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CONFIG(5ossl)                        OpenSSL                       CONFIG(5ossl)


       config - OpenSSL CONF library configuration files


       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

       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 config(5) and config(5).  The
       syntax for defining ASN.1 values is described in ASN1_generate_nconf(3).


       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.

       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

       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

        .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 and 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.

       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

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


       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,

       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

        oid_section = oids
        providers = providers
        alg_section = evp_properties
        ssl_conf = ssl_configuration
        engines = engines
        random = random

        ... new oids here ...

        ... provider stuff here ...

        ... EVP properties here ...

        ... SSL/TLS configuration properties here ...

        ... engine properties here ...

        ... 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

        shortName = a very long OID name,
        newoid1 =
        some_other_oid =

       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:

       will output:

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

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

   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

       Within a provider section, the following names have meaning:

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

            foo = foo_provider

            identity = my_fips_module

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

           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

   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

           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:

        server = server_tls_config
        client = client_tls_config
        system_default = tls_system_default

        ... configuration for SSL/TLS servers ...

        ... 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:

        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 config(5) or
       config(5), 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:

        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:

           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:

            foo = foo_engine

            engine_id = myfoo

           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.

           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.

           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

        foo = foo_engine

        dynamic_path = /some/path/
        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 generator settings.

       Within the random section, the following names have meaning:

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

            random = CTR-DRBG

           The available random bit generators are:

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

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

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

           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.

           This sets the property query used when fetching the randomness


       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

        alg_section = evp_properties

        default_properties = "fips=yes"


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

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

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

           The optional path to prepend to all .include paths.


       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.


       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.


       openssl-x509(1), openssl-req(1), openssl-ca(1), openssl-fipsinstall(1),
       ASN1_generate_nconf(3), EVP_set_default_properties(3)


       Copyright 2000-2023 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

3.1.0                              2023-03-14                      CONFIG(5ossl)

openssl 3.1.0 - Generated Thu Mar 23 16:35:30 CDT 2023
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