1FIPS_MODULE(7ossl) OpenSSL FIPS_MODULE(7ossl)
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6 fips_module - OpenSSL fips module guide
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9 See the individual manual pages for details.
10
12 This guide details different ways that OpenSSL can be used in
13 conjunction with the FIPS module. Which is the correct approach to use
14 will depend on your own specific circumstances and what you are
15 attempting to achieve.
16 Note that the old functions FIPS_mode() and FIPS_mode_set() are no
18 longer present so you must remove them from your application if you use
19 them.
20 Applications written to use the OpenSSL 3.0 FIPS module should not use
22 any legacy APIs or features that avoid the FIPS module. Specifically
23 this includes:
24 • Low level cryptographic APIs (use the high level APIs, such as EVP,
26 instead)
27 • Engines
29 • Any functions that create or modify custom "METHODS" (for example
31 EVP_MD_meth_new(), EVP_CIPHER_meth_new(), EVP_PKEY_meth_new(),
32 RSA_meth_new(), EC_KEY_METHOD_new(), etc.)
33 All of the above APIs are deprecated in OpenSSL 3.0 - so a simple rule
35 is to avoid using all deprecated functions. See migration_guide(7) for
36 a list of deprecated functions.
37 Making all applications use the FIPS module by default
39 One simple approach is to cause all applications that are using OpenSSL
40 to only use the FIPS module for cryptographic algorithms by default.
41 This approach can be done purely via configuration. As long as
43 applications are built and linked against OpenSSL 3.0 and do not
44 override the loading of the default config file or its settings then
45 they can automatically start using the FIPS module without the need for
46 any further code changes.
47 To do this the default OpenSSL config file will have to be modified.
49 The location of this config file will depend on the platform, and any
50 options that were given during the build process. You can check the
51 location of the config file by running this command:
52 $ openssl version -d
54 OPENSSLDIR: "/usr/local/ssl"
55 Caution: Many Operating Systems install OpenSSL by default. It is a
57 common error to not have the correct version of OpenSSL in your $PATH.
58 Check that you are running an OpenSSL 3.0 version like this:
59 $ openssl version -v
61 OpenSSL 3.0.0-dev xx XXX xxxx (Library: OpenSSL 3.0.0-dev xx XXX xxxx)
62 The OPENSSLDIR value above gives the directory name for where the
64 default config file is stored. So in this case the default config file
65 will be called /usr/local/ssl/openssl.cnf.
66 Edit the config file to add the following lines near the beginning:
68 config_diagnostics = 1
70 openssl_conf = openssl_init
71 .include /usr/local/ssl/fipsmodule.cnf
73 [openssl_init]
75 providers = provider_sect
76 [provider_sect]
78 fips = fips_sect
79 base = base_sect
80 [base_sect]
82 activate = 1
83 Obviously the include file location above should match the path and
85 name of the FIPS module config file that you installed earlier. See
86 <https://github.com/openssl/openssl/blob/master/README-FIPS.md>.
87 For FIPS usage, it is recommened that the config_diagnostics option is
89 enabled to prevent accidental use of non-FIPS validated algorithms via
90 broken or mistaken configuration. See config(5).
91 Any applications that use OpenSSL 3.0 and are started after these
93 changes are made will start using only the FIPS module unless those
94 applications take explicit steps to avoid this default behaviour. Note
95 that this configuration also activates the "base" provider. The base
96 provider does not include any cryptographic algorithms (and therefore
97 does not impact the validation status of any cryptographic operations),
98 but does include other supporting algorithms that may be required. It
99 is designed to be used in conjunction with the FIPS module.
100 This approach has the primary advantage that it is simple, and no code
102 changes are required in applications in order to benefit from the FIPS
103 module. There are some disadvantages to this approach:
104 • You may not want all applications to use the FIPS module.
106 It may be the case that some applications should and some should
108 not use the FIPS module.
109 • If applications take explicit steps to not load the default config
111 file or set different settings.
112 This method will not work for these cases.
114 • The algorithms available in the FIPS module are a subset of the
116 algorithms that are available in the default OpenSSL Provider.
117 If any applications attempt to use any algorithms that are not
119 present, then they will fail.
120 • Usage of certain deprecated APIs avoids the use of the FIPS module.
122 If any applications use those APIs then the FIPS module will not be
124 used.
125 Selectively making applications use the FIPS module by default
127 A variation on the above approach is to do the same thing on an
128 individual application basis. The default OpenSSL config file depends
129 on the compiled in value for OPENSSLDIR as described in the section
130 above. However it is also possible to override the config file to be
131 used via the OPENSSL_CONF environment variable. For example the
132 following, on Unix, will cause the application to be executed with a
133 non-standard config file location:
134 $ OPENSSL_CONF=/my/nondefault/openssl.cnf myapplication
136 Using this mechanism you can control which config file is loaded (and
138 hence whether the FIPS module is loaded) on an application by
139 application basis.
140 This removes the disadvantage listed above that you may not want all
142 applications to use the FIPS module. All the other advantages and
143 disadvantages still apply.
144 Programmatically loading the FIPS module (default library context)
146 Applications may choose to load the FIPS provider explicitly rather
147 than relying on config to do this. The config file is still necessary
148 in order to hold the FIPS module config data (such as its self test
149 status and integrity data). But in this case we do not automatically
150 activate the FIPS provider via that config file.
151 To do things this way configure as per "Making all applications use the
153 FIPS module by default" above, but edit the fipsmodule.cnf file to
154 remove or comment out the line which says "activate = 1" (note that
155 setting this value to 0 is not sufficient). This means all the
156 required config information will be available to load the FIPS module,
157 but it is not automatically loaded when the application starts. The
158 FIPS provider can then be loaded programmatically like this:
159 #include <openssl/provider.h>
161 int main(void)
163 {
164 OSSL_PROVIDER *fips;
165 OSSL_PROVIDER *base;
166 fips = OSSL_PROVIDER_load(NULL, "fips");
168 if (fips == NULL) {
169 printf("Failed to load FIPS provider\n");
170 exit(EXIT_FAILURE);
171 }
172 base = OSSL_PROVIDER_load(NULL, "base");
173 if (base == NULL) {
174 OSSL_PROVIDER_unload(fips);
175 printf("Failed to load base provider\n");
176 exit(EXIT_FAILURE);
177 }
178 /* Rest of application */
180 OSSL_PROVIDER_unload(base);
182 OSSL_PROVIDER_unload(fips);
183 exit(EXIT_SUCCESS);
184 }
185 Note that this should be one of the first things that you do in your
187 application. If any OpenSSL functions get called that require the use
188 of cryptographic functions before this occurs then, if no provider has
189 yet been loaded, then the default provider will be automatically
190 loaded. If you then later explicitly load the FIPS provider then you
191 will have both the FIPS and the default provider loaded at the same
192 time. It is undefined which implementation of an algorithm will be used
193 if multiple implementations are available and you have not explicitly
194 specified via a property query (see below) which one should be used.
195 Also note that in this example we have additionally loaded the "base"
197 provider. This loads a sub-set of algorithms that are also available
198 in the default provider - specifically non cryptographic ones which may
199 be used in conjunction with the FIPS provider. For example this
200 contains algorithms for encoding and decoding keys. If you decide not
201 to load the default provider then you will usually want to load the
202 base provider instead.
203 In this example we are using the "default" library context. OpenSSL
205 functions operate within the scope of a library context. If no library
206 context is explicitly specified then the default library context is
207 used. For further details about library contexts see the
208 OSSL_LIB_CTX(3) man page.
209 Loading the FIPS module at the same time as other providers
211 It is possible to have the FIPS provider and other providers (such as
212 the default provider) all loaded at the same time into the same library
213 context. You can use a property query string during algorithm fetches
214 to specify which implementation you would like to use.
215 For example to fetch an implementation of SHA256 which conforms to FIPS
217 standards you can specify the property query "fips=yes" like this:
218 EVP_MD *sha256;
220 sha256 = EVP_MD_fetch(NULL, "SHA2-256", "fips=yes");
222 If no property query is specified, or more than one implementation
224 matches the property query then it is undefined which implementation of
225 a particular algorithm will be returned.
226 This example shows an explicit request for an implementation of SHA256
228 from the default provider:
229 EVP_MD *sha256;
231 sha256 = EVP_MD_fetch(NULL, "SHA2-256", "provider=default");
233 It is also possible to set a default property query string. The
235 following example sets the default property query of "fips=yes" for all
236 fetches within the default library context:
237 EVP_set_default_properties(NULL, "fips=yes");
239 If a fetch function has both an explicit property query specified, and
241 a default property query is defined then the two queries are merged
242 together and both apply. The local property query overrides the default
243 properties if the same property name is specified in both.
244 There are two important built-in properties that you should be aware
246 of:
247 The "provider" property enables you to specify which provider you want
249 an implementation to be fetched from, e.g. "provider=default" or
250 "provider=fips". All algorithms implemented in a provider have this
251 property set on them.
252 There is also the "fips" property. All FIPS algorithms match against
254 the property query "fips=yes". There are also some non-cryptographic
255 algorithms available in the default and base providers that also have
256 the "fips=yes" property defined for them. These are the encoder and
257 decoder algorithms that can (for example) be used to write out a key
258 generated in the FIPS provider to a file. The encoder and decoder
259 algorithms are not in the FIPS module itself but are allowed to be used
260 in conjunction with the FIPS algorithms.
261 It is possible to specify default properties within a config file. For
263 example the following config file automatically loads the default and
264 FIPS providers and sets the default property value to be "fips=yes".
265 Note that this config file does not load the "base" provider. All
266 supporting algorithms that are in "base" are also in "default", so it
267 is unnecessary in this case:
268 config_diagnostics = 1
270 openssl_conf = openssl_init
271 .include /usr/local/ssl/fipsmodule.cnf
273 [openssl_init]
275 providers = provider_sect
276 alg_section = algorithm_sect
277 [provider_sect]
279 fips = fips_sect
280 default = default_sect
281 [default_sect]
283 activate = 1
284 [algorithm_sect]
286 default_properties = fips=yes
287 Programmatically loading the FIPS module (nondefault library context)
289 In addition to using properties to separate usage of the FIPS module
290 from other usages this can also be achieved using library contexts. In
291 this example we create two library contexts. In one we assume the
292 existence of a config file called openssl-fips.cnf that automatically
293 loads and configures the FIPS and base providers. The other library
294 context will just use the default provider.
295 OSSL_LIB_CTX *fips_libctx, *nonfips_libctx;
297 OSSL_PROVIDER *defctxnull = NULL;
298 EVP_MD *fipssha256 = NULL, *nonfipssha256 = NULL;
299 int ret = 1;
300 /*
302 * Create two nondefault library contexts. One for fips usage and
303 * one for non-fips usage
304 */
305 fips_libctx = OSSL_LIB_CTX_new();
306 nonfips_libctx = OSSL_LIB_CTX_new();
307 if (fips_libctx == NULL || nonfips_libctx == NULL)
308 goto err;
309 /* Prevent anything from using the default library context */
311 defctxnull = OSSL_PROVIDER_load(NULL, "null");
312 /*
314 * Load config file for the FIPS library context. We assume that
315 * this config file will automatically activate the FIPS and base
316 * providers so we don't need to explicitly load them here.
317 */
318 if (!OSSL_LIB_CTX_load_config(fips_libctx, "openssl-fips.cnf"))
319 goto err;
320 /*
322 * We don't need to do anything special to load the default
323 * provider into nonfips_libctx. This happens automatically if no
324 * other providers are loaded.
325 * Because we don't call OSSL_LIB_CTX_load_config() explicitly for
326 * nonfips_libctx it will just use the default config file.
327 */
328 /* As an example get some digests */
330 /* Get a FIPS validated digest */
332 fipssha256 = EVP_MD_fetch(fips_libctx, "SHA2-256", NULL);
333 if (fipssha256 == NULL)
334 goto err;
335 /* Get a non-FIPS validated digest */
337 nonfipssha256 = EVP_MD_fetch(nonfips_libctx, "SHA2-256", NULL);
338 if (nonfipssha256 == NULL)
339 goto err;
340 /* Use the digests */
342 printf("Success\n");
344 ret = 0;
345 err:
347 EVP_MD_free(fipssha256);
348 EVP_MD_free(nonfipssha256);
349 OSSL_LIB_CTX_free(fips_libctx);
350 OSSL_LIB_CTX_free(nonfips_libctx);
351 OSSL_PROVIDER_unload(defctxnull);
352 return ret;
354 Note that we have made use of the special "null" provider here which we
356 load into the default library context. We could have chosen to use the
357 default library context for FIPS usage, and just create one additional
358 library context for other usages - or vice versa. However if code has
359 not been converted to use library contexts then the default library
360 context will be automatically used. This could be the case for your
361 own existing applications as well as certain parts of OpenSSL itself.
362 Not all parts of OpenSSL are library context aware. If this happens
363 then you could "accidentally" use the wrong library context for a
364 particular operation. To be sure this doesn't happen you can load the
365 "null" provider into the default library context. Because a provider
366 has been explicitly loaded, the default provider will not automatically
367 load. This means code using the default context by accident will fail
368 because no algorithms will be available.
369 See "Library Context" in migration_guide(7) for additional information
371 about the Library Context.
372 Using Encoders and Decoders with the FIPS module
374 Encoders and decoders are used to read and write keys or parameters
375 from or to some external format (for example a PEM file). If your
376 application generates keys or parameters that then need to be written
377 into PEM or DER format then it is likely that you will need to use an
378 encoder to do this. Similarly you need a decoder to read previously
379 saved keys and parameters. In most cases this will be invisible to you
380 if you are using APIs that existed in OpenSSL 1.1.1 or earlier such as
381 i2d_PrivateKey(3). However the appropriate encoder/decoder will need to
382 be available in the library context associated with the key or
383 parameter object. The built-in OpenSSL encoders and decoders are
384 implemented in both the default and base providers and are not in the
385 FIPS module boundary. However since they are not cryptographic
386 algorithms themselves it is still possible to use them in conjunction
387 with the FIPS module, and therefore these encoders/decoders have the
388 "fips=yes" property against them. You should ensure that either the
389 default or base provider is loaded into the library context in this
390 case.
391 Using the FIPS module in SSL/TLS
393 Writing an application that uses libssl in conjunction with the FIPS
394 module is much the same as writing a normal libssl application. If you
395 are using global properties and the default library context to specify
396 usage of FIPS validated algorithms then this will happen automatically
397 for all cryptographic algorithms in libssl. If you are using a
398 nondefault library context to load the FIPS provider then you can
399 supply this to libssl using the function SSL_CTX_new_ex(3). This works
400 as a drop in replacement for the function SSL_CTX_new(3) except it
401 provides you with the capability to specify the library context to be
402 used. You can also use the same function to specify libssl specific
403 properties to use.
404 In this first example we create two SSL_CTX objects using two different
406 library contexts.
407 /*
409 * We assume that a nondefault library context with the FIPS
410 * provider loaded has been created called fips_libctx.
411 */
412 SSL_CTX *fips_ssl_ctx = SSL_CTX_new_ex(fips_libctx, NULL, TLS_method());
413 /*
414 * We assume that a nondefault library context with the default
415 * provider loaded has been created called non_fips_libctx.
416 */
417 SSL_CTX *non_fips_ssl_ctx = SSL_CTX_new_ex(non_fips_libctx, NULL,
418 TLS_method());
419 In this second example we create two SSL_CTX objects using different
421 properties to specify FIPS usage:
422 /*
424 * The "fips=yes" property includes all FIPS approved algorithms
425 * as well as encoders from the default provider that are allowed
426 * to be used. The NULL below indicates that we are using the
427 * default library context.
428 */
429 SSL_CTX *fips_ssl_ctx = SSL_CTX_new_ex(NULL, "fips=yes", TLS_method());
430 /*
431 * The "provider!=fips" property allows algorithms from any
432 * provider except the FIPS provider
433 */
434 SSL_CTX *non_fips_ssl_ctx = SSL_CTX_new_ex(NULL, "provider!=fips",
435 TLS_method());
436 Confirming that an algorithm is being provided by the FIPS module
438 A chain of links needs to be followed to go from an algorithm instance
439 to the provider that implements it. The process is similar for all
440 algorithms. Here the example of a digest is used.
441 To go from an EVP_MD_CTX to an EVP_MD, use EVP_MD_CTX_md(3) . To go
443 from the EVP_MD to its OSSL_PROVIDER, use EVP_MD_get0_provider(3). To
444 extract the name from the OSSL_PROVIDER, use
445 OSSL_PROVIDER_get0_name(3).
446
448 migration_guide(7), crypto(7), fips_config(5)
449
451 Copyright 2021-2022 The OpenSSL Project Authors. All Rights Reserved.
452 Licensed under the Apache License 2.0 (the "License"). You may not use
454 this file except in compliance with the License. You can obtain a copy
455 in the file LICENSE in the source distribution or at
456 <https://www.openssl.org/source/license.html>.
4573.0.5 2022-07-05 FIPS_MODULE(7ossl)