Section: OpenSSL (3)
Updated: 2021-03-26
Page Index


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  


 #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);



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.  


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().  


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.  


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


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>.