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EVP_PKEY_CTX_new(3)                 OpenSSL                EVP_PKEY_CTX_new(3)



NAME
       EVP_PKEY_CTX_new, EVP_PKEY_CTX_new_id, EVP_PKEY_CTX_new_from_name,
       EVP_PKEY_CTX_new_from_pkey, EVP_PKEY_CTX_dup, EVP_PKEY_CTX_free,
       EVP_PKEY_CTX_is_a - public key algorithm context functions

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/evp.h>

        EVP_PKEY_CTX *EVP_PKEY_CTX_new(EVP_PKEY *pkey, ENGINE *e);
        EVP_PKEY_CTX *EVP_PKEY_CTX_new_id(int id, ENGINE *e);
        EVP_PKEY_CTX *EVP_PKEY_CTX_new_from_name(OSSL_LIB_CTX *libctx,
                                                 const char *name,
                                                 const char *propquery);
        EVP_PKEY_CTX *EVP_PKEY_CTX_new_from_pkey(OSSL_LIB_CTX *libctx,
                                                 EVP_PKEY *pkey,
                                                 const char *propquery);
        EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *ctx);
        void EVP_PKEY_CTX_free(EVP_PKEY_CTX *ctx);
        int EVP_PKEY_CTX_is_a(EVP_PKEY_CTX *ctx, const char *keytype);

DESCRIPTION
       The EVP_PKEY_CTX_new() function allocates public key algorithm context
       using the pkey key type and ENGINE e.

       The EVP_PKEY_CTX_new_id() function allocates public key algorithm
       context using the key type specified by id and ENGINE e.

       The EVP_PKEY_CTX_new_from_name() function allocates a public key
       algorithm context using the library context libctx (see
       OSSL_LIB_CTX(3)), the key type specified by name and the property query
       propquery.  None of the arguments are duplicated, so they  must remain
       unchanged for the lifetime of the returned EVP_PKEY_CTX or of any of
       its duplicates.  Read further about the possible names in "NOTES"
       below.

       The EVP_PKEY_CTX_new_from_pkey() function allocates a public key
       algorithm context using the library context libctx (see
       OSSL_LIB_CTX(3)) and the algorithm specified by pkey and the property
       query propquery. None of the arguments are duplicated, so they must
       remain unchanged for the lifetime of the returned EVP_PKEY_CTX or any
       of its duplicates.

       EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_new_from_name() are normally
       used when no EVP_PKEY structure is associated with the operations, for
       example during parameter generation or key generation for some
       algorithms.

       EVP_PKEY_CTX_dup() duplicates the context ctx. It is not supported for
       a keygen operation.

       EVP_PKEY_CTX_free() frees up the context ctx.  If ctx is NULL, nothing
       is done.

       EVP_PKEY_is_a() checks if the key type associated with ctx is keytype.

NOTES
   On EVP_PKEY_CTX
       The EVP_PKEY_CTX structure is an opaque public key algorithm context
       used by the OpenSSL high-level public key API. Contexts MUST NOT be
       shared between threads: that is it is not permissible to use the same
       context simultaneously in two threads.

   On Key Types
       We mention "key type" in this manual, which is the same as "algorithm"
       in most cases, allowing either term to be used interchangeably.  There
       are algorithms where the key type and the algorithm of the operations
       that use the keys are not the same, such as EC keys being used for
       ECDSA and ECDH operations.

       Key types are given in two different manners:

       Legacy NID or EVP_PKEY type
           This is the id used with EVP_PKEY_CTX_new_id().

           These are EVP_PKEY_RSA, EVP_PKEY_RSA_PSS, EVP_PKEY_DSA,
           EVP_PKEY_DH, EVP_PKEY_EC, EVP_PKEY_SM2, EVP_PKEY_X25519,
           EVP_PKEY_X448, and are used by legacy methods.

       Name strings
           This is the name used with EVP_PKEY_CTX_new_from_name().

           These are names like "RSA", "DSA", and what's available depends on
           what providers are currently accessible.

           The OpenSSL providers offer a set of key types available this way,
           please see OSSL_PROVIDER-FIPS(7) and OSSL_PROVIDER-default(7) and
           related documentation for more information.

RETURN VALUES
       EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_dup() return
       either the newly allocated EVP_PKEY_CTX structure or NULL if an error
       occurred.

       EVP_PKEY_CTX_free() does not return a value.

       EVP_PKEY_CTX_is_a() returns 1 for true and 0 for false.

SEE ALSO
       EVP_PKEY_new(3)

HISTORY
       The EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id(), EVP_PKEY_CTX_dup() and
       EVP_PKEY_CTX_free() functions were added in OpenSSL 1.0.0.

       The EVP_PKEY_CTX_new_from_name() and EVP_PKEY_CTX_new_from_pkey()
       functions were added in OpenSSL 3.0.

COPYRIGHT
       Copyright 2006-2021 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>.



3.0.12                            2023-05-07               EVP_PKEY_CTX_new(3)