FIPS_MODULE(7ossl) OpenSSL FIPS_MODULE(7ossl)
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:
o Low level cryptographic APIs (use the high level APIs, such as EVP,
instead)
o Engines
o 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:
o 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.
o If applications take explicit steps to not load the default config
file or set different settings.
This method will not work for these cases.
o 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.
o 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).
Every algorithm implementation advertised with the property "fips=yes" by
the OpenSSL FIPS provider exposes "fips-indicator" as a gettable context
parameter. The getter returns 1 when the operation is approved. An
absent indicator must not be interpreted as approval.
Algorithms advertised with "fips=no" are unapproved. When such an
implementation exposes "fips-indicator", its getter returns 0. Providers
other than the OpenSSL FIPS provider are not required to expose this
parameter; an absent indicator, or an indicator value of 0, does not
assert FIPS approval.
Some algorithms can change from approved to unapproved as a result of
their parameters or the operation performed. The following algorithms
perform such additional checks:
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)
ML-KEM Key Encapsulation
Supplying the test-only "ikme" parameter makes the operation
unapproved. See "ML-KEM KEM parameters" in EVP_KEM-ML-KEM(7).
ML-DSA and SLH-DSA Signatures
Supplying test entropy makes the operation unapproved. ML-DSA
operations that disable the standard message encoding are also
unapproved. See "FIPS indicator" in EVP_SIGNATURE-ML-DSA(7) and
"FIPS indicator" in EVP_SIGNATURE-SLH-DSA(7).
RSA Key Generation
Supplying the parameters reserved for FIPS module testing makes the
operation unapproved. See "RSA key generation FIPS indicator" in
EVP_PKEY-RSA(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
X448MLKEM1024 Key Generation and Key Encapsulation
The other hybrid ML-KEM algorithms supplied by the FIPS provider are
approved, including X25519MLKEM768, SecP256r1MLKEM768 and
SecP384r1MLKEM1024.
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. The
AES-GCM "fips-indicator" also accounts for the IV source and returns
0 after encryption with an externally supplied IV. It also returns 0
for GCM tag lengths other than 4, 8, or 12 through 16 bytes.
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. The signature "fips-indicator" also accounts for this
value and returns 0 when verification is performed directly on a
caller-supplied digest.
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://openssl-
library.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 supported release from OpenSSL 3.0 onwards;
provider compatibility is maintained backward and forward across these
releases, including future major release series, for as long as the
module remains supported. 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 2021-2026 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>.
3.6.5 2026-09-29 FIPS_MODULE(7ossl)
openssl 3.6.5 - Generated Sat Oct 3 11:41:03 CDT 2026