config - OpenSSL CONF library configuration files


   The OpenSSL CONF library can be used to read configuration files.  It
   is used for the OpenSSL master configuration file openssl.cnf and in a
   few other places like SPKAC files and certificate extension files for
   the x509 utility. OpenSSL applications can also use the CONF library
   for their own purposes.

   A configuration file is divided into a number of sections. Each section
   starts with a line [ section_name ] and ends when a new section is
   started or end of file is reached. A section name can consist of
   alphanumeric characters and underscores.

   The first section of a configuration file is special and is referred to
   as the default section this is usually unnamed and is from the start of
   file until the first named section. When a name is being looked up it
   is first looked up in a named section (if any) and then the default

   The environment is mapped onto a section called ENV.

   Comments can be included by preceding them with the # character

   Each section in a configuration file consists of a number of name and
   value pairs of the form name=value

   The name string can contain any alphanumeric characters as well as a
   few punctuation symbols such as . , ; and _.

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

   The value string undergoes variable expansion. This can be done by
   including the form $var or ${var}: this will substitute the value of
   the named variable in the current section. It is also possible to
   substitute a value from another section using the syntax $section::name
   or ${section::name}. By using the form $ENV::name environment variables
   can be substituted. It is also possible to assign values to environment
   variables by using the name ENV::name, this will work if the program
   looks up environment variables using the CONF library instead of
   calling getenv() directly.

   It is possible to escape certain characters by using any kind of quote
   or 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.


   In OpenSSL 0.9.7 and later applications can automatically configure
   certain aspects of OpenSSL using the master OpenSSL configuration file,
   or optionally an alternative configuration file. The openssl utility
   includes this functionality: any sub command uses the master OpenSSL
   configuration file unless an option is used in the sub command to use
   an alternative configuration file.

   To enable library configuration the default section needs to contain an
   appropriate line which points to the main configuration section. The
   default name is openssl_conf which is used by the openssl utility.
   Other applications may use an alternative name such as

   The configuration section should consist of a set of name value pairs
   which contain specific module configuration information. The name
   represents the name of the configuration module the meaning of the
   value is module specific: it may, for example, represent a further
   configuration section containing configuration module specific
   information. E.g.

    openssl_conf = openssl_init


    oid_section = new_oids
    engines = engine_section


    ... new oids here ...


    ... engine stuff here ...

   The features of each configuration module are described below.

   This module has the name oid_section. The value of this variable points
   to a section containing name value pairs of OIDs: the name is the OID
   short and long name, the value is the numerical form of the OID.
   Although some of the openssl utility sub commands already have their
   own ASN1 OBJECT section functionality not all do. By using the ASN1
   OBJECT configuration module all the openssl utility sub commands can
   see the new objects as well as any compliant applications. For example:


    some_new_oid =
    some_other_oid =

   In OpenSSL 0.9.8 it is also possible to set the value to the long name
   followed by a comma and the numerical OID form. For example:

    shortName = some object long name,

   This ENGINE configuration module has the name engines. The value of
   this variable points to a section containing further ENGINE
   configuration information.

   The section pointed to by engines is a table of engine names (though
   see engine_id below) and further sections containing configuration
   information specific to each ENGINE.

   Each ENGINE specific section is used to set default algorithms, load
   dynamic, perform initialization and send ctrls. The actual operation
   performed depends on the command name which is the name of the name
   value pair. The currently supported commands are listed below.

   For example:


    # Configure ENGINE named "foo"
    foo = foo_section
    # Configure ENGINE named "bar"
    bar = bar_section

    ... foo ENGINE specific commands ...

    ... "bar" ENGINE specific commands ...

   The command engine_id is used to give the ENGINE name. If used this
   command must be first. For example:

    # This would normally handle an ENGINE named "foo"
    foo = foo_section

    # Override default name and use "myfoo" instead.
    engine_id = myfoo

   The command dynamic_path 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.

   The command init determines whether to initialize the ENGINE. If the
   value is 0 the ENGINE will not be initialized, if 1 and attempt it made
   to initialized 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.

   The command default_algorithms sets the default algorithms an ENGINE
   will supply using the functions ENGINE_set_default_string()

   If the name matches none of the above command names it is assumed to be
   a ctrl command which is sent to the ENGINE. The value of the command is
   the argument to the ctrl command. If the value is the string EMPTY then
   no value is sent to the command.

   For example:


    # Configure ENGINE named "foo"
    foo = foo_section

    # Load engine from DSO
    dynamic_path = /some/path/
    # A foo specific ctrl.
    some_ctrl = some_value
    # Another ctrl that doesn't take a value.
    other_ctrl = EMPTY
    # Supply all default algorithms
    default_algorithms = ALL

   This modules has the name alg_section which points to a section
   containing algorithm commands.

   Currently the only algorithm command supported is fips_mode whose value
   should be a boolean string such as on or off. If the value is on this
   attempt to enter FIPS mode. If the call fails or the library is not
   FIPS capable then an error occurs.

   For example:

    alg_section = evp_settings


    fips_mode = on


   If a configuration file attempts to expand a variable that doesn't
   exist then an error is flagged and the file will not load. This can
   happen if an attempt is made to expand an environment variable that
   doesn't exist. For example in a previous version of OpenSSL the default
   OpenSSL master configuration file used the value of HOME which may not
   be defined on non Unix systems and would cause an error.

   This can be worked around by including a default section to provide a
   default value: then if the environment lookup fails the default value
   will be used instead. For this to work properly the default value must
   be defined earlier in the configuration file than the expansion. See
   the EXAMPLES section for an example of how to do this.

   If the same variable exists in the same section then all but the last
   value will be silently ignored. In certain circumstances such as with
   DNs the same field may occur multiple times. This is usually worked
   around by ignoring any characters before an initial . e.g.

    1.OU="My first OU"
    2.OU="My Second OU"


   Here is a sample configuration file using some of the features
   mentioned above.

    # This is the default section.

    RANDFILE= ${ENV::HOME}/.rnd

    [ section_one ]

    # We are now in 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 next example shows how to expand environment variables safely.

   Suppose you want a variable called tmpfile to refer to a temporary
   filename. The directory it is placed in can determined by the the TEMP
   or TMP environment variables but they may not be set to any value at
   all. If you just include the environment variable names and the
   variable doesn't exist then this will cause an error when an attempt is
   made to load the configuration file. By making use of the default
   section both values can be looked up with TEMP taking priority and /tmp
   used if neither is defined:

    # The above value is used if TMP isn't in the environment
    # The above value is used if TEMP isn't in the environment

   Simple OpenSSL library configuration example to enter FIPS mode:

    # Default appname: should match "appname" parameter (if any)
    # supplied to CONF_modules_load_file et al.
    openssl_conf = openssl_conf_section

    # Configuration module list
    alg_section = evp_sect

    # Set to "yes" to enter FIPS mode if supported
    fips_mode = yes

   Note: in the above example you will get an error in non FIPS capable
   versions of OpenSSL.

   More complex OpenSSL library configuration. Add OID and don't enter
   FIPS mode:

    # Default appname: should match "appname" parameter (if any)
    # supplied to CONF_modules_load_file et al.
    openssl_conf = openssl_conf_section

    # Configuration module list
    alg_section = evp_sect
    oid_section = new_oids

    # This will have no effect as FIPS mode is off by default.
    # Set to "yes" to enter FIPS mode, if supported
    fips_mode = no

    # New OID, just short name
    newoid1 =
    # New OID shortname and long name
    newoid2 = New OID 2 long name,

   The above examples can be used with with any application supporting
   library configuration if "openssl_conf" is modified to match the
   appropriate "appname".

   For example if the second sample file above is saved to "example.cnf"
   then the 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 "".


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

   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.

   Files are loaded in a single pass. This means that an variable
   expansion will only work if the variables referenced are defined
   earlier in the file.


   x509(1), req(1), ca(1)

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