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 ossl-guide-migration(7)
    for a list of deprecated functions.

  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
        alg_section = algorithm_sect

        [provider_sect]
        fips = fips_sect
        base = base_sect

        [base_sect]
        activate = 1

        [algorithm_sect]
        default_properties = fips=yes

    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
    unspecified 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 unspecified 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;

        /*
         * Set the default property query on the FIPS library context to
         * ensure that only FIPS algorithms can be used.  There are a few non-FIPS
         * approved algorithms in the FIPS provider for backward compatibility reasons.
         */
        if (!EVP_set_default_properties(fips_libctx, "fips=yes"))
            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 ossl-guide-migration(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, "fips=yes", 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).

  FIPS indicators
    FIPS indicators have been added to the FIPS provider in OpenSSL 3.4.
    FIPS 140-3 requires indicators to be used if the FIPS provider allows
    non approved algorithms. An algorithm is approved if it passes all
    required checks such as minimum key size. By default an error will occur
    if any check fails. For backwards compatibility individual algorithms
    may override the checks by using either an option in the FIPS
    configuration (See "FIPS indicator options" in fips_config(5)) OR in
    code using an algorithm context setter. Overriding the check means that
    the algorithm is not FIPS compliant. OSSL_INDICATOR_set_callback(3) can
    be called to register a callback to log unapproved algorithms. At the
    end of any algorithm operation the approved status can be queried using
    an algorithm context getter to retrieve the indicator (e.g.
    "fips-indicator"). An example of an algorithm context setter is
    "key-check" in "Supported parameters" in EVP_KDF-HKDF(7).

    The following algorithms use "fips-indicator" to query if the algorithm
    is approved:

    DSA Key generation
        DSA Key generation is no longer approved. See "DSA parameters" in
        EVP_PKEY-DSA(7)

    DSA Signatures
        DSA Signature generation is no longer approved. See "Signature
        Parameters" in EVP_SIGNATURE-DSA(7)

    ECDSA Signatures
        See "ECDSA Signature Parameters" in EVP_SIGNATURE-ECDSA(7)

    EC Key Generation
        See "Common EC parameters" in EVP_PKEY-EC(7)

    RSA Encryption
        "pkcs1" padding is no longer approved.

        See "RSA Asymmetric Cipher parameters" in EVP_ASYM_CIPHER-RSA(7) and
        "RSA KEM parameters" in EVP_KEM-RSA(7)

    RSA Signatures
        See "Signature Parameters" in EVP_SIGNATURE-RSA(7)

    DRBGS
        See "Supported parameters" in EVP_RAND-HASH-DRBG(7) and
        EVP_RAND-HMAC-DRBG(7)/Supported parameters>

    DES Triple-DES is not longer approved for encryption. See "Parameters"
        in EVP_CIPHER-DES(7)

    DH  See "DH and DHX key exchange parameters" in EVP_KEYEXCH-DH(7)

    ECDH
        See "ECDH Key Exchange parameters" in EVP_KEYEXCH-ECDH(7)

    KDFS
        See relevant KDF documentation e.g. "Supported parameters" in
        EVP_KDF-HKDF(7)

    CMAC and KMAC
        See "Supported parameters" in EVP_MAC-CMAC(7) and "Supported
        parameters" in EVP_MAC-KMAC(7)

    The following FIPS algorithms are unapproved and use the
    "fips-indicator".

    RAND-TEST-RAND
        See "Supported parameters" in EVP_RAND-TEST-RAND(7) The indicator
        callback is NOT triggered for this algorithm since it is used
        internally for non security purposes.

    X25519 and X448 Key Generation and Key Exchange

    The unapproved (non FIPS validated) algorithms have a property query
    value of "fips=no".

    The following algorithms use a unique indicator and do not trigger the
    indicator callback.

    AES-GCM ciphers support the indicator "iv-generated"
        See "PARAMETERS" in EVP_EncryptInit(3) for further information.

    ECDSA and RSA Signatures support the indicator "verify-message".
        See "ECDSA Signature Parameters" in EVP_SIGNATURE-ECDSA(7) and
        "Signature Parameters" in EVP_SIGNATURE-RSA(7) /for further
        information.

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.

    As the FIPS provider still supports non-FIPS validated algorithms, The
    property query "fips=yes" is mandatory for applications that want to
    operate in a FIPS approved manner.

SEE ALSO
    ossl-guide-migration(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. FIPS indicators were added in OpenSSL 3.4.

COPYRIGHT
    Copyright 2021-2025 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>.

