man > FIPS_MODULE(7SSL)

FIPS_MODULE(7SSL)                              OpenSSL                             FIPS_MODULE(7SSL)

NAME
       fips_module - OpenSSL fips module guide

SYNOPSIS
       See the individual manual pages for details.

DESCRIPTION
       This guide details different ways that OpenSSL can be used in conjunction with the FIPS
       module. Which is the correct approach to use will depend on your own specific circumstances
       and what you are attempting to achieve.

       For information related to installing the FIPS module see
       <https://github.com/openssl/openssl/blob/master/README-FIPS.md>.

       Note that the old functions FIPS_mode() and FIPS_mode_set() are no longer present so you must
       remove them from your application if you use them.

       Applications written to use the OpenSSL 3.0 FIPS module should not use any legacy APIs or
       features that avoid the FIPS module. Specifically this includes:

       •   Low level cryptographic APIs (use the high level APIs, such as EVP, instead)

       •   Engines

       •   Any  functions  that  create  or  modify custom "METHODS" (for example EVP_MD_meth_new(),
           EVP_CIPHER_meth_new(), EVP_PKEY_meth_new(), RSA_meth_new(), EC_KEY_METHOD_new(), etc.)

       All of the above APIs are deprecated in OpenSSL 3.0 - so a simple rule is to avoid using  all
       deprecated functions. See migration_guide(7) for a list of deprecated functions.

   Applications running on systems operating in FIPS-approved mode
       When  running on systems that are operating in FIPS-approved mode and no providers are loaded
       explicitly via the application or config, the FIPS module is loaded implicitly as a  fallback
       provider  whenever  an algorithm is fetched for the first time. The "default" provider is not
       loaded implicitly in this case, and must be  loaded  explicitly  if  it  is  required  by  an
       application.

       Every  OSSL_LIB_CTX(3)  is created with "fips=yes" as a default property in this mode so that
       algorithm fetches will only fetch algorithms that define this property and are FIPS-approved.
       To use algorithms that are not FIPS approved,  either  specify  "-fips"  or  "fips=no"  as  a
       property      query      string      with      fetching     functions,     or     use     the
       EVP_default_properties_enable_fips(3) function to remove the default property for a  specific
       OSSL_LIB_CTX.

   Making all applications use the FIPS module by default
       One  simple approach is to cause all applications that are using OpenSSL to only use the FIPS
       module for cryptographic algorithms by default.

       This approach can be done purely via configuration. As long as  applications  are  built  and
       linked  against OpenSSL 3.0 and do not override the loading of the default config file or its
       settings then they can automatically start using the FIPS module without  the  need  for  any
       further code changes.

       To  do  this  the  default OpenSSL config file will have to be modified. The location of this
       config file will depend on the platform, and any options that were  given  during  the  build
       process. You can check the location of the config file by running this command:

           $ openssl version -d
           OPENSSLDIR: "/usr/local/ssl"

       Caution:  Many Operating Systems install OpenSSL by default. It is a common error to not have
       the correct version of OpenSSL in your $PATH. Check that  you  are  running  an  OpenSSL  3.0
       version like this:

           $ openssl version -v
           OpenSSL 3.0.0-dev xx XXX xxxx (Library: OpenSSL 3.0.0-dev xx XXX xxxx)

       The  OPENSSLDIR  value  above  gives  the directory name for where the default config file is
       stored. So in this case the default config file will be called /usr/local/ssl/openssl.cnf.

       Edit the config file to add the following lines near the beginning:

           config_diagnostics = 1
           openssl_conf = openssl_init

           .include /usr/local/ssl/fipsmodule.cnf

           [openssl_init]
           providers = provider_sect

           [provider_sect]
           fips = fips_sect
           base = base_sect

           [base_sect]
           activate = 1

       Obviously the include file location above should match the path and name of the  FIPS  module
       config          file         that         you         installed         earlier.          See
       <https://github.com/openssl/openssl/blob/master/README-FIPS.md>.

       For FIPS usage, it is recommended that the config_diagnostics option is  enabled  to  prevent
       accidental  use  of  non-FIPS validated algorithms via broken or mistaken configuration.  See
       config(5).

       Any applications that use OpenSSL 3.0 and are started after these changes are made will start
       using only the FIPS module unless those  applications  take  explicit  steps  to  avoid  this
       default  behaviour. Note that this configuration also activates the "base" provider. The base
       provider does not include any cryptographic algorithms (and therefore  does  not  impact  the
       validation  status  of  any  cryptographic  operations),  but  does  include other supporting
       algorithms that may be required. It is designed to be  used  in  conjunction  with  the  FIPS
       module.

       This  approach  has the primary advantage that it is simple, and no code changes are required
       in applications in order to benefit from the FIPS module. There  are  some  disadvantages  to
       this approach:

       •   You may not want all applications to use the FIPS module.

           It may be the case that some applications should and some should not use the FIPS module.

       •   If  applications take explicit steps to not load the default config file or set different
           settings.

           This method will not work for these cases.

       •   The algorithms available in the FIPS module are a  subset  of  the  algorithms  that  are
           available in the default OpenSSL Provider.

           If  any  applications  attempt to use any algorithms that are not present, then they will
           fail.

       •   Usage of certain deprecated APIs avoids the use of the FIPS module.

           If any applications use those APIs then the FIPS module will not be used.

   Selectively making applications use the FIPS module by default
       A variation on the above approach is to do the same thing on an individual application basis.
       The default OpenSSL config file depends on the compiled in value for OPENSSLDIR as  described
       in  the section above. However it is also possible to override the config file to be used via
       the OPENSSL_CONF environment variable. For example the following, on  Unix,  will  cause  the
       application to be executed with a non-standard config file location:

           $ OPENSSL_CONF=/my/nondefault/openssl.cnf myapplication

       Using  this mechanism you can control which config file is loaded (and hence whether the FIPS
       module is loaded) on an application by application basis.

       This removes the disadvantage listed above that you may not want all applications to use  the
       FIPS module. All the other advantages and disadvantages still apply.

   Programmatically loading the FIPS module (default library context)
       Applications may choose to load the FIPS provider explicitly rather than relying on config to
       do  this.  The  config  file  is still necessary in order to hold the FIPS module config data
       (such as its self test status and integrity data). But in this case we do  not  automatically
       activate the FIPS provider via that config file.

       To  do  things  this  way  configure  as  per "Making all applications use the FIPS module by
       default" above, but edit the fipsmodule.cnf file to remove or comment out the line which says
       "activate = 1" (note that setting this value to 0 is not sufficient).   This  means  all  the
       required  config  information  will  be  available  to  load  the  FIPS module, but it is not
       automatically loaded when the application starts.  The  FIPS  provider  can  then  be  loaded
       programmatically like this:

           #include <openssl/provider.h>

           int main(void)
           {
               OSSL_PROVIDER *fips;
               OSSL_PROVIDER *base;

               fips = OSSL_PROVIDER_load(NULL, "fips");
               if (fips == NULL) {
                   printf("Failed to load FIPS provider\n");
                   exit(EXIT_FAILURE);
               }
               base = OSSL_PROVIDER_load(NULL, "base");
               if (base == NULL) {
                   OSSL_PROVIDER_unload(fips);
                   printf("Failed to load base provider\n");
                   exit(EXIT_FAILURE);
               }

               /* Rest of application */

               OSSL_PROVIDER_unload(base);
               OSSL_PROVIDER_unload(fips);
               exit(EXIT_SUCCESS);
           }

       Note  that  this  should  be  one of the first things that you do in your application. If any
       OpenSSL functions get called that require the use  of  cryptographic  functions  before  this
       occurs  then,  if  no  provider  has  yet  been  loaded,  then  the  default provider will be
       automatically loaded. If you then later explicitly load the FIPS provider then you will  have
       both  the  FIPS  and  the  default  provider  loaded  at the same time. It is undefined which
       implementation of an algorithm will be used if multiple implementations are available and you
       have not explicitly specified via a property query (see below) which one should be used.

       Also note that in this example we have additionally loaded the "base" provider.  This loads a
       sub-set of algorithms that are also available in the  default  provider  -  specifically  non
       cryptographic  ones which may be used in conjunction with the FIPS provider. For example this
       contains algorithms for encoding and decoding keys. If you decide not  to  load  the  default
       provider then you will usually want to load the base provider instead.

       In  this example we are using the "default" library context. OpenSSL functions operate within
       the scope of a library context. If no  library  context  is  explicitly  specified  then  the
       default  library  context  is  used.  For  further  details  about  library  contexts see the
       OSSL_LIB_CTX(3) man page.

   Loading the FIPS module at the same time as other providers
       It is possible to have the FIPS provider and other providers (such as the  default  provider)
       all  loaded  at  the  same  time  into the same library context. You can use a property query
       string during algorithm fetches to specify which implementation you would like to use.

       For example to fetch an implementation of SHA256 which conforms to  FIPS  standards  you  can
       specify the property query "fips=yes" like this:

           EVP_MD *sha256;

           sha256 = EVP_MD_fetch(NULL, "SHA2-256", "fips=yes");

       If no property query is specified, or more than one implementation matches the property query
       then it is undefined which implementation of a particular algorithm will be returned.

       This  example  shows  an  explicit  request  for an implementation of SHA256 from the default
       provider:

           EVP_MD *sha256;

           sha256 = EVP_MD_fetch(NULL, "SHA2-256", "provider=default");

       It is also possible to set a default property query string. The following  example  sets  the
       default property query of "fips=yes" for all fetches within the default library context:

           EVP_set_default_properties(NULL, "fips=yes");

       If  a  fetch  function  has both an explicit property query specified, and a default property
       query is defined then the two queries are merged together and both apply. The local  property
       query overrides the default properties if the same property name is specified in both.

       There are two important built-in properties that you should be aware of:

       The  "provider"  property enables you to specify which provider you want an implementation to
       be fetched from, e.g. "provider=default" or "provider=fips".  All algorithms implemented in a
       provider have this property set on them.

       There is also the "fips" property. All FIPS  algorithms  match  against  the  property  query
       "fips=yes".  There  are  also  some non-cryptographic algorithms available in the default and
       base providers that also have the "fips=yes" property defined for them. These are the encoder
       and decoder algorithms that can (for example) be used to write out a  key  generated  in  the
       FIPS provider to a file. The encoder and decoder algorithms are not in the FIPS module itself
       but are allowed to be used in conjunction with the FIPS algorithms.

       It  is possible to specify default properties within a config file. For example the following
       config file automatically loads the default and FIPS providers and sets the default  property
       value  to  be  "fips=yes".  Note that this config file does not load the "base" provider. All
       supporting algorithms that are in "base" are also in "default", so it is unnecessary in  this
       case:

           config_diagnostics = 1
           openssl_conf = openssl_init

           .include /usr/local/ssl/fipsmodule.cnf

           [openssl_init]
           providers = provider_sect
           alg_section = algorithm_sect

           [provider_sect]
           fips = fips_sect
           default = default_sect

           [default_sect]
           activate = 1

           [algorithm_sect]
           default_properties = fips=yes

   Programmatically loading the FIPS module (nondefault library context)
       In  addition  to using properties to separate usage of the FIPS module from other usages this
       can also be achieved using library contexts. In this example we create two library  contexts.
       In  one  we  assume the existence of a config file called openssl-fips.cnf that automatically
       loads and configures the FIPS and base providers. The other library context will just use the
       default provider.

           OSSL_LIB_CTX *fips_libctx, *nonfips_libctx;
           OSSL_PROVIDER *defctxnull = NULL;
           EVP_MD *fipssha256 = NULL, *nonfipssha256 = NULL;
           int ret = 1;

           /*
            * Create two nondefault library contexts. One for fips usage and
            * one for non-fips usage
            */
           fips_libctx = OSSL_LIB_CTX_new();
           nonfips_libctx = OSSL_LIB_CTX_new();
           if (fips_libctx == NULL || nonfips_libctx == NULL)
               goto err;

           /* Prevent anything from using the default library context */
           defctxnull = OSSL_PROVIDER_load(NULL, "null");

           /*
            * Load config file for the FIPS library context. We assume that
            * this config file will automatically activate the FIPS and base
            * providers so we don't need to explicitly load them here.
            */
           if (!OSSL_LIB_CTX_load_config(fips_libctx, "openssl-fips.cnf"))
               goto err;

           /*
            * We don't need to do anything special to load the default
            * provider into nonfips_libctx. This happens automatically if no
            * other providers are loaded.
            * Because we don't call OSSL_LIB_CTX_load_config() explicitly for
            * nonfips_libctx it will just use the default config file.
            */

           /* As an example get some digests */

           /* Get a FIPS validated digest */
           fipssha256 = EVP_MD_fetch(fips_libctx, "SHA2-256", NULL);
           if (fipssha256 == NULL)
               goto err;

           /* Get a non-FIPS validated digest */
           nonfipssha256 = EVP_MD_fetch(nonfips_libctx, "SHA2-256", NULL);
           if (nonfipssha256 == NULL)
               goto err;

           /* Use the digests */

           printf("Success\n");
           ret = 0;

           err:
           EVP_MD_free(fipssha256);
           EVP_MD_free(nonfipssha256);
           OSSL_LIB_CTX_free(fips_libctx);
           OSSL_LIB_CTX_free(nonfips_libctx);
           OSSL_PROVIDER_unload(defctxnull);

           return ret;

       Note that we have made use of the special "null" provider here which we load into the default
       library context. We could have chosen to use the default library context for FIPS usage,  and
       just  create one additional library context for other usages - or vice versa. However if code
       has not been converted to use library contexts then  the  default  library  context  will  be
       automatically  used.   This  could  be the case for your own existing applications as well as
       certain parts of OpenSSL itself. Not all parts of OpenSSL are library context aware. If  this
       happens  then  you  could  "accidentally"  use  the  wrong  library  context for a particular
       operation. To be sure this doesn't happen you can load the "null" provider into  the  default
       library context. Because a provider has been explicitly loaded, the default provider will not
       automatically  load.  This means code using the default context by accident will fail because
       no algorithms will be available.

       See "Library Context" in migration_guide(7) for  additional  information  about  the  Library
       Context.

   Using Encoders and Decoders with the FIPS module
       Encoders  and decoders are used to read and write keys or parameters from or to some external
       format (for example a PEM file). If your application generates keys or parameters  that  then
       need  to  be  written  into  PEM or DER format then it is likely that you will need to use an
       encoder to do this.  Similarly  you  need  a  decoder  to  read  previously  saved  keys  and
       parameters. In most cases this will be invisible to you if you are using APIs that existed in
       OpenSSL  1.1.1  or earlier such as i2d_PrivateKey(3). However the appropriate encoder/decoder
       will need to be available in the library context associated with the key or parameter object.
       The built-in OpenSSL encoders and decoders are implemented  in  both  the  default  and  base
       providers  and  are not in the FIPS module boundary. However since they are not cryptographic
       algorithms themselves it is still possible to use them in conjunction with the  FIPS  module,
       and  therefore these encoders/decoders have the "fips=yes" property against them.  You should
       ensure that either the default or base provider is loaded into the library  context  in  this
       case.

   Using the FIPS module in SSL/TLS
       Writing  an application that uses libssl in conjunction with the FIPS module is much the same
       as writing a normal libssl application. If you are using global properties  and  the  default
       library  context  to  specify  usage  of  FIPS  validated  algorithms  then  this will happen
       automatically for all cryptographic algorithms in libssl.  If  you  are  using  a  nondefault
       library  context  to  load  the  FIPS  provider  then you can supply this to libssl using the
       function  SSL_CTX_new_ex(3).  This  works  as  a  drop  in  replacement  for   the   function
       SSL_CTX_new(3)  except  it provides you with the capability to specify the library context to
       be used. You can also use the same function to specify libssl specific properties to use.

       In this first example we create two SSL_CTX objects using two different library contexts.

           /*
            * We assume that a nondefault library context with the FIPS
            * provider loaded has been created called fips_libctx.
            */
           SSL_CTX *fips_ssl_ctx = SSL_CTX_new_ex(fips_libctx, NULL, TLS_method());
           /*
            * We assume that a nondefault library context with the default
            * provider loaded has been created called non_fips_libctx.
            */
           SSL_CTX *non_fips_ssl_ctx = SSL_CTX_new_ex(non_fips_libctx, NULL,
                                                      TLS_method());

       In this second example we create two SSL_CTX objects using different  properties  to  specify
       FIPS usage:

           /*
            * The "fips=yes" property includes all FIPS approved algorithms
            * as well as encoders from the default provider that are allowed
            * to be used. The NULL below indicates that we are using the
            * default library context.
            */
           SSL_CTX *fips_ssl_ctx = SSL_CTX_new_ex(NULL, "fips=yes", TLS_method());
           /*
            * The "provider!=fips" property allows algorithms from any
            * provider except the FIPS provider
            */
           SSL_CTX *non_fips_ssl_ctx = SSL_CTX_new_ex(NULL, "provider!=fips",
                                                      TLS_method());

   Confirming that an algorithm is being provided by the FIPS module
       A  chain  of links needs to be followed to go from an algorithm instance to the provider that
       implements it. The process is similar for all algorithms. Here the example  of  a  digest  is
       used.

       To  go  from an EVP_MD_CTX to an EVP_MD, use EVP_MD_CTX_md(3) .  To go from the EVP_MD to its
       OSSL_PROVIDER, use EVP_MD_get0_provider(3).  To extract the name from the OSSL_PROVIDER,  use
       OSSL_PROVIDER_get0_name(3).

NOTES
       Some  released  versions  of  OpenSSL do not include a validated FIPS provider.  To determine
       which versions have undergone the validation process, please refer to the  OpenSSL  Downloads
       page  <https://www.openssl.org/source/>.   If  you require FIPS-approved functionality, it is
       essential to build your FIPS provider using one  of  the  validated  versions  listed  there.
       Normally,  it  is  possible  to utilize a FIPS provider constructed from one of the validated
       versions alongside libcrypto and libssl compiled from  any  release  within  the  same  major
       release series.  This flexibility enables you to address bug fixes and CVEs that fall outside
       the FIPS boundary.

SEE ALSO
       migration_guide(7), crypto(7), fips_config(5), <https://www.openssl.org/source/>

HISTORY
       The FIPS module guide was created for use with the new FIPS provider in OpenSSL 3.0.

COPYRIGHT
       Copyright 2021-2023 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 <https://www.openssl.org/source/license.html>.

3.0.13                                       2026-07-29                            FIPS_MODULE(7SSL)