the same section, then all but the last value are ignored. In certain
       circumstances, such as with Certificate DNs, the same field may occur multiple times.  In order to
       support this, commands like openssl-req(1) ignore any leading text that is preceded with a period. For
       example:

        1.OU = First OU
        2.OU = Second OU

       The value consists of the string following the = character until end of line with any leading and
       trailing whitespace removed.

       The value string undergoes variable expansion. The text $var or "${var}" inserts the value of the named
       variable from the current section.  To use a value from another section use $section::name or
       "${section::name}".  By using $ENV::name, the value of the specified environment variable will be
       substituted.

       Variables must be defined before their value is referenced, otherwise an error is flagged and the file
       will not load.  This can be worked around by specifying a default value in the default section before the
       variable is used.

       Any name/value settings in an ENV section are available to the configuration file, but are not propagated
       to the environment.

       It is an error if the value ends up longer than 64k.

       It is possible to escape certain characters by using a single ' or double " quote around the value, or
       using a backslash \ before the character, By making the last character of a line a \ a value string can
       be spread across multiple lines. In addition the sequences \n, \r, \b and \t are recognized.

       The expansion and escape rules as described above that apply to value also apply to the pathname of the
       .include directive.

OPENSSL LIBRARY CONFIGURATION

       The sections below use the informal term module to refer to a part of the OpenSSL functionality. This is
       not the same as the formal term FIPS module, for example.

       The OpenSSL configuration looks up the value of openssl_conf in the default section and takes that as the
       name of a section that specifies how to configure any modules in the library. It is not an error to leave
       any module in its default configuration. An application can specify a different name by calling
       CONF_modules_load_file(), for example, directly.

       OpenSSL also looks up the value of config_diagnostics.  If this exists and has a nonzero numeric value,
       any error suppressing flags passed to CONF_modules_load() will be ignored.  This is useful for diagnosing
       misconfigurations but its use in production requires additional consideration.  With this option enabled,
       a configuration error will completely prevent access to a service.  Without this option and in the
       presence of a configuration error, access will be allowed but the desired configuration will not be used.

        # These must be in the default section
        config_diagnostics = 1
        openssl_conf = openssl_init

        [openssl_init]
        oid_section = oids
        providers = providers
        alg_section = evp_properties
        ssl_conf = ssl_configuration
        engines = engines
        random = random

        [oids]
        ... new oids here ...

        [providers]
        ... provider stuff here ...

        [evp_properties]
        ... EVP properties here ...

        [ssl_configuration]
        ... SSL/TLS configuration properties here ...

        [engines]
        ... engine properties here ...

        [random]
        ... random properties here ...

       The semantics of each module are described below. The phrase "in the initialization section" refers to
       the section identified by the openssl_conf or other name (given as openssl_init in the example above).
       The examples below assume the configuration above is used to specify the individual sections.

   ASN.1 Object Identifier Configuration
       The name oid_section in the initialization section names the section containing name/value pairs of
       OID's.  The name is the short name; the value is an optional long name followed by a comma, and the
       numeric value.  While some OpenSSL commands have their own section for specifying OID's, this section
       makes them available to all commands and applications.

        [oids]
        shortName = a very long OID name, 1.2.3.4
        newoid1 = 1.2.3.4.1
        some_other_oid = 1.2.3.5

       If a full configuration with the above fragment is in the file example.cnf, then the following command
       line:

        OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1

       will output:

        0:d=0  hl=2 l=   4 prim: OBJECT            :newoid1

       showing that the OID "newoid1" has been added as "1.2.3.4.1".

   Provider Configuration
       The name providers in the initialization section names the section containing cryptographic provider
       configuration. The name/value assignments in this section each name a provider, and point to the
       configuration section for that provider. The provider-specific section is used to specify how to load the
       module, activate it, and set other parameters.

       Within a provider section, the following names have meaning:

       identity
           This is used to specify an alternate name, overriding the default name specified in the list of
           providers.  For example:

            [providers]
            foo = foo_provider

            [foo_provider]
            identity = my_fips_module

       module
           Specifies the pathname of the module (typically a shared library) to load.

       activate
           If present, the module is activated. The value assigned to this name is not significant.

       All parameters in the section as well as sub-sections are made available to the provider.

       Default provider and its activation

       If no providers are activated explicitly, the default one is activated implicitly.  See
       OSSL_PROVIDER-default(7) for more details.

       If you add a section explicitly activating any other provider(s), you most probably need to explicitly
       activate the default provider, otherwise it becomes unavailable in openssl. It may make the system
       remotely unavailable.

   EVP Configuration
       The name alg_section in the initialization section names the section containing algorithmic properties
       when using the EVP API.

       Within the algorithm properties section, the following names have meaning:

       default_properties
           The value may be anything that is acceptable as a property query string for
           EVP_set_default_properties().

       fips_mode (deprecated)
           The value is a boolean that can be yes or no.  If the value is yes, this is exactly equivalent to:

            default_properties = fips=yes

           If the value is no, nothing happens. Using this name is deprecated, and if used, it must be the only
           name in the section.

   SSL Configuration
       The name ssl_conf in the initialization section names the section containing the list of SSL/TLS
       configurations.  As with the providers, each name in this section identifies a section with the
       configuration for that name. For example:

        [ssl_configuration]
        server = server_tls_config
        client = client_tls_config
        system_default = tls_system_default

        [server_tls_config]
        ... configuration for SSL/TLS servers ...

        [client_tls_config]
        ... configuration for SSL/TLS clients ...

       The configuration name system_default has a special meaning.  If it exists, it is applied whenever an
       SSL_CTX object is created.  For example, to impose system-wide minimum TLS and DTLS protocol versions:

        [tls_system_default]
        MinProtocol = TLSv1.2
        MinProtocol = DTLSv1.2

       The minimum TLS protocol is applied to SSL_CTX objects that are TLS-based, and the minimum DTLS protocol
       to those are DTLS-based.  The same applies also to maximum versions set with MaxProtocol.

       Each configuration section consists of name/value pairs that are parsed by SSL_CONF_cmd(3), which will be
       called by SSL_CTX_config() or SSL_config(), appropriately.  Note that any characters before an initial
       dot in the configuration section are ignored, so that the same command can be used multiple times. This
       probably is most useful for loading different key types, as shown here:

        [server_tls_config]
        RSA.Certificate = server-rsa.pem
        ECDSA.Certificate = server-ecdsa.pem

   Engine Configuration
       The name engines in the initialization section names the section containing the list of ENGINE
       configurations.  As with the providers, each name in this section identifies an engine with the
       configuration for that engine.  The engine-specific section is used to specify how to load the engine,
       activate it, and set other parameters.

       Within an engine section, the following names have meaning:

       engine_id
           This is used to specify an alternate name, overriding the default name specified in the list of
           engines. If present, it must be first.  For example:

            [engines]
            foo = foo_engine

            [foo_engine]
            engine_id = myfoo

       dynamic_path
           This loads and adds an ENGINE from the given path. It is equivalent to sending the ctrls SO_PATH with
           the path argument followed by LIST_ADD with value 2 and LOAD to the dynamic ENGINE.  If this is not
           the required behaviour then alternative ctrls can be sent directly to the dynamic ENGINE using ctrl
           commands.

       init
           This specifies whether to initialize the ENGINE. If the value is 0 the ENGINE will not be
           initialized, if the value is 1 an attempt is made to initialize the ENGINE immediately. If the init
           command is not present then an attempt will be made to initialize the ENGINE after all commands in
           its section have been processed.

       default_algorithms
           This sets the default algorithms an ENGINE will supply using the function
           ENGINE_set_default_string().

       All other names are taken to be the name of a ctrl command that is sent to the ENGINE, and the value is
       the argument passed with the command.  The special value EMPTY means no value is sent with the command.
       For example:

        [engines]
        foo = foo_engine

        [foo_engine]
        dynamic_path = /some/path/fooengine.so
        some_ctrl = some_value
        default_algorithms = ALL
        other_ctrl = EMPTY

   Random Configuration
       The name random in the initialization section names the section containing the random number generater
       settings.

       Within the random section, the following names have meaning:

       random
           This is used to specify the random bit generator.  For example:

            [random]
            random = CTR-DRBG

           The available random bit generators are:

           CTR-DRBG
           HASH-DRBG
           HMAC-DRBG
       cipher
           This specifies what cipher a CTR-DRBG random bit generator will use.  Other random bit generators
           ignore this name.  The default value is AES-256-CTR.

       digest
           This specifies what digest the HASH-DRBG or HMAC-DRBG random bit generators will use.  Other random
           bit generators ignore this name.

       properties
           This sets the property query used when fetching the random bit generator and any underlying
           algorithms.

       seed
           This sets the randomness source that should be used.  By default SEED-SRC will be used outside of the
           FIPS provider.  The FIPS provider uses call backs to access the same randomness sources from outside
           the validated boundary.

       seed_properties
           This sets the property query used when fetching the randomness source.

EXAMPLES

       This example shows how to use quoting and escaping.

        # This is the default section.
        HOME = /temp
        configdir = $ENV::HOME/config

        [ section_one ]
        # Quotes permit leading and trailing whitespace
        any = " any variable name "
        other = A string that can \
        cover several lines \
        by including \\ characters
        message = Hello World\n

        [ section_two ]
        greeting = $section_one::message

       This example shows how to expand environment variables safely.  In this example, the variable tempfile is
       intended to refer to a temporary file, and the environment variable TEMP or TMP, if present, specify the
       directory where the file should be put.  Since the default section is checked if a variable does not
       exist, it is possible to set TMP to default to /tmp, and TEMP to default to TMP.

        # These two lines must be in the default section.
        TMP = /tmp
        TEMP = $ENV::TMP

        # This can be used anywhere
        tmpfile = ${ENV::TEMP}/tmp.filename

       This example shows how to enforce FIPS mode for the application sample.

        sample = fips_config

        [fips_config]
        alg_section = evp_properties

        [evp_properties]
        default_properties = "fips=yes"

ENVIRONMENT

       OPENSSL_CONF
           The path to the config file, or the empty string for none.  Ignored in set-user-ID and set-group-ID
           programs.

       OPENSSL_ENGINES
           The path to the engines directory.  Ignored in set-user-ID and set-group-ID programs.

       OPENSSL_MODULES
           The path to the directory with OpenSSL modules, such as providers.  Ignored in set-user-ID and set-
           group-ID programs.

       OPENSSL_CONF_INCLUDE
           The optional path to prepend to all .include paths.

BUGS

       There is no way to include characters using the octal \nnn form. Strings are all null terminated so nulls
       cannot form part of the value.

       The escaping isn't quite right: if you want to use sequences like \n you can't use any quote escaping on
       the same line.

       The limit that only one directory can be opened and read at a time can be considered a bug and should be
       fixed.

HISTORY

       An undocumented API, NCONF_WIN32(), used a slightly different set of parsing rules there were intended to
       be tailored to the Microsoft Windows platform.  Specifically, the backslash character was not an escape
       character and could be used in pathnames, only the double-quote character was recognized, and comments
       began with a semi-colon.  This function was deprecated in OpenSSL 3.0; applications with configuration
       files using that syntax will have to be modified.

SEE ALSO

       openssl-x509(1), openssl-req(1), openssl-ca(1), openssl-fipsinstall(1), ASN1_generate_nconf(3),
       EVP_set_default_properties(3), CONF_modules_load(3), CONF_modules_load_file(3), fips_config(5), and
       x509v3_config(5).

COPYRIGHT

       Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except in compliance
       with the License.  You can obtain a copy in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.