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Title "PROVIDER-CIPHER 7ossl"
PROVIDER-CIPHER 7ossl "2023-09-19" "3.0.11" "OpenSSL"
For nroff, turn off justification. Always turn off hyphenation; it makes
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"NAME"
provider-cipher - The cipher library <-> provider functions
"SYNOPSIS"
Header "SYNOPSIS" .Vb 2 #include <openssl/core_dispatch.h> #include <openssl/core_names.h> \& /* * None of these are actual functions, but are displayed like this for * the function signatures for functions that are offered as function * pointers in OSSL_DISPATCH arrays. */ \& /* Context management */ void *OSSL_FUNC_cipher_newctx(void *provctx); void OSSL_FUNC_cipher_freectx(void *cctx); void *OSSL_FUNC_cipher_dupctx(void *cctx); \& /* Encryption/decryption */ int OSSL_FUNC_cipher_encrypt_init(void *cctx, const unsigned char *key, size_t keylen, const unsigned char *iv, size_t ivlen, const OSSL_PARAM params[]); int OSSL_FUNC_cipher_decrypt_init(void *cctx, const unsigned char *key, size_t keylen, const unsigned char *iv, size_t ivlen, const OSSL_PARAM params[]); int OSSL_FUNC_cipher_update(void *cctx, unsigned char *out, size_t *outl, size_t outsize, const unsigned char *in, size_t inl); int OSSL_FUNC_cipher_final(void *cctx, unsigned char *out, size_t *outl, size_t outsize); int OSSL_FUNC_cipher_cipher(void *cctx, unsigned char *out, size_t *outl, size_t outsize, const unsigned char *in, size_t inl); \& /* Cipher parameter descriptors */ const OSSL_PARAM *OSSL_FUNC_cipher_gettable_params(void *provctx); \& /* Cipher operation parameter descriptors */ const OSSL_PARAM *OSSL_FUNC_cipher_gettable_ctx_params(void *cctx, void *provctx); const OSSL_PARAM *OSSL_FUNC_cipher_settable_ctx_params(void *cctx, void *provctx); \& /* Cipher parameters */ int OSSL_FUNC_cipher_get_params(OSSL_PARAM params[]); \& /* Cipher operation parameters */ int OSSL_FUNC_cipher_get_ctx_params(void *cctx, OSSL_PARAM params[]); int OSSL_FUNC_cipher_set_ctx_params(void *cctx, const OSSL_PARAM params[]); .Ve
"DESCRIPTION"
Header "DESCRIPTION" This documentation is primarily aimed at provider authors. See provider\|(7) for further information.

The \s-1CIPHER\s0 operation enables providers to implement cipher algorithms and make them available to applications via the \s-1API\s0 functions EVP_EncryptInit_ex\|(3), \fBEVP_EncryptUpdate\|(3) and EVP_EncryptFinal\|(3) (as well as the decrypt equivalents and other related functions).

All \*(L"functions\*(R" mentioned here are passed as function pointers between \fIlibcrypto and the provider in \s-1OSSL_DISPATCH\s0\|(3) arrays via \s-1OSSL_ALGORITHM\s0\|(3) arrays that are returned by the provider's \fBprovider_query_operation() function (see \*(L"Provider Functions\*(R" in provider-base\|(7)).

All these \*(L"functions\*(R" have a corresponding function type definition named OSSL_FUNC_{name}_fn, and a helper function to retrieve the function pointer from an \s-1OSSL_DISPATCH\s0\|(3) element named \fBOSSL_FUNC_{name}. For example, the \*(L"function\*(R" OSSL_FUNC_cipher_newctx() has these:

.Vb 3 typedef void *(OSSL_FUNC_cipher_newctx_fn)(void *provctx); static ossl_inline OSSL_FUNC_cipher_newctx_fn OSSL_FUNC_cipher_newctx(const OSSL_DISPATCH *opf); .Ve

\s-1OSSL_DISPATCH\s0\|(3) arrays are indexed by numbers that are provided as macros in openssl-core_dispatch.h\|(7), as follows:

.Vb 3 OSSL_FUNC_cipher_newctx OSSL_FUNC_CIPHER_NEWCTX OSSL_FUNC_cipher_freectx OSSL_FUNC_CIPHER_FREECTX OSSL_FUNC_cipher_dupctx OSSL_FUNC_CIPHER_DUPCTX \& OSSL_FUNC_cipher_encrypt_init OSSL_FUNC_CIPHER_ENCRYPT_INIT OSSL_FUNC_cipher_decrypt_init OSSL_FUNC_CIPHER_DECRYPT_INIT OSSL_FUNC_cipher_update OSSL_FUNC_CIPHER_UPDATE OSSL_FUNC_cipher_final OSSL_FUNC_CIPHER_FINAL OSSL_FUNC_cipher_cipher OSSL_FUNC_CIPHER_CIPHER \& OSSL_FUNC_cipher_get_params OSSL_FUNC_CIPHER_GET_PARAMS OSSL_FUNC_cipher_get_ctx_params OSSL_FUNC_CIPHER_GET_CTX_PARAMS OSSL_FUNC_cipher_set_ctx_params OSSL_FUNC_CIPHER_SET_CTX_PARAMS \& OSSL_FUNC_cipher_gettable_params OSSL_FUNC_CIPHER_GETTABLE_PARAMS OSSL_FUNC_cipher_gettable_ctx_params OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS OSSL_FUNC_cipher_settable_ctx_params OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS .Ve

A cipher algorithm implementation may not implement all of these functions. In order to be a consistent set of functions there must at least be a complete set of \*(L"encrypt\*(R" functions, or a complete set of \*(L"decrypt\*(R" functions, or a single \*(L"cipher\*(R" function. In all cases both the OSSL_FUNC_cipher_newctx and OSSL_FUNC_cipher_freectx functions must be present. All other functions are optional.

"Context Management Functions"
Subsection "Context Management Functions" \fBOSSL_FUNC_cipher_newctx() should create and return a pointer to a provider side structure for holding context information during a cipher operation. A pointer to this context will be passed back in a number of the other cipher operation function calls. The parameter provctx is the provider context generated during provider initialisation (see provider\|(7)).

\fBOSSL_FUNC_cipher_freectx() is passed a pointer to the provider side cipher context in the cctx parameter. This function should free any resources associated with that context.

\fBOSSL_FUNC_cipher_dupctx() should duplicate the provider side cipher context in the \fIcctx parameter and return the duplicate copy.

"Encryption/Decryption Functions"
Subsection "Encryption/Decryption Functions" \fBOSSL_FUNC_cipher_encrypt_init() initialises a cipher operation for encryption given a newly created provider side cipher context in the cctx parameter. The key to be used is given in key which is keylen bytes long. The \s-1IV\s0 to be used is given in iv which is ivlen bytes long. The params, if not \s-1NULL,\s0 should be set on the context in a manner similar to using OSSL_FUNC_cipher_set_ctx_params().

\fBOSSL_FUNC_cipher_decrypt_init() is the same as OSSL_FUNC_cipher_encrypt_init() except that it initialises the context for a decryption operation.

\fBOSSL_FUNC_cipher_update() is called to supply data to be encrypted/decrypted as part of a previously initialised cipher operation. The cctx parameter contains a pointer to a previously initialised provider side context. \fBOSSL_FUNC_cipher_update() should encrypt/decrypt inl bytes of data at the location pointed to by in. The encrypted data should be stored in out and the amount of data written to \fI*outl which should not exceed outsize bytes. \fBOSSL_FUNC_cipher_update() may be called multiple times for a single cipher operation. It is the responsibility of the cipher implementation to handle input lengths that are not multiples of the block length. In such cases a cipher implementation will typically cache partial blocks of input data until a complete block is obtained. \fIout may be the same location as in but it should not partially overlap. The same expectations apply to outsize as documented for \fBEVP_EncryptUpdate\|(3) and EVP_DecryptUpdate\|(3).

\fBOSSL_FUNC_cipher_final() completes an encryption or decryption started through previous \fBOSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init(), and OSSL_FUNC_cipher_update() calls. The cctx parameter contains a pointer to the provider side context. Any final encryption/decryption output should be written to out and the amount of data written to *outl which should not exceed outsize bytes. The same expectations apply to outsize as documented for \fBEVP_EncryptFinal\|(3) and EVP_DecryptFinal\|(3).

\fBOSSL_FUNC_cipher_cipher() performs encryption/decryption using the provider side cipher context in the cctx parameter that should have been previously initialised via a call to OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init(). This should call the raw underlying cipher function without any padding. This will be invoked in the provider as a result of the application calling \fBEVP_Cipher\|(3). The application is responsible for ensuring that the input is a multiple of the block length. The data to be encrypted/decrypted will be in in, and it will be inl bytes in length. The output from the encryption/decryption should be stored in out and the amount of data stored should be put in *outl which should be no more than \fIoutsize bytes.

"Cipher Parameters"
Subsection "Cipher Parameters" See \s-1OSSL_PARAM\s0\|(3) for further details on the parameters structure used by these functions.

\fBOSSL_FUNC_cipher_get_params() gets details of the algorithm implementation and stores them in params.

\fBOSSL_FUNC_cipher_set_ctx_params() sets cipher operation parameters for the provider side cipher context cctx to params. Any parameter settings are additional to any that were previously set. Passing \s-1NULL\s0 for params should return true.

\fBOSSL_FUNC_cipher_get_ctx_params() gets cipher operation details details from the given provider side cipher context cctx and stores them in params. Passing \s-1NULL\s0 for params should return true.

\fBOSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params(), and OSSL_FUNC_cipher_settable_ctx_params() all return constant \s-1OSSL_PARAM\s0\|(3) arrays as descriptors of the parameters that OSSL_FUNC_cipher_get_params(), \fBOSSL_FUNC_cipher_get_ctx_params(), and OSSL_FUNC_cipher_set_ctx_params() can handle, respectively. OSSL_FUNC_cipher_gettable_ctx_params() and \fBOSSL_FUNC_cipher_settable_ctx_params() will return the parameters associated with the provider side context cctx in its current state if it is not \s-1NULL.\s0 Otherwise, they return the parameters associated with the provider side algorithm provctx.

Parameters currently recognised by built-in ciphers are listed in \*(L"\s-1PARAMETERS\*(R"\s0 in EVP_EncryptInit\|(3). Not all parameters are relevant to, or are understood by all ciphers.

"RETURN VALUES"
Header "RETURN VALUES" \fBOSSL_FUNC_cipher_newctx() and OSSL_FUNC_cipher_dupctx() should return the newly created provider side cipher context, or \s-1NULL\s0 on failure.

\fBOSSL_FUNC_cipher_encrypt_init(), OSSL_FUNC_cipher_decrypt_init(), OSSL_FUNC_cipher_update(), \fBOSSL_FUNC_cipher_final(), OSSL_FUNC_cipher_cipher(), OSSL_FUNC_cipher_get_params(), \fBOSSL_FUNC_cipher_get_ctx_params() and OSSL_FUNC_cipher_set_ctx_params() should return 1 for success or 0 on error.

\fBOSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params() and \fBOSSL_FUNC_cipher_settable_ctx_params() should return a constant \s-1OSSL_PARAM\s0\|(3) array, or \s-1NULL\s0 if none is offered.

"SEE ALSO"
Header "SEE ALSO" \fBprovider\|(7), \s-1OSSL_PROVIDER-FIPS\s0\|(7), OSSL_PROVIDER-default\|(7), \fBOSSL_PROVIDER-legacy\|(7), \s-1EVP_CIPHER-AES\s0\|(7), \s-1EVP_CIPHER-ARIA\s0\|(7), \s-1EVP_CIPHER-BLOWFISH\s0\|(7), \s-1EVP_CIPHER-CAMELLIA\s0\|(7), \s-1EVP_CIPHER-CAST\s0\|(7), \s-1EVP_CIPHER-CHACHA\s0\|(7), \s-1EVP_CIPHER-DES\s0\|(7), \s-1EVP_CIPHER-IDEA\s0\|(7), \s-1EVP_CIPHER-RC2\s0\|(7), \s-1EVP_CIPHER-RC4\s0\|(7), \s-1EVP_CIPHER-RC5\s0\|(7), \s-1EVP_CIPHER-SEED\s0\|(7), \s-1EVP_CIPHER-SM4\s0\|(7), \s-1EVP_CIPHER-NULL\s0\|(7), \fBlife_cycle-cipher\|(7), EVP_EncryptInit\|(3)
"HISTORY"
Header "HISTORY" The provider \s-1CIPHER\s0 interface was introduced in OpenSSL 3.0.
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.