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OBJ_NID2OBJ(3)			    OpenSSL			OBJ_NID2OBJ(3)

NAME
       i2t_ASN1_OBJECT,	OBJ_length, OBJ_get0_data, OBJ_nid2obj,	OBJ_nid2ln,
       OBJ_nid2sn, OBJ_obj2nid,	OBJ_txt2nid, OBJ_ln2nid, OBJ_sn2nid, OBJ_cmp,
       OBJ_dup,	OBJ_txt2obj, OBJ_obj2txt, OBJ_create, OBJ_cleanup - ASN1
       object utility functions

SYNOPSIS
	#include <openssl/objects.h>

	ASN1_OBJECT *OBJ_nid2obj(int n);
	const char *OBJ_nid2ln(int n);
	const char *OBJ_nid2sn(int n);

	int OBJ_obj2nid(const ASN1_OBJECT *o);
	int OBJ_ln2nid(const char *ln);
	int OBJ_sn2nid(const char *sn);

	int OBJ_txt2nid(const char *s);

	ASN1_OBJECT *OBJ_txt2obj(const char *s,	int no_name);
	int OBJ_obj2txt(char *buf, int buf_len,	const ASN1_OBJECT *a, int no_name);

	int i2t_ASN1_OBJECT(char *buf, int buf_len, const ASN1_OBJECT *a);

	int OBJ_cmp(const ASN1_OBJECT *a, const	ASN1_OBJECT *b);
	ASN1_OBJECT *OBJ_dup(const ASN1_OBJECT *o);

	int OBJ_create(const char *oid,	const char *sn,	const char *ln);

	size_t OBJ_length(const	ASN1_OBJECT *obj);
	const unsigned char *OBJ_get0_data(const ASN1_OBJECT *obj);

       Deprecated:

	#if OPENSSL_API_COMPAT < 0x10100000L
	void OBJ_cleanup(void)
	#endif

DESCRIPTION
       The ASN1	object utility functions process ASN1_OBJECT structures	which
       are a representation of the ASN1	OBJECT IDENTIFIER (OID)	type.  For
       convenience, OIDs are usually represented in source code	as numeric
       identifiers, or NIDs.  OpenSSL has an internal table of OIDs that are
       generated when the library is built, and	their corresponding NIDs are
       available as defined constants.	For the	functions below, application
       code should treat all returned values --	OIDs, NIDs, or names --	as
       constants.

       OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the	NID n to an
       ASN1_OBJECT structure, its long name and	its short name respectively,
       or NULL if an error occurred.

       OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() return	the corresponding NID
       for the object o, the long name <ln> or the short name <sn>
       respectively or NID_undef if an error occurred.

       OBJ_txt2nid() returns NID corresponding to text string <s>. s can be a
       long name, a short name or the numerical	representation of an object.

       OBJ_txt2obj() converts the text string s	into an	ASN1_OBJECT structure.
       If no_name is 0 then long names and short names will be interpreted as
       well as numerical forms.	If no_name is 1	only the numerical form	is
       acceptable.

       OBJ_obj2txt() converts the ASN1_OBJECT a	into a textual representation.
       The representation is written as	a null terminated string to buf	at
       most buf_len bytes are written, truncating the result if	necessary.
       The total amount	of space required is returned. If no_name is 0 then if
       the object has a	long or	short name then	that will be used, otherwise
       the numerical form will be used.	If no_name is 1	then the numerical
       form will always	be used.

       i2t_ASN1_OBJECT() is the	same as	OBJ_obj2txt() with the no_name set to
       zero.

       OBJ_cmp() compares a to b. If the two are identical 0 is	returned.

       OBJ_dup() returns a copy	of o.

       OBJ_create() adds a new object to the internal table. oid is the
       numerical form of the object, sn	the short name and ln the long name. A
       new NID is returned for the created object in case of success and
       NID_undef in case of failure.

       OBJ_length() returns the	size of	the content octets of obj.

       OBJ_get0_data() returns a pointer to the	content	octets of obj.	The
       returned	pointer	is an internal pointer which must not be freed.

       OBJ_cleanup() releases any resources allocated by creating new objects.

NOTES
       Objects in OpenSSL can have a short name, a long	name and a numerical
       identifier (NID)	associated with	them. A	standard set of	objects	is
       represented in an internal table. The appropriate values	are defined in
       the header file objects.h.

       For example the OID for commonName has the following definitions:

	#define	SN_commonName			"CN"
	#define	LN_commonName			"commonName"
	#define	NID_commonName			13

       New objects can be added	by calling OBJ_create().

       Table objects have certain advantages over other	objects: for example
       their NIDs can be used in a C language switch statement.	They are also
       static constant structures which	are shared: that is there is only a
       single constant structure for each table	object.

       Objects which are not in	the table have the NID value NID_undef.

       Objects do not need to be in the	internal tables	to be processed, the
       functions OBJ_txt2obj() and OBJ_obj2txt() can process the numerical
       form of an OID.

       Some objects are	used to	represent algorithms which do not have a
       corresponding ASN.1 OBJECT IDENTIFIER encoding (for example no OID
       currently exists	for a particular algorithm). As	a result they cannot
       be encoded or decoded as	part of	ASN.1 structures. Applications can
       determine if there is a corresponding OBJECT IDENTIFIER by checking
       OBJ_length() is not zero.

       These functions cannot return const because an ASN1_OBJECT can
       represent both an internal, constant, OID and a dynamically-created
       one.  The latter	cannot be constant because it needs to be freed	after
       use.

RETURN VALUES
       OBJ_nid2obj() returns an	ASN1_OBJECT structure or NULL is an error
       occurred.

       OBJ_nid2ln() and	OBJ_nid2sn() returns a valid string or NULL on error.

       OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return a
       NID or NID_undef	on error.

EXAMPLES
       Create an object	for commonName:

	ASN1_OBJECT *o = OBJ_nid2obj(NID_commonName);

       Check if	an object is commonName

	if (OBJ_obj2nid(obj) ==	NID_commonName)
	    /* Do something */

       Create a	new NID	and initialize an object from it:

	int new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier");
	ASN1_OBJECT *obj = OBJ_nid2obj(new_nid);

       Create a	new object directly:

	obj = OBJ_txt2obj("1.2.3.4", 1);

BUGS
       OBJ_obj2txt() is	awkward	and messy to use: it doesn't follow the
       convention of other OpenSSL functions where the buffer can be set to
       NULL to determine the amount of data that should	be written.  Instead
       buf must	point to a valid buffer	and buf_len should be set to a
       positive	value. A buffer	length of 80 should be more than enough	to
       handle any OID encountered in practice.

SEE ALSO
       ERR_get_error(3)

HISTORY
       OBJ_cleanup() was deprecated in OpenSSL 1.1.0 by	OPENSSL_init_crypto(3)
       and should not be used.

COPYRIGHT
       Copyright 2002-2019 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>.

1.1.1d				  2019-09-10			OBJ_NID2OBJ(3)

NAME | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUES | EXAMPLES | BUGS | SEE ALSO | HISTORY | COPYRIGHT

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