=pod =head1 NAME migration_guide - OpenSSL migration guide =head1 SYNOPSIS See the individual manual pages for details. =head1 DESCRIPTION This guide details the changes required to migrate to new versions of OpenSSL. Currently this covers OpenSSL 3.0. For earlier versions refer to L. For an overview of some of the key concepts introduced in OpenSSL 3.0 see L. =head1 OPENSSL 3.0 =head2 Main Changes from OpenSSL 1.1.1 =head3 Major Release OpenSSL 3.0 is a major release and consequently any application that currently uses an older version of OpenSSL will at the very least need to be recompiled in order to work with the new version. It is the intention that the large majority of applications will work unchanged with OpenSSL 3.0 if those applications previously worked with OpenSSL 1.1.1. However this is not guaranteed and some changes may be required in some cases. Changes may also be required if applications need to take advantage of some of the new features available in OpenSSL 3.0 such as the availability of the FIPS module. =head3 License Change In previous versions, OpenSSL was licensed under the L (both licenses apply). From OpenSSL 3.0 this is replaced by the L. =head3 Providers and FIPS support One of the key changes from OpenSSL 1.1.1 is the introduction of the Provider concept. Providers collect together and make available algorithm implementations. With OpenSSL 3.0 it is possible to specify, either programmatically or via a config file, which providers you want to use for any given application. OpenSSL 3.0 comes with 5 different providers as standard. Over time third parties may distribute additional providers that can be plugged into OpenSSL. All algorithm implementations available via providers are accessed through the "high level" APIs (for example those functions prefixed with C). They cannot be accessed using the L. One of the standard providers available is the FIPS provider. This makes available FIPS validated cryptographic algorithms. The FIPS provider is disabled by default and needs to be enabled explicitly at configuration time using the C option. If it is enabled, the FIPS provider gets built and installed in addition to the other standard providers. No separate installation procedure is necessary. There is however a dedicated C make target, which serves the special purpose of installing only the FIPS provider into an existing OpenSSL installation. Not all algorithms may be available for the application at a particular moment. If the application code uses any digest or cipher algorithm via the EVP interface, the application should verify the result of the L, L, and L functions. In case when the requested algorithm is not available, these functions will fail. See also L for information on the legacy provider. See also L and L. =head3 Low Level APIs OpenSSL has historically provided two sets of APIs for invoking cryptographic algorithms: the "high level" APIs (such as the C APIs) and the "low level" APIs. The high level APIs are typically designed to work across all algorithm types. The "low level" APIs are targeted at a specific algorithm implementation. For example, the EVP APIs provide the functions L, L and L to perform symmetric encryption. Those functions can be used with the algorithms AES, CHACHA, 3DES etc. On the other hand, to do AES encryption using the low level APIs you would have to call AES specific functions such as L, L, and so on. The functions for 3DES are different. Use of the low level APIs has been informally discouraged by the OpenSSL development team for a long time. However in OpenSSL 3.0 this is made more formal. All such low level APIs have been deprecated. You may still use them in your applications, but you may start to see deprecation warnings during compilation (dependent on compiler support for this). Deprecated APIs may be removed from future versions of OpenSSL so you are strongly encouraged to update your code to use the high level APIs instead. This is described in more detail in L =head3 Legacy Algorithms Some cryptographic algorithms such as B and B that were available via the EVP APIs are now considered legacy and their use is strongly discouraged. These legacy EVP algorithms are still available in OpenSSL 3.0 but not by default. If you want to use them then you must load the legacy provider. This can be as simple as a config file change, or can be done programmatically. See L for a complete list of algorithms. Applications using the EVP APIs to access these algorithms should instead use more modern algorithms. If that is not possible then these applications should ensure that the legacy provider has been loaded. This can be achieved either programmatically or via configuration. See L man page for more information about providers. =head3 Engines and "METHOD" APIs The refactoring to support Providers conflicts internally with the APIs used to support engines, including the ENGINE API and any function that creates or modifies custom "METHODS" (for example L, L, L, L, L, etc.). These functions are being deprecated in OpenSSL 3.0, and users of these APIs should know that their use can likely bypass provider selection and configuration, with unintended consequences. This is particularly relevant for applications written to use the OpenSSL 3.0 FIPS module, as detailed below. Authors and maintainers of external engines are strongly encouraged to refactor their code transforming engines into providers using the new Provider API and avoiding deprecated methods. =head3 Support of legacy engines If openssl is not built without engine support or deprecated API support, engines will still work. However, their applicability will be limited. New algorithms provided via engines will still work. Engine-backed keys can be loaded via custom B implementation. In this case the B objects created via L will be considered legacy and will continue to work. To ensure the future compatibility, the engines should be turned to providers. To prefer the provider-based hardware offload, you can specify the default properties to prefer your provider. =head3 Versioning Scheme The OpenSSL versioning scheme has changed with the OpenSSL 3.0 release. The new versioning scheme has this format: MAJOR.MINOR.PATCH For OpenSSL 1.1.1 and below, different patch levels were indicated by a letter at the end of the release version number. This will no longer be used and instead the patch level is indicated by the final number in the version. A change in the second (MINOR) number indicates that new features may have been added. OpenSSL versions with the same major number are API and ABI compatible. If the major number changes then API and ABI compatibility is not guaranteed. For more information, see L. =head3 Other major new features =head4 Certificate Management Protocol (CMP, RFC 4210) This also covers CRMF (RFC 4211) and HTTP transfer (RFC 6712) See L and L as starting points. =head4 HTTP(S) client A proper HTTP(S) client that supports GET and POST, redirection, plain and ASN.1-encoded contents, proxies, and timeouts. =head4 Key Derivation Function API (EVP_KDF) This simplifies the process of adding new KDF and PRF implementations. Previously KDF algorithms had been shoe-horned into using the EVP_PKEY object which was not a logical mapping. Existing applications that use KDF algorithms using EVP_PKEY (scrypt, TLS1 PRF and HKDF) may be slower as they use an EVP_KDF bridge internally. All new applications should use the new L interface. See also L and L. =head4 Message Authentication Code API (EVP_MAC) This simplifies the process of adding MAC implementations. This includes a generic EVP_PKEY to EVP_MAC bridge, to facilitate the continued use of MACs through raw private keys in functionality such as L and L. All new applications should use the new L interface. See also L and L. =head4 Algorithm Fetching Using calls to convenience functions such as EVP_sha256() and EVP_aes_256_gcm() may incur a performance penalty when using providers. Retrieving algorithms from providers involves searching for an algorithm by name. This is much slower than directly accessing a method table. It is recommended to prefetch algorithms if an algorithm is used many times. See L, L and L. =head4 Support for Linux Kernel TLS In order to use KTLS, support for it must be compiled in using the C configuration option. It must also be enabled at run time using the B option. =head4 New Algorithms =over 4 =item * KDF algorithms "SINGLE STEP" and "SSH" See L and L =item * MAC Algorithms "GMAC" and "KMAC" See L and L. =item * KEM Algorithm "RSASVE" See L. =item * Cipher Algorithm "AES-SIV" See L. =item * AES Key Wrap inverse ciphers supported by EVP layer. The inverse ciphers use AES decryption for wrapping, and AES encryption for unwrapping. The algorithms are: "AES-128-WRAP-INV", "AES-192-WRAP-INV", "AES-256-WRAP-INV", "AES-128-WRAP-PAD-INV", "AES-192-WRAP-PAD-INV" and "AES-256-WRAP-PAD-INV". =item * CTS ciphers added to EVP layer. The algorithms are "AES-128-CBC-CTS", "AES-192-CBC-CTS", "AES-256-CBC-CTS", "CAMELLIA-128-CBC-CTS", "CAMELLIA-192-CBC-CTS" and "CAMELLIA-256-CBC-CTS". CS1, CS2 and CS3 variants are supported. =back =head4 CMS and PKCS#7 updates =over 4 =item * Added CAdES-BES signature verification support. =item * Added CAdES-BES signature scheme and attributes support (RFC 5126) to CMS API. =item * Added AuthEnvelopedData content type structure (RFC 5083) using AES_GCM This uses the AES-GCM parameter (RFC 5084) for the Cryptographic Message Syntax. Its purpose is to support encryption and decryption of a digital envelope that is both authenticated and encrypted using AES GCM mode. =item * L and L were made public. =back =head4 PKCS#12 API updates The default algorithms for pkcs12 creation with the PKCS12_create() function were changed to more modern PBKDF2 and AES based algorithms. The default MAC iteration count was changed to PKCS12_DEFAULT_ITER to make it equal with the password-based encryption iteration count. The default digest algorithm for the MAC computation was changed to SHA-256. The pkcs12 application now supports -legacy option that restores the previous default algorithms to support interoperability with legacy systems. Added enhanced PKCS#12 APIs which accept a library context B and (where relevant) a property query. Other APIs which handle PKCS#7 and PKCS#8 objects have also been enhanced where required. This includes: L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L, L. As part of this change the EVP_PBE_xxx APIs can also accept a library context and property query and will call an extended version of the key/IV derivation function which supports these parameters. This includes L, L and L. =head4 Windows thread synchronization changes Windows thread synchronization uses read/write primitives (SRWLock) when supported by the OS, otherwise CriticalSection continues to be used. =head4 Trace API A new generic trace API has been added which provides support for enabling instrumentation through trace output. This feature is mainly intended as an aid for developers and is disabled by default. To utilize it, OpenSSL needs to be configured with the C option. If the tracing API is enabled, the application can activate trace output by registering BIOs as trace channels for a number of tracing and debugging categories. See L. =head4 Key validation updates L and L now work for more key types. This includes RSA, DSA, ED25519, X25519, ED448 and X448. Previously (in 1.1.1) they would return -2. For key types that do not have parameters then L will always return 1. =head3 Other notable deprecations and changes =head4 The function code part of an OpenSSL error code is no longer relevant This code is now always set to zero. Related functions are deprecated. =head4 STACK and HASH macros have been cleaned up The type-safe wrappers are declared everywhere and implemented once. See L and L. =head4 The RAND_DRBG subsystem has been removed The new L is a partial replacement: the DRBG callback framework is absent. The RAND_DRBG API did not fit well into the new provider concept as implemented by EVP_RAND and EVP_RAND_CTX. =head4 Removed FIPS_mode() and FIPS_mode_set() These functions are legacy APIs that are not applicable to the new provider model. Applications should instead use L and L. =head4 Key generation is slower The Miller-Rabin test now uses 64 rounds, which is used for all prime generation, including RSA key generation. This affects the time for larger keys sizes. The default key generation method for the regular 2-prime RSA keys was changed to the FIPS186-4 B.3.6 method (Generation of Probable Primes with Conditions Based on Auxiliary Probable Primes). This method is slower than the original method. =head4 Change PBKDF2 to conform to SP800-132 instead of the older PKCS5 RFC2898 This checks that the salt length is at least 128 bits, the derived key length is at least 112 bits, and that the iteration count is at least 1000. For backwards compatibility these checks are disabled by default in the default provider, but are enabled by default in the FIPS provider. To enable or disable the checks see B in L. The parameter can be set using L. =head4 Enforce a minimum DH modulus size of 512 bits Smaller sizes now result in an error. =head4 SM2 key changes EC EVP_PKEYs with the SM2 curve have been reworked to automatically become EVP_PKEY_SM2 rather than EVP_PKEY_EC. Unlike in previous OpenSSL versions, this means that applications cannot call C to get SM2 computations. Parameter and key generation is also reworked to make it possible to generate EVP_PKEY_SM2 parameters and keys. Applications must now generate SM2 keys directly and must not create an EVP_PKEY_EC key first. It is no longer possible to import an SM2 key with domain parameters other than the SM2 elliptic curve ones. Validation of SM2 keys has been separated from the validation of regular EC keys, allowing to improve the SM2 validation process to reject loaded private keys that are not conforming to the SM2 ISO standard. In particular, a private scalar I outside the range I<< 1 <= k < n-1 >> is now correctly rejected. =head4 EVP_PKEY_set_alias_type() method has been removed This function made a B object mutable after it had been set up. In OpenSSL 3.0 it was decided that a provided key should not be able to change its type, so this function has been removed. =head4 Functions that return an internal key should be treated as read only Functions such as L behave slightly differently in OpenSSL 3.0. Previously they returned a pointer to the low-level key used internally by libcrypto. From OpenSSL 3.0 this key may now be held in a provider. Calling these functions will only return a handle on the internal key where the EVP_PKEY was constructed using this key in the first place, for example using a function or macro such as L, L, etc. Where the EVP_PKEY holds a provider managed key, then these functions now return a cached copy of the key. Changes to the internal provider key that take place after the first time the cached key is accessed will not be reflected back in the cached copy. Similarly any changes made to the cached copy by application code will not be reflected back in the internal provider key. For the above reasons the keys returned from these functions should typically be treated as read-only. To emphasise this the value returned from L, L, L and L have been made const. This may break some existing code. Applications broken by this change should be modified. The preferred solution is to refactor the code to avoid the use of these deprecated functions. Failing this the code should be modified to use a const pointer instead. The L, L, L and L functions continue to return a non-const pointer to enable them to be "freed". However they should also be treated as read-only. =head4 The public key check has moved from EVP_PKEY_derive() to EVP_PKEY_derive_set_peer() This may mean result in an error in L rather than during L. To disable this check use EVP_PKEY_derive_set_peer_ex(dh, peer, 0). =head4 The print format has cosmetic changes for some functions The output from numerous "printing" functions such as L, L, L, and other similar functions has been amended such that there may be cosmetic differences between the output observed in 1.1.1 and 3.0. This also applies to the B<-text> output from the B and B applications. =head4 Interactive mode from the B program has been removed From now on, running it without arguments is equivalent to B. =head4 The error return values from some control calls (ctrl) have changed One significant change is that controls which used to return -2 for invalid inputs, now return -1 indicating a generic error condition instead. =head4 DH and DHX key types have different settable parameters Previously (in 1.1.1) these conflicting parameters were allowed, but will now result in errors. See L for further details. This affects the behaviour of L for DH parameter generation. =head4 EVP_CIPHER_CTX_set_flags() ordering change If using a cipher from a provider the B flag can only be set B the cipher has been assigned to the cipher context. See L for more information. =head4 Validation of operation context parameters Due to move of the implementation of cryptographic operations to the providers, validation of various operation parameters can be postponed until the actual operation is executed where previously it happened immediately when an operation parameter was set. For example when setting an unsupported curve with EVP_PKEY_CTX_set_ec_paramgen_curve_nid() this function call will not fail but later keygen operations with the EVP_PKEY_CTX will fail. =head4 Removal of function code from the error codes The function code part of the error code is now always set to 0. For that reason the ERR_GET_FUNC() macro was removed. Applications must resolve the error codes only using the library number and the reason code. =head4 ChaCha20-Poly1305 cipher does not allow a truncated IV length to be used In OpenSSL 3.0 setting the IV length to any value other than 12 will result in an error. Prior to OpenSSL 3.0 the ivlen could be smaller that the required 12 byte length, using EVP_CIPHER_CTX_ctrl(ctx, EVP_CRTL_AEAD_SET_IVLEN, ivlen, NULL). This resulted in an IV that had leading zero padding. =head2 Installation and Compilation Please refer to the INSTALL.md file in the top of the distribution for instructions on how to build and install OpenSSL 3.0. Please also refer to the various platform specific NOTES files for your specific platform. =head2 Upgrading from OpenSSL 1.1.1 Upgrading to OpenSSL 3.0 from OpenSSL 1.1.1 should be relatively straight forward in most cases. The most likely area where you will encounter problems is if you have used low level APIs in your code (as discussed above). In that case you are likely to start seeing deprecation warnings when compiling your application. If this happens you have 3 options: =over 4 =item 1. Ignore the warnings. They are just warnings. The deprecated functions are still present and you may still use them. However be aware that they may be removed from a future version of OpenSSL. =item 2. Suppress the warnings. Refer to your compiler documentation on how to do this. =item 3. Remove your usage of the low level APIs. In this case you will need to rewrite your code to use the high level APIs instead =back =head3 Error code changes As OpenSSL 3.0 provides a brand new Encoder/Decoder mechanism for working with widely used file formats, application code that checks for particular error reason codes on key loading failures might need an update. Password-protected keys may deserve special attention. If only some errors are treated as an indicator that the user should be asked about the password again, it's worth testing these scenarios and processing the newly relevant codes. There may be more cases to treat specially, depending on the calling application code. =head2 Upgrading from OpenSSL 1.0.2 Upgrading to OpenSSL 3.0 from OpenSSL 1.0.2 is likely to be significantly more difficult. In addition to the issues discussed above in the section about L, the main things to be aware of are: =over 4 =item 1. The build and installation procedure has changed significantly. Check the file INSTALL.md in the top of the installation for instructions on how to build and install OpenSSL for your platform. Also read the various NOTES files in the same directory, as applicable for your platform. =item 2. Many structures have been made opaque in OpenSSL 3.0. The structure definitions have been removed from the public header files and moved to internal header files. In practice this means that you can no longer stack allocate some structures. Instead they must be heap allocated through some function call (typically those function names have a C<_new> suffix to them). Additionally you must use "setter" or "getter" functions to access the fields within those structures. For example code that previously looked like this: EVP_MD_CTX md_ctx; /* This line will now generate compiler errors */ EVP_MD_CTX_init(&md_ctx); The code needs to be amended to look like this: EVP_MD_CTX *md_ctx; md_ctx = EVP_MD_CTX_new(); ... ... EVP_MD_CTX_free(md_ctx); =item 3. Support for TLSv1.3 has been added. This has a number of implications for SSL/TLS applications. See the L for further details. =back More details about the breaking changes between OpenSSL versions 1.0.2 and 1.1.0 can be found on the L. =head3 Upgrading from the OpenSSL 2.0 FIPS Object Module The OpenSSL 2.0 FIPS Object Module was a separate download that had to be built separately and then integrated into your main OpenSSL 1.0.2 build. In OpenSSL 3.0 the FIPS support is fully integrated into the mainline version of OpenSSL and is no longer a separate download. For further information see L. The function calls FIPS_mode() and FIPS_mode_set() have been removed from OpenSSL 3.0. You should rewrite your application to not use them. See L and L for details. =head2 Completing the installation of the FIPS Module The FIPS Module will be built and installed automatically if FIPS support has been configured. The current documentation can be found in the L file. =head2 Programming Applications written to work with OpenSSL 1.1.1 will mostly just work with OpenSSL 3.0. However changes will be required if you want to take advantage of some of the new features that OpenSSL 3.0 makes available. In order to do that you need to understand some new concepts introduced in OpenSSL 3.0. Read L for further information. =head3 Library Context A library context allows different components of a complex application to each use a different library context and have different providers loaded with different configuration settings. See L for further info. If the user creates an B via L then many functions may need to be changed to pass additional parameters to handle the library context. =head4 Using a Library Context - Old functions that should be changed If a library context is needed then all EVP_* digest functions that return a B such as EVP_sha256() should be replaced with a call to L. See L. If a library context is needed then all EVP_* cipher functions that return a B such as EVP_aes_128_cbc() should be replaced vith a call to L. See L. Some functions can be passed an object that has already been set up with a library context such as L, L, L and L. If NULL is passed instead then the created object will be set up with the default library context. Use L, L, L and L if a library context is required. All functions listed below with a I have a replacement function I that takes B as an additional argument. Functions that have other mappings are listed along with the respective name. =over 4 =item * L, L, L, L, L and L =item * L =item * b2i_RSA_PVK_bio() and i2b_PVK_bio() =item * L and L =item * L, L, L, L, L, L, L, L and L =item * L =item * L, L and L =item * L =item * L, L and L =item * L and L Use L and L =item * L Use L or L. =item * L and L =item * L, L and L =item * L =item * L =item * L Use L =item * L, L and L =item * L and L =item * L =item * L and L =item * L =item * L =item * L, L, L, L and L =item * L, L, L and L =item * L and L =item * L, L, L, L, L, L, L, L, L, L, L, L, L, L, L =item * L, L, L, L and L =item * L, L and L =item * L, L and L =item * L and L =item * L =item * L =item * L =item * L =item * L =item * L and L =item * L and L =item * L =item * L =item * L and L =item * L, L, L, L and L =back =head4 New functions that use a Library context The following functions can be passed a library context if required. Passing NULL will use the default library context. =over 4 =item * L =item * L and L =item * L and L =item * L and L =item * L and L =item * L and L =item * L and L =item * L and L =item * L and L =item * L and L =item * L =item * L =item * L and L =item * L and L =item * L =item * L and L =item * L and L =item * L =item * L and L =item * L and L =item * L and L =item * L and L =item * L =item * L and L =item * L, L and L =item * L, L, L, L, L and L =item * L and L =item * L =item * L and L =item * L, L, L, L and L =back =head3 Providers Providers are described in detail here L. See also L. =head3 Fetching algorithms and property queries Implicit and Explicit Fetching is described in detail here L. =head3 Mapping EVP controls and flags to provider L parameters The existing functions for controls (such as L) and manipulating flags (such as L)internally use B to pass information to/from provider objects. See L for additional information related to parameters. For ciphers see L, L and L. For digests see L, L and L. =head3 Deprecation of Low Level Functions A significant number of APIs have been deprecated in OpenSSL 3.0. This section describes some common categories of deprecations. See L for the list of deprecated functions that refer to these categories. =head4 Providers are a replacement for engines and low-level method overrides Any accessor that uses an ENGINE is deprecated (such as EVP_PKEY_set1_engine()). Applications using engines should instead use providers. Before providers were added algorithms were overridden by changing the methods used by algorithms. All these methods such as RSA_new_method() and RSA_meth_new() are now deprecated and can be replaced by using providers instead. =head4 Deprecated i2d and d2i functions for low-level key types Any i2d and d2i functions such as d2i_DHparams() that take a low-level key type have been deprecated. Applications should instead use the L and L APIs to read and write files. See L for further details. =head4 Deprecated low-level key object getters and setters Applications that set or get low-level key objects (such as EVP_PKEY_set1_DH() or EVP_PKEY_get0()) should instead use the OSSL_ENCODER (See L) or OSSL_DECODER (See L) APIs, or alternatively use L or L. =head4 Deprecated low-level key parameter getters Functions that access low-level objects directly such as L are now deprecated. Applications should use one of L, L, l, L, L or L to access fields from an EVP_PKEY. Gettable parameters are listed in L, L, L, L, L and L. Applications may also use L to return all fields. =head4 Deprecated low-level key parameter setters Functions that access low-level objects directly such as L are now deprecated. Applications should use L to create new keys from user provided key data. Keys should be immutable once they are created, so if required the user may use L, L, and L to create a modified key. See L for more information. See L for information on generating a key using parameters. =head4 Deprecated low-level object creation Low-level objects were created using methods such as L, L and L. Applications should instead use the high-level EVP_PKEY APIs, e.g. L, L and L. See also L and L. EVP_PKEYs may be created in a variety of ways: See also L, L and L. =head4 Deprecated low-level encryption functions Low-level encryption functions such as L and L have been informally discouraged from use for a long time. Applications should instead use the high level EVP APIs L, L, and L or L, L and L. =head4 Deprecated low-level digest functions Use of low-level digest functions such as L have been informally discouraged from use for a long time. Applications should instead use the the high level EVP APIs L, L and L, or the quick one-shot L. Note that the functions L, L, L, L and L have changed to macros that use L. =head4 Deprecated low-level signing functions Use of low-level signing functions such as L have been informally discouraged for a long time. Instead applications should use L and L. See also L, L, L and L. =head4 Deprecated low-level MAC functions Low-level mac functions such as L are deprecated. Applications should instead use the new L interface, using L, L, L, L and L or the single-shot MAC function L. See L