1Providers 2========= 3 4 - [Standard Providers](#standard-providers) 5 - [The Default Provider](#the-default-provider) 6 - [The Legacy Provider](#the-legacy-provider) 7 - [The FIPS Provider](#the-fips-provider) 8 - [The Base Provider](#the-base-provider) 9 - [The Null Provider](#the-null-provider) 10 - [Loading Providers](#loading-providers) 11 12Standard Providers 13================== 14 15Providers are containers for algorithm implementations. Whenever a cryptographic 16algorithm is used via the high level APIs a provider is selected. It is that 17provider implementation that actually does the required work. There are five 18providers distributed with OpenSSL. In the future, we expect third parties to 19distribute their own providers which can be added to OpenSSL dynamically. 20Documentation about writing providers is available on the [provider(7)] 21manual page. 22 23 [provider(7)]: https://www.openssl.org/docs/manmaster/man7/provider.html 24 25The Default Provider 26-------------------- 27 28The default provider collects together all of the standard built-in OpenSSL 29algorithm implementations. If an application doesn't specify anything else 30explicitly (e.g. in the application or via config), then this is the provider 31that will be used. It is loaded automatically the first time that we try to 32get an algorithm from a provider if no other provider has been loaded yet. 33If another provider has already been loaded then it won't be loaded 34automatically. Therefore, if you want to use it in conjunction with other 35providers, then you must load it explicitly. 36 37This is a "built-in" provider, which means that it is compiled and linked 38into the libcrypto library and does not exist as a separate standalone module. 39 40The Legacy Provider 41------------------- 42 43The legacy provider is a collection of legacy algorithms that are either no 44longer in common use or considered insecure and strongly discouraged from use. 45However, some applications may need to use these algorithms for backwards 46compatibility reasons. This provider is **not** loaded by default. 47This may mean that some applications upgrading from earlier versions of OpenSSL 48may find that some algorithms are no longer available unless they load the 49legacy provider explicitly. 50 51Algorithms in the legacy provider include MD2, MD4, MDC2, RMD160, CAST5, 52BF (Blowfish), IDEA, SEED, RC2, RC4, RC5 and DES (but not 3DES). 53 54The FIPS Provider 55----------------- 56 57The FIPS provider contains a sub-set of the algorithm implementations available 58from the default provider, consisting of algorithms conforming to FIPS standards. 59It is intended that this provider will be FIPS140-2 validated. 60 61In some cases, there may be minor behavioural differences between algorithm 62implementations in this provider compared to the equivalent algorithm in the 63default provider. This is typically in order to conform to FIPS standards. 64 65The Base Provider 66----------------- 67 68The base provider contains a small sub-set of non-cryptographic algorithms 69available in the default provider. For example, it contains algorithms to 70serialize and deserialize keys to files. If you do not load the default 71provider then you should always load this one instead (in particular, if 72you are using the FIPS provider). 73 74The Null Provider 75----------------- 76 77The null provider is "built-in" to libcrypto and contains no algorithm 78implementations. In order to guarantee that the default provider is not 79automatically loaded, the null provider can be loaded instead. 80 81This can be useful if you are using non-default library contexts and want 82to ensure that the default library context is never used unintentionally. 83 84Loading Providers 85================= 86 87Providers to be loaded can be specified in the OpenSSL config file. 88See the [config(5)] manual page for information about how to configure 89providers via the config file, and how to automatically activate them. 90 91 [config(5)]: https://www.openssl.org/docs/manmaster/man5/config.html 92 93The following is a minimal config file example to load and activate both 94the legacy and the default provider in the default library context. 95 96 openssl_conf = openssl_init 97 98 [openssl_init] 99 providers = provider_sect 100 101 [provider_sect] 102 default = default_sect 103 legacy = legacy_sect 104 105 [default_sect] 106 activate = 1 107 108 [legacy_sect] 109 activate = 1 110 111It is also possible to load providers programmatically. For example you can 112load the legacy provider into the default library context as shown below. 113Note that once you have explicitly loaded a provider into the library context 114the default provider will no longer be automatically loaded. Therefore you will 115often also want to explicitly load the default provider, as is done here: 116 117 #include <stdio.h> 118 #include <stdlib.h> 119 120 #include <openssl/provider.h> 121 122 int main(void) 123 { 124 OSSL_PROVIDER *legacy; 125 OSSL_PROVIDER *deflt; 126 127 /* Load Multiple providers into the default (NULL) library context */ 128 legacy = OSSL_PROVIDER_load(NULL, "legacy"); 129 if (legacy == NULL) { 130 printf("Failed to load Legacy provider\n"); 131 exit(EXIT_FAILURE); 132 } 133 deflt = OSSL_PROVIDER_load(NULL, "default"); 134 if (deflt == NULL) { 135 printf("Failed to load Default provider\n"); 136 OSSL_PROVIDER_unload(legacy); 137 exit(EXIT_FAILURE); 138 } 139 140 /* Rest of application */ 141 142 OSSL_PROVIDER_unload(legacy); 143 OSSL_PROVIDER_unload(deflt); 144 exit(EXIT_SUCCESS); 145 } 146
