NAME

       X509_PUBKEY_new, X509_PUBKEY_free, X509_PUBKEY_set, X509_PUBKEY_get0, X509_PUBKEY_get,
       d2i_PUBKEY, i2d_PUBKEY, d2i_PUBKEY_bio, d2i_PUBKEY_fp, i2d_PUBKEY_fp, i2d_PUBKEY_bio,
       X509_PUBKEY_set0_param, X509_PUBKEY_get0_param - SubjectPublicKeyInfo public key functions

SYNOPSIS

        #include <openssl/x509.h>

        X509_PUBKEY *X509_PUBKEY_new(void);
        void X509_PUBKEY_free(X509_PUBKEY *a);

        int X509_PUBKEY_set(X509_PUBKEY **x, EVP_PKEY *pkey);
        EVP_PKEY *X509_PUBKEY_get0(X509_PUBKEY *key);
        EVP_PKEY *X509_PUBKEY_get(X509_PUBKEY *key);

        EVP_PKEY *d2i_PUBKEY(EVP_PKEY **a, const unsigned char **pp, long length);
        int i2d_PUBKEY(EVP_PKEY *a, unsigned char **pp);

        EVP_PKEY *d2i_PUBKEY_bio(BIO *bp, EVP_PKEY **a);
        EVP_PKEY *d2i_PUBKEY_fp(FILE *fp, EVP_PKEY **a);

        int i2d_PUBKEY_fp(FILE *fp, EVP_PKEY *pkey);
        int i2d_PUBKEY_bio(BIO *bp, EVP_PKEY *pkey);

        int X509_PUBKEY_set0_param(X509_PUBKEY *pub, ASN1_OBJECT *aobj,
                                   int ptype, void *pval,
                                   unsigned char *penc, int penclen);
        int X509_PUBKEY_get0_param(ASN1_OBJECT **ppkalg,
                                   const unsigned char **pk, int *ppklen,
                                   X509_ALGOR **pa, X509_PUBKEY *pub);

DESCRIPTION

       The X509_PUBKEY structure represents the ASN.1 SubjectPublicKeyInfo structure defined in
       RFC5280 and used in certificates and certificate requests.

       X509_PUBKEY_new() allocates and initializes an X509_PUBKEY structure.

       X509_PUBKEY_free() frees up X509_PUBKEY structure a. If a is NULL nothing is done.

       X509_PUBKEY_set() sets the public key in *x to the public key contained in the EVP_PKEY
       structure pkey. If *x is not NULL any existing public key structure will be freed.

       X509_PUBKEY_get0() returns the public key contained in key. The returned value is an
       internal pointer which MUST NOT be freed after use.

       X509_PUBKEY_get() is similar to X509_PUBKEY_get0() except the reference count on the
       returned key is incremented so it MUST be freed using EVP_PKEY_free() after use.

       d2i_PUBKEY() and i2d_PUBKEY() decode and encode an EVP_PKEY structure using
       SubjectPublicKeyInfo format. They otherwise follow the conventions of other ASN.1
       functions such as d2i_X509().

       d2i_PUBKEY_bio(), d2i_PUBKEY_fp(), i2d_PUBKEY_bio() and i2d_PUBKEY_fp() are similar to
       d2i_PUBKEY() and i2d_PUBKEY() except they decode or encode using a BIO or FILE pointer.

       X509_PUBKEY_set0_param() sets the public key parameters of pub. The OID associated with
       the algorithm is set to aobj. The type of the algorithm parameters is set to type using
       the structure pval.  The encoding of the public key itself is set to the penclen bytes
       contained in buffer penc. On success ownership of all the supplied parameters is passed to
       pub so they must not be freed after the call.

       X509_PUBKEY_get0_param() retrieves the public key parameters from pub, *ppkalg is set to
       the associated OID and the encoding consists of *ppklen bytes at *pk, *pa is set to the
       associated AlgorithmIdentifier for the public key. If the value of any of these parameters
       is not required it can be set to NULL. All of the retrieved pointers are internal and must
       not be freed after the call.

NOTES

       The X509_PUBKEY functions can be used to encode and decode public keys in a standard
       format.

       In many cases applications will not call the X509_PUBKEY functions directly: they will
       instead call wrapper functions such as X509_get0_pubkey().

RETURN VALUES

       If the allocation fails, X509_PUBKEY_new() returns NULL and sets an error code that can be
       obtained by ERR_get_error(3).

       Otherwise it returns a pointer to the newly allocated structure.

       X509_PUBKEY_free() does not return a value.

       X509_PUBKEY_get0() and X509_PUBKEY_get() return a pointer to an EVP_PKEY structure or NULL
       if an error occurs.

       X509_PUBKEY_set(), X509_PUBKEY_set0_param() and X509_PUBKEY_get0_param() return 1 for
       success and 0 if an error occurred.

SEE ALSO

       d2i_X509(3), ERR_get_error(3), X509_get_pubkey(3),

COPYRIGHT

       Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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>.