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PROVIDER-ASYM_CIPHER(7ossl)         OpenSSL        PROVIDER-ASYM_CIPHER(7ossl)



NAME

       provider-asym_cipher - The asym_cipher library <-> provider functions


SYNOPSIS

        #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_asym_cipher_newctx(void *provctx);
        void OSSL_FUNC_asym_cipher_freectx(void *ctx);
        void *OSSL_FUNC_asym_cipher_dupctx(void *ctx);

        /* Encryption */
        int OSSL_FUNC_asym_cipher_encrypt_init(void *ctx, void *provkey,
                                               const OSSL_PARAM params[]);
        int OSSL_FUNC_asym_cipher_encrypt(void *ctx, unsigned char *out, size_t *outlen,
                                          size_t outsize, const unsigned char *in,
                                          size_t inlen);

        /* Decryption */
        int OSSL_FUNC_asym_cipher_decrypt_init(void *ctx, void *provkey,
                                               const OSSL_PARAM params[]);
        int OSSL_FUNC_asym_cipher_decrypt(void *ctx, unsigned char *out, size_t *outlen,
                                          size_t outsize, const unsigned char *in,
                                          size_t inlen);

        /* Asymmetric Cipher parameters */
        int OSSL_FUNC_asym_cipher_get_ctx_params(void *ctx, OSSL_PARAM params[]);
        const OSSL_PARAM *OSSL_FUNC_asym_cipher_gettable_ctx_params(void *provctx);
        int OSSL_FUNC_asym_cipher_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
        const OSSL_PARAM *OSSL_FUNC_asym_cipher_settable_ctx_params(void *provctx);


DESCRIPTION

       This documentation is primarily aimed at provider authors. See
       provider(7) for further information.

       The asymmetric cipher (OSSL_OP_ASYM_CIPHER) operation enables providers
       to implement asymmetric cipher algorithms and make them available to
       applications via the API functions EVP_PKEY_encrypt(3),
       EVP_PKEY_decrypt(3) and other related functions).

       All "functions" mentioned here are passed as function pointers between
       libcrypto and the provider in OSSL_DISPATCH(3) arrays via
       OSSL_ALGORITHM(3) arrays that are returned by the provider's
       provider_query_operation() function (see "Provider Functions" in
       provider-base(7)).

       All these "functions" have a corresponding function type definition
       named OSSL_FUNC_{name}_fn, and a helper function to retrieve the
       function pointer from an OSSL_DISPATCH(3) element named
       OSSL_FUNC_{name}.  For example, the "function"
       OSSL_FUNC_asym_cipher_newctx() has these:

        typedef void *(OSSL_FUNC_asym_cipher_newctx_fn)(void *provctx);
        static ossl_inline OSSL_FUNC_asym_cipher_newctx_fn
            OSSL_FUNC_asym_cipher_newctx(const OSSL_DISPATCH *opf);

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

        OSSL_FUNC_asym_cipher_newctx               OSSL_FUNC_ASYM_CIPHER_NEWCTX
        OSSL_FUNC_asym_cipher_freectx              OSSL_FUNC_ASYM_CIPHER_FREECTX
        OSSL_FUNC_asym_cipher_dupctx               OSSL_FUNC_ASYM_CIPHER_DUPCTX

        OSSL_FUNC_asym_cipher_encrypt_init         OSSL_FUNC_ASYM_CIPHER_ENCRYPT_INIT
        OSSL_FUNC_asym_cipher_encrypt              OSSL_FUNC_ASYM_CIPHER_ENCRYPT

        OSSL_FUNC_asym_cipher_decrypt_init         OSSL_FUNC_ASYM_CIPHER_DECRYPT_INIT
        OSSL_FUNC_asym_cipher_decrypt              OSSL_FUNC_ASYM_CIPHER_DECRYPT

        OSSL_FUNC_asym_cipher_get_ctx_params       OSSL_FUNC_ASYM_CIPHER_GET_CTX_PARAMS
        OSSL_FUNC_asym_cipher_gettable_ctx_params  OSSL_FUNC_ASYM_CIPHER_GETTABLE_CTX_PARAMS
        OSSL_FUNC_asym_cipher_set_ctx_params       OSSL_FUNC_ASYM_CIPHER_SET_CTX_PARAMS
        OSSL_FUNC_asym_cipher_settable_ctx_params  OSSL_FUNC_ASYM_CIPHER_SETTABLE_CTX_PARAMS

       An asymmetric cipher algorithm implementation may not implement all of
       these functions.  In order to be a consistent set of functions a
       provider must implement OSSL_FUNC_asym_cipher_newctx and
       OSSL_FUNC_asym_cipher_freectx.  It must also implement both of
       OSSL_FUNC_asym_cipher_encrypt_init and OSSL_FUNC_asym_cipher_encrypt,
       or both of OSSL_FUNC_asym_cipher_decrypt_init and
       OSSL_FUNC_asym_cipher_decrypt.  OSSL_FUNC_asym_cipher_get_ctx_params is
       optional but if it is present then so must
       OSSL_FUNC_asym_cipher_gettable_ctx_params.  Similarly,
       OSSL_FUNC_asym_cipher_set_ctx_params is optional but if it is present
       then so must OSSL_FUNC_asym_cipher_settable_ctx_params.

       An asymmetric cipher algorithm must also implement some mechanism for
       generating, loading or importing keys via the key management
       (OSSL_OP_KEYMGMT) operation.  See provider-keymgmt(7) for further
       details.

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

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

       OSSL_FUNC_asym_cipher_dupctx() should duplicate the provider side
       asymmetric cipher context in the ctx parameter and return the duplicate
       copy.

   Encryption Functions
       OSSL_FUNC_asym_cipher_encrypt_init() initialises a context for an
       asymmetric encryption given a provider side asymmetric cipher context
       in the ctx parameter, and a pointer to a provider key object in the
       provkey parameter.  The params, if not NULL, should be set on the
       context in a manner similar to using
       OSSL_FUNC_asym_cipher_set_ctx_params().  The key object should have
       been previously generated, loaded or imported into the provider using
       the key management (OSSL_OP_KEYMGMT) operation (see
       provider-keymgmt(7)).  OSSL_FUNC_asym_cipher_encrypt() performs the
       actual encryption itself.  A previously initialised asymmetric cipher
       context is passed in the ctx parameter.  The data to be encrypted is
       pointed to by the in parameter which is inlen bytes long.  Unless out
       is NULL, the encrypted data should be written to the location pointed
       to by the out parameter and it should not exceed outsize bytes in
       length.  The length of the encrypted data should be written to *outlen.
       If out is NULL then the maximum length of the encrypted data should be
       written to *outlen.

   Decryption Functions
       OSSL_FUNC_asym_cipher_decrypt_init() initialises a context for an
       asymmetric decryption given a provider side asymmetric cipher context
       in the ctx parameter, and a pointer to a provider key object in the
       provkey parameter.  The params, if not NULL, should be set on the
       context in a manner similar to using
       OSSL_FUNC_asym_cipher_set_ctx_params().  The key object should have
       been previously generated, loaded or imported into the provider using
       the key management (OSSL_OP_KEYMGMT) operation (see
       provider-keymgmt(7)).

       OSSL_FUNC_asym_cipher_decrypt() performs the actual decryption itself.
       A previously initialised asymmetric cipher context is passed in the ctx
       parameter.  The data to be decrypted is pointed to by the in parameter
       which is inlen bytes long.  Unless out is NULL, the decrypted data
       should be written to the location pointed to by the out parameter and
       it should not exceed outsize bytes in length.  The length of the
       decrypted data should be written to *outlen.  If out is NULL then the
       maximum length of the decrypted data should be written to *outlen.

   Asymmetric Cipher Parameters
       See OSSL_PARAM(3) for further details on the parameters structure used
       by the OSSL_FUNC_asym_cipher_get_ctx_params() and
       OSSL_FUNC_asym_cipher_set_ctx_params() functions.

       OSSL_FUNC_asym_cipher_get_ctx_params() gets asymmetric cipher
       parameters associated with the given provider side asymmetric cipher
       context ctx and stores them in params.  Passing NULL for params should
       return true.

       OSSL_FUNC_asym_cipher_set_ctx_params() sets the asymmetric cipher
       parameters associated with the given provider side asymmetric cipher
       context ctx to params.  Any parameter settings are additional to any
       that were previously set.  Passing NULL for params should return true.

       Parameters currently recognised by built-in asymmetric cipher
       algorithms are as follows.  Not all parameters are relevant to, or are
       understood by all asymmetric cipher algorithms:

       "pad-mode" (OSSL_ASYM_CIPHER_PARAM_PAD_MODE) <UTF8 string> OR <integer>
           The type of padding to be used. The interpretation of this value
           will depend on the algorithm in use.

       "digest" (OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST) <UTF8 string>
           Gets or sets the name of the OAEP digest algorithm used when OAEP
           padding is in use.

       "digest" (OSSL_ASYM_CIPHER_PARAM_DIGEST) <UTF8 string>
           Gets or sets the name of the digest algorithm used by the algorithm
           (where applicable).

       "digest-props" (OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST_PROPS) <UTF8 string>
           Gets or sets the properties to use when fetching the OAEP digest
           algorithm.

       "digest-props" (OSSL_ASYM_CIPHER_PARAM_DIGEST_PROPS) <UTF8 string>
           Gets or sets the properties to use when fetching the cipher digest
           algorithm.

       "mgf1-digest" (OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST) <UTF8 string>
           Gets or sets the name of the MGF1 digest algorithm used when OAEP
           or PSS padding is in use.

       "mgf1-digest-props" (OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS) <UTF8
       string>
           Gets or sets the properties to use when fetching the MGF1 digest
           algorithm.

       "oaep-label" (OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL) <octet string ptr>
           Gets the OAEP label used when OAEP padding is in use.

       "oaep-label" (OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL) <octet string>
           Sets the OAEP label used when OAEP padding is in use.

       "tls-client-version" (OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION)
       <unsigned integer>
           The TLS protocol version first requested by the client.

       "tls-negotiated-version" (OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION)
       <unsigned integer>
           The negotiated TLS protocol version.

       "implicit-rejection" (OSSL_PKEY_PARAM_IMPLICIT_REJECTION) <unsigned
       integer>
           Gets of sets the use of the implicit rejection mechanism for RSA
           PKCS#1 v1.5 decryption. When set (non zero value), the decryption
           API will return a deterministically random value if the PKCS#1 v1.5
           padding check fails.  This makes exploitation of the Bleichenbacher
           significantly harder, even if the code using the RSA decryption API
           is not implemented in side-channel free manner. Set by default.

       OSSL_FUNC_asym_cipher_gettable_ctx_params() and
       OSSL_FUNC_asym_cipher_settable_ctx_params() get a constant
       OSSL_PARAM(3) array that describes the gettable and settable
       parameters, i.e. parameters that can be used with
       OSSL_FUNC_asym_cipherget_ctx_params() and
       OSSL_FUNC_asym_cipher_set_ctx_params() respectively.


RETURN VALUES

       OSSL_FUNC_asym_cipher_newctx() and OSSL_FUNC_asym_cipher_dupctx()
       should return the newly created provider side asymmetric cipher
       context, or NULL on failure.

       All other functions should return 1 for success or 0 on error.


SEE ALSO

       provider(7)


HISTORY

       The provider ASYM_CIPHER interface was introduced in OpenSSL 3.0.


COPYRIGHT

       Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.

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

3.2.0                             2023-11-23       PROVIDER-ASYM_CIPHER(7ossl)

openssl 3.2.0 - Generated Tue Nov 28 16:41:04 CST 2023
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