278 lines
12 KiB
Plaintext
278 lines
12 KiB
Plaintext
=pod
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=head1 NAME
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provider-asym_cipher - The asym_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_asym_cipher_newctx(void *provctx);
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void OSSL_FUNC_asym_cipher_freectx(void *ctx);
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void *OSSL_FUNC_asym_cipher_dupctx(void *ctx);
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/* Encryption */
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int OSSL_FUNC_asym_cipher_encrypt_init(void *ctx, void *provkey,
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const OSSL_PARAM params[]);
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int OSSL_FUNC_asym_cipher_encrypt(void *ctx, unsigned char *out, size_t *outlen,
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size_t outsize, const unsigned char *in,
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size_t inlen);
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/* Decryption */
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int OSSL_FUNC_asym_cipher_decrypt_init(void *ctx, void *provkey,
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const OSSL_PARAM params[]);
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int OSSL_FUNC_asym_cipher_decrypt(void *ctx, unsigned char *out, size_t *outlen,
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size_t outsize, const unsigned char *in,
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size_t inlen);
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/* Asymmetric Cipher parameters */
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int OSSL_FUNC_asym_cipher_get_ctx_params(void *ctx, OSSL_PARAM params[]);
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const OSSL_PARAM *OSSL_FUNC_asym_cipher_gettable_ctx_params(void *provctx);
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int OSSL_FUNC_asym_cipher_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
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const OSSL_PARAM *OSSL_FUNC_asym_cipher_settable_ctx_params(void *provctx);
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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 asymmetric cipher (OSSL_OP_ASYM_CIPHER) operation enables providers to
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implement asymmetric cipher algorithms and make them available to applications
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via the API functions L<EVP_PKEY_encrypt(3)>,
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L<EVP_PKEY_decrypt(3)> and
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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_asym_cipher_newctx() has these:
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typedef void *(OSSL_FUNC_asym_cipher_newctx_fn)(void *provctx);
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static ossl_inline OSSL_FUNC_asym_cipher_newctx_fn
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OSSL_FUNC_asym_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_asym_cipher_newctx OSSL_FUNC_ASYM_CIPHER_NEWCTX
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OSSL_FUNC_asym_cipher_freectx OSSL_FUNC_ASYM_CIPHER_FREECTX
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OSSL_FUNC_asym_cipher_dupctx OSSL_FUNC_ASYM_CIPHER_DUPCTX
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OSSL_FUNC_asym_cipher_encrypt_init OSSL_FUNC_ASYM_CIPHER_ENCRYPT_INIT
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OSSL_FUNC_asym_cipher_encrypt OSSL_FUNC_ASYM_CIPHER_ENCRYPT
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OSSL_FUNC_asym_cipher_decrypt_init OSSL_FUNC_ASYM_CIPHER_DECRYPT_INIT
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OSSL_FUNC_asym_cipher_decrypt OSSL_FUNC_ASYM_CIPHER_DECRYPT
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OSSL_FUNC_asym_cipher_get_ctx_params OSSL_FUNC_ASYM_CIPHER_GET_CTX_PARAMS
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OSSL_FUNC_asym_cipher_gettable_ctx_params OSSL_FUNC_ASYM_CIPHER_GETTABLE_CTX_PARAMS
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OSSL_FUNC_asym_cipher_set_ctx_params OSSL_FUNC_ASYM_CIPHER_SET_CTX_PARAMS
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OSSL_FUNC_asym_cipher_settable_ctx_params OSSL_FUNC_ASYM_CIPHER_SETTABLE_CTX_PARAMS
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An asymmetric cipher algorithm implementation may not implement all of these
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functions.
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In order to be a consistent set of functions a provider must implement
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OSSL_FUNC_asym_cipher_newctx and OSSL_FUNC_asym_cipher_freectx.
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It must also implement both of OSSL_FUNC_asym_cipher_encrypt_init and
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OSSL_FUNC_asym_cipher_encrypt, or both of OSSL_FUNC_asym_cipher_decrypt_init and
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OSSL_FUNC_asym_cipher_decrypt.
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OSSL_FUNC_asym_cipher_get_ctx_params is optional but if it is present then so must
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OSSL_FUNC_asym_cipher_gettable_ctx_params.
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Similarly, OSSL_FUNC_asym_cipher_set_ctx_params is optional but if it is present then
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so must OSSL_FUNC_asym_cipher_settable_ctx_params.
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An asymmetric cipher algorithm must also implement some mechanism for generating,
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loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation.
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See L<provider-keymgmt(7)> for further details.
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=head2 Context Management Functions
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OSSL_FUNC_asym_cipher_newctx() should create and return a pointer to a provider side
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structure for holding context information during an asymmetric cipher operation.
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A pointer to this context will be passed back in a number of the other
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asymmetric cipher 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_asym_cipher_freectx() is passed a pointer to the provider side asymmetric
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cipher context in the I<ctx> parameter.
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This function should free any resources associated with that context.
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OSSL_FUNC_asym_cipher_dupctx() should duplicate the provider side asymmetric cipher
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context in the I<ctx> parameter and return the duplicate copy.
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=head2 Encryption Functions
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OSSL_FUNC_asym_cipher_encrypt_init() initialises a context for an asymmetric encryption
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given a provider side asymmetric cipher context in the I<ctx> parameter, and a
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pointer to a provider key object in the I<provkey> parameter.
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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_asym_cipher_set_ctx_params().
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The key object should have been previously generated, loaded or imported into
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the provider using the key management (OSSL_OP_KEYMGMT) operation (see L<provider-keymgmt(7)>).
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OSSL_FUNC_asym_cipher_encrypt() performs the actual encryption itself.
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A previously initialised asymmetric cipher context is passed in the I<ctx>
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parameter.
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The data to be encrypted is pointed to by the I<in> parameter which is I<inlen>
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bytes long.
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Unless I<out> is NULL, the encrypted data should be written to the location
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pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in
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length.
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The length of the encrypted data should be written to I<*outlen>.
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If I<out> is NULL then the maximum length of the encrypted data should be
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written to I<*outlen>.
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=head2 Decryption Functions
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OSSL_FUNC_asym_cipher_decrypt_init() initialises a context for an asymmetric decryption
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given a provider side asymmetric cipher context in the I<ctx> parameter, and a
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pointer to a provider key object in the I<provkey> parameter.
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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_asym_cipher_set_ctx_params().
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The key object should have been previously generated, loaded or imported into
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the provider using the key management (OSSL_OP_KEYMGMT) operation (see
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L<provider-keymgmt(7)>).
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OSSL_FUNC_asym_cipher_decrypt() performs the actual decryption itself.
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A previously initialised asymmetric cipher context is passed in the I<ctx>
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parameter.
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The data to be decrypted is pointed to by the I<in> parameter which is I<inlen>
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bytes long.
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Unless I<out> is NULL, the decrypted data should be written to the location
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pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in
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length.
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The length of the decrypted data should be written to I<*outlen>.
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If I<out> is NULL then the maximum length of the decrypted data should be
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written to I<*outlen>.
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=head2 Asymmetric Cipher Parameters
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See L<OSSL_PARAM(3)> for further details on the parameters structure used by
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the OSSL_FUNC_asym_cipher_get_ctx_params() and OSSL_FUNC_asym_cipher_set_ctx_params()
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functions.
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OSSL_FUNC_asym_cipher_get_ctx_params() gets asymmetric cipher parameters associated
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with the given provider side asymmetric cipher context I<ctx> and stores them in
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I<params>.
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Passing NULL for I<params> should return true.
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OSSL_FUNC_asym_cipher_set_ctx_params() sets the asymmetric cipher parameters associated
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with the given provider side asymmetric cipher context I<ctx> 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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Parameters currently recognised by built-in asymmetric cipher algorithms are as
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follows.
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Not all parameters are relevant to, or are understood by all asymmetric cipher
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algorithms:
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=over 4
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=item "pad-mode" (B<OSSL_ASYM_CIPHER_PARAM_PAD_MODE>) <UTF8 string> OR <integer>
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The type of padding to be used. The interpretation of this value will depend
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on the algorithm in use.
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=item "digest" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST>) <UTF8 string>
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Gets or sets the name of the OAEP digest algorithm used when OAEP padding is in
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use.
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=item "digest" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST>) <UTF8 string>
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Gets or sets the name of the digest algorithm used by the algorithm (where
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applicable).
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=item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST_PROPS>) <UTF8 string>
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Gets or sets the properties to use when fetching the OAEP digest algorithm.
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=item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST_PROPS>) <UTF8 string>
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Gets or sets the properties to use when fetching the cipher digest algorithm.
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=item "mgf1-digest" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST>) <UTF8 string>
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Gets or sets the name of the MGF1 digest algorithm used when OAEP or PSS padding
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is in use.
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=item "mgf1-digest-props" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS>) <UTF8 string>
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Gets or sets the properties to use when fetching the MGF1 digest algorithm.
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=item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string ptr>
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Gets the OAEP label used when OAEP padding is in use.
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=item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string>
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Sets the OAEP label used when OAEP padding is in use.
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=item "tls-client-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer>
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The TLS protocol version first requested by the client.
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=item "tls-negotiated-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer>
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The negotiated TLS protocol version.
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=item "implicit-rejection" (B<OSSL_PKEY_PARAM_IMPLICIT_REJECTION>) <unsigned integer>
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Gets of sets the use of the implicit rejection mechanism for RSA PKCS#1 v1.5
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decryption. When set (non zero value), the decryption API will return
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a deterministically random value if the PKCS#1 v1.5 padding check fails.
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This makes exploitation of the Bleichenbacher significantly harder, even
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if the code using the RSA decryption API is not implemented in side-channel
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free manner. Set by default.
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=back
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OSSL_FUNC_asym_cipher_gettable_ctx_params() and OSSL_FUNC_asym_cipher_settable_ctx_params()
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get a constant L<OSSL_PARAM(3)> array that describes the gettable and settable
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parameters, i.e. parameters that can be used with OSSL_FUNC_asym_cipherget_ctx_params()
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and OSSL_FUNC_asym_cipher_set_ctx_params() respectively.
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=head1 RETURN VALUES
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OSSL_FUNC_asym_cipher_newctx() and OSSL_FUNC_asym_cipher_dupctx() should return the newly
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created provider side asymmetric cipher context, or NULL on failure.
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All other functions should return 1 for success or 0 on error.
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=head1 SEE ALSO
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L<provider(7)>
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=head1 HISTORY
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The provider ASYM_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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