=pod

=head1 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.

=head1 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);

=head1 DESCRIPTION

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

X509_PUBKEY_new() allocates and initializes an B<X509_PUBKEY> structure.

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

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

X509_PUBKEY_get0() returns the public key contained in B<key>. The returned
value is an internal pointer which B<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 B<MUST> be freed using
EVP_PKEY_free() after use.

d2i_PUBKEY() and i2d_PUBKEY() decode and encode an B<EVP_PKEY> structure
using B<SubjectPublicKeyInfo> format. They otherise 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
B<BIO> or B<FILE> pointer.

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

X509_PUBKEY_get0_param() retrieves the public key parameters from B<pub>,
B<*ppkalg> is set to the associated OID and the encoding consists of
B<*ppklen> bytes at B<*pk>, B<*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 B<NULL>. All of the
retrieved pointers are internal and must not be freed after the
call.

=head1 NOTES

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

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

=head1 RETURN VALUES

If the allocation fails, X509_PUBKEY_new() returns B<NULL> and sets an error
code that can be obtained by L<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 B<EVP_PKEY>
structure or B<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.

=head1 SEE ALSO

L<d2i_X509(3)>,
L<ERR_get_error(3)>,
L<X509_get_pubkey(3)>,

=cut
