OBJ_nid2obj(3)               OpenSSL               OBJ_nid2obj(3)


     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


      #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 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);
      void OBJ_cleanup(void);


     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

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

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OBJ_nid2obj(3)               OpenSSL               OBJ_nid2obj(3)

     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.

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

     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.

     OBJ_cleanup() cleans up OpenSSLs internal object table: this
     should be called before an application exits if any new
     objects were added using OBJ_create().


     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

      #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

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OBJ_nid2obj(3)               OpenSSL               OBJ_nid2obj(3)

     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.


     Create an object for commonName:

      ASN1_OBJECT *o;
      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;
      ASN1_OBJECT *obj;

      new_nid = OBJ_create("", "NewOID", "New Object Identifier");

      obj = OBJ_nid2obj(new_nid);

     Create a new object directly:

      obj = OBJ_txt2obj("", 1);


     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.


     OBJ_nid2obj() returns an ASN1_OBJECT structure or NULL is an

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OBJ_nid2obj(3)               OpenSSL               OBJ_nid2obj(3)

     error occurred.  It returns a pointer to an internal table
     and does not allocate memory; ASN1_OBJECT_free() will have
     no effect.

     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.





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See also OBJ_cleanup(3)
See also OBJ_cmp(3)
See also OBJ_create(3)
See also OBJ_dup(3)
See also OBJ_ln2nid(3)
See also OBJ_nid2ln(3)
See also OBJ_nid2obj(3)
See also OBJ_obj2nid(3)
See also OBJ_obj2txt(3)
See also OBJ_sn2nid(3)
See also OBJ_txt2nid(3)
See also OBJ_txt2obj(3)

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