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6ebdbba76a
The EVP interface explicitly allows in-place encryption/decryption, but this fact is just 'partially' documented in `EVP_EncryptUpdate(3)` (pun intended): the manual page mentions only operation failure in case of 'partial' overlaps. This is not even correct, because the check for partially overlapping buffers is only implemented in legacy code paths. Currently, in-place encryption/decryption is only documented for RSA (`RSA_public_encrypt(3)`) and DES (`DES_ecb_encrypt(3)`), as well as in the provider interface (`provider-cipher(7)`). This commit amends `EVP_EncryptUpdate(3)` and `provider-cipher(7)` to make the front-end and back-end documentation consistent. Reviewed-by: Tomas Mraz <tomas@openssl.org> Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com> (Merged from https://github.com/openssl/openssl/pull/22875)
252 lines
11 KiB
Plaintext
252 lines
11 KiB
Plaintext
=pod
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=head1 NAME
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provider-cipher - The cipher library E<lt>-E<gt> provider functions
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=head1 SYNOPSIS
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=for openssl multiple includes
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#include <openssl/core_dispatch.h>
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#include <openssl/core_names.h>
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/*
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* None of these are actual functions, but are displayed like this for
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* the function signatures for functions that are offered as function
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* pointers in OSSL_DISPATCH arrays.
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*/
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/* Context management */
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void *OSSL_FUNC_cipher_newctx(void *provctx);
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void OSSL_FUNC_cipher_freectx(void *cctx);
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void *OSSL_FUNC_cipher_dupctx(void *cctx);
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/* Encryption/decryption */
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int OSSL_FUNC_cipher_encrypt_init(void *cctx, const unsigned char *key,
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size_t keylen, const unsigned char *iv,
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size_t ivlen, const OSSL_PARAM params[]);
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int OSSL_FUNC_cipher_decrypt_init(void *cctx, const unsigned char *key,
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size_t keylen, const unsigned char *iv,
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size_t ivlen, const OSSL_PARAM params[]);
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int OSSL_FUNC_cipher_update(void *cctx, unsigned char *out, size_t *outl,
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size_t outsize, const unsigned char *in, size_t inl);
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int OSSL_FUNC_cipher_final(void *cctx, unsigned char *out, size_t *outl,
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size_t outsize);
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int OSSL_FUNC_cipher_cipher(void *cctx, unsigned char *out, size_t *outl,
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size_t outsize, const unsigned char *in, size_t inl);
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/* Cipher parameter descriptors */
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const OSSL_PARAM *OSSL_FUNC_cipher_gettable_params(void *provctx);
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/* Cipher operation parameter descriptors */
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const OSSL_PARAM *OSSL_FUNC_cipher_gettable_ctx_params(void *cctx,
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void *provctx);
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const OSSL_PARAM *OSSL_FUNC_cipher_settable_ctx_params(void *cctx,
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void *provctx);
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/* Cipher parameters */
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int OSSL_FUNC_cipher_get_params(OSSL_PARAM params[]);
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/* Cipher operation parameters */
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int OSSL_FUNC_cipher_get_ctx_params(void *cctx, OSSL_PARAM params[]);
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int OSSL_FUNC_cipher_set_ctx_params(void *cctx, const OSSL_PARAM params[]);
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=head1 DESCRIPTION
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This documentation is primarily aimed at provider authors. See L<provider(7)>
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for further information.
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The CIPHER operation enables providers to implement cipher algorithms and make
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them available to applications via the API functions L<EVP_EncryptInit_ex(3)>,
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L<EVP_EncryptUpdate(3)> and L<EVP_EncryptFinal(3)> (as well as the decrypt
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equivalents and other related functions).
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All "functions" mentioned here are passed as function pointers between
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F<libcrypto> and the provider in L<OSSL_DISPATCH(3)> arrays via
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L<OSSL_ALGORITHM(3)> arrays that are returned by the provider's
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provider_query_operation() function
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(see L<provider-base(7)/Provider Functions>).
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All these "functions" have a corresponding function type definition
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named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
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function pointer from an L<OSSL_DISPATCH(3)> element named
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B<OSSL_FUNC_{name}>.
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For example, the "function" OSSL_FUNC_cipher_newctx() has these:
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typedef void *(OSSL_FUNC_cipher_newctx_fn)(void *provctx);
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static ossl_inline OSSL_FUNC_cipher_newctx_fn
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OSSL_FUNC_cipher_newctx(const OSSL_DISPATCH *opf);
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L<OSSL_DISPATCH(3)> arrays are indexed by numbers that are provided as
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macros in L<openssl-core_dispatch.h(7)>, as follows:
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OSSL_FUNC_cipher_newctx OSSL_FUNC_CIPHER_NEWCTX
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OSSL_FUNC_cipher_freectx OSSL_FUNC_CIPHER_FREECTX
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OSSL_FUNC_cipher_dupctx OSSL_FUNC_CIPHER_DUPCTX
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OSSL_FUNC_cipher_encrypt_init OSSL_FUNC_CIPHER_ENCRYPT_INIT
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OSSL_FUNC_cipher_decrypt_init OSSL_FUNC_CIPHER_DECRYPT_INIT
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OSSL_FUNC_cipher_update OSSL_FUNC_CIPHER_UPDATE
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OSSL_FUNC_cipher_final OSSL_FUNC_CIPHER_FINAL
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OSSL_FUNC_cipher_cipher OSSL_FUNC_CIPHER_CIPHER
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OSSL_FUNC_cipher_get_params OSSL_FUNC_CIPHER_GET_PARAMS
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OSSL_FUNC_cipher_get_ctx_params OSSL_FUNC_CIPHER_GET_CTX_PARAMS
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OSSL_FUNC_cipher_set_ctx_params OSSL_FUNC_CIPHER_SET_CTX_PARAMS
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OSSL_FUNC_cipher_gettable_params OSSL_FUNC_CIPHER_GETTABLE_PARAMS
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OSSL_FUNC_cipher_gettable_ctx_params OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS
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OSSL_FUNC_cipher_settable_ctx_params OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS
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A cipher algorithm implementation may not implement all of these functions.
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In order to be a consistent set of functions there must at least be a complete
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set of "encrypt" functions, or a complete set of "decrypt" functions, or a
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single "cipher" function.
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In all cases both the OSSL_FUNC_cipher_newctx and OSSL_FUNC_cipher_freectx functions must be
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present.
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All other functions are optional.
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=head2 Context Management Functions
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OSSL_FUNC_cipher_newctx() should create and return a pointer to a provider side
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structure for holding context information during a cipher operation.
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A pointer to this context will be passed back in a number of the other cipher
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operation function calls.
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The parameter I<provctx> is the provider context generated during provider
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initialisation (see L<provider(7)>).
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OSSL_FUNC_cipher_freectx() is passed a pointer to the provider side cipher context in
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the I<cctx> parameter.
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This function should free any resources associated with that context.
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OSSL_FUNC_cipher_dupctx() should duplicate the provider side cipher context in the
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I<cctx> parameter and return the duplicate copy.
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=head2 Encryption/Decryption Functions
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OSSL_FUNC_cipher_encrypt_init() initialises a cipher operation for encryption given a
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newly created provider side cipher context in the I<cctx> parameter.
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The key to be used is given in I<key> which is I<keylen> bytes long.
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The IV to be used is given in I<iv> which is I<ivlen> bytes long.
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The I<params>, if not NULL, should be set on the context in a manner similar to
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using OSSL_FUNC_cipher_set_ctx_params().
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OSSL_FUNC_cipher_decrypt_init() is the same as OSSL_FUNC_cipher_encrypt_init() except that it
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initialises the context for a decryption operation.
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OSSL_FUNC_cipher_update() is called to supply data to be encrypted/decrypted as part of
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a previously initialised cipher operation.
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The I<cctx> parameter contains a pointer to a previously initialised provider
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side context.
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OSSL_FUNC_cipher_update() should encrypt/decrypt I<inl> bytes of data at the location
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pointed to by I<in>.
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The encrypted data should be stored in I<out> and the amount of data written to
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I<*outl> which should not exceed I<outsize> bytes.
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OSSL_FUNC_cipher_update() may be called multiple times for a single cipher operation.
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It is the responsibility of the cipher implementation to handle input lengths
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that are not multiples of the block length.
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In such cases a cipher implementation will typically cache partial blocks of
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input data until a complete block is obtained.
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The pointers I<out> and I<in> may point to the same location, in which
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case the encryption must be done in-place. If I<out> and I<in> point to different
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locations, the requirements of L<EVP_EncryptUpdate(3)> and L<EVP_DecryptUpdate(3)>
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guarantee that the two buffers are disjoint.
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Similarly, the requirements of L<EVP_EncryptUpdate(3)> and L<EVP_DecryptUpdate(3)>
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ensure that the buffer pointed to by I<out> contains sufficient room for the
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operation being performed.
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OSSL_FUNC_cipher_final() completes an encryption or decryption started through previous
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OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init(), and OSSL_FUNC_cipher_update()
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calls.
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The I<cctx> parameter contains a pointer to the provider side context.
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Any final encryption/decryption output should be written to I<out> and the
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amount of data written to I<*outl> which should not exceed I<outsize> bytes.
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The same expectations apply to I<outsize> as documented for
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L<EVP_EncryptFinal(3)> and L<EVP_DecryptFinal(3)>.
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OSSL_FUNC_cipher_cipher() performs encryption/decryption using the provider side cipher
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context in the I<cctx> parameter that should have been previously initialised via
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a call to OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init().
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This should call the raw underlying cipher function without any padding.
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This will be invoked in the provider as a result of the application calling
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L<EVP_Cipher(3)>.
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The application is responsible for ensuring that the input is a multiple of the
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block length.
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The data to be encrypted/decrypted will be in I<in>, and it will be I<inl> bytes
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in length.
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The output from the encryption/decryption should be stored in I<out> and the
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amount of data stored should be put in I<*outl> which should be no more than
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I<outsize> bytes.
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=head2 Cipher Parameters
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See L<OSSL_PARAM(3)> for further details on the parameters structure used by
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these functions.
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OSSL_FUNC_cipher_get_params() gets details of the algorithm implementation
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and stores them in I<params>.
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OSSL_FUNC_cipher_set_ctx_params() sets cipher operation parameters for the
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provider side cipher context I<cctx> to I<params>.
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Any parameter settings are additional to any that were previously set.
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Passing NULL for I<params> should return true.
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OSSL_FUNC_cipher_get_ctx_params() gets cipher operation details details from
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the given provider side cipher context I<cctx> and stores them in I<params>.
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Passing NULL for I<params> should return true.
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OSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params(),
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and OSSL_FUNC_cipher_settable_ctx_params() all return constant L<OSSL_PARAM(3)>
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arrays as descriptors of the parameters that OSSL_FUNC_cipher_get_params(),
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OSSL_FUNC_cipher_get_ctx_params(), and OSSL_FUNC_cipher_set_ctx_params()
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can handle, respectively. OSSL_FUNC_cipher_gettable_ctx_params() and
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OSSL_FUNC_cipher_settable_ctx_params() will return the parameters associated
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with the provider side context I<cctx> in its current state if it is
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not NULL. Otherwise, they return the parameters associated with the
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provider side algorithm I<provctx>.
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Parameters currently recognised by built-in ciphers are listed in
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L<EVP_EncryptInit(3)/PARAMETERS>.
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Not all parameters are relevant to, or are understood by all ciphers.
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=head1 RETURN VALUES
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OSSL_FUNC_cipher_newctx() and OSSL_FUNC_cipher_dupctx() should return the newly created
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provider side cipher context, or NULL on failure.
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OSSL_FUNC_cipher_encrypt_init(), OSSL_FUNC_cipher_decrypt_init(), OSSL_FUNC_cipher_update(),
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OSSL_FUNC_cipher_final(), OSSL_FUNC_cipher_cipher(), OSSL_FUNC_cipher_get_params(),
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OSSL_FUNC_cipher_get_ctx_params() and OSSL_FUNC_cipher_set_ctx_params() should return 1 for
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success or 0 on error.
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OSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params() and
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OSSL_FUNC_cipher_settable_ctx_params() should return a constant L<OSSL_PARAM(3)>
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array, or NULL if none is offered.
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=head1 SEE ALSO
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L<provider(7)>, L<OSSL_PROVIDER-FIPS(7)>, L<OSSL_PROVIDER-default(7)>,
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L<OSSL_PROVIDER-legacy(7)>,
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L<EVP_CIPHER-AES(7)>, L<EVP_CIPHER-ARIA(7)>, L<EVP_CIPHER-BLOWFISH(7)>,
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L<EVP_CIPHER-CAMELLIA(7)>, L<EVP_CIPHER-CAST(7)>, L<EVP_CIPHER-CHACHA(7)>,
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L<EVP_CIPHER-DES(7)>, L<EVP_CIPHER-IDEA(7)>, L<EVP_CIPHER-RC2(7)>,
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L<EVP_CIPHER-RC4(7)>, L<EVP_CIPHER-RC5(7)>, L<EVP_CIPHER-SEED(7)>,
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L<EVP_CIPHER-SM4(7)>, L<EVP_CIPHER-NULL(7)>,
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L<life_cycle-cipher(7)>, L<EVP_EncryptInit(3)>
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=head1 HISTORY
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The provider CIPHER interface was introduced in OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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