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
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);
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 NID
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.
to an ASN1_OBJECT structure, its long name and its short name
respectively, or NULL
is an error occurred.
corresponding NID for the object o
, the long name <ln> or the
short name <sn> respectively or NID_undef if an error occurred.
returns NID corresponding to text string <s>.
can be a long name, a short name or the numerical respresentation of
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.
converts the ASN1_OBJECT a
into a textual
representation. The representation is written as a null terminated string to
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.
. If the two are identical 0 is
returns a copy of o
adds a new object to the internal table. oid
numerical form of the object, sn
the short name and ln
name. A new NID is returned for the created object.
cleans up OpenSSLs internal object table: this should be
called before an application exits if any new objects were added using
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
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
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
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
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:
new_nid = OBJ_create("188.8.131.52", "NewOID", "New Object Identifier");
obj = OBJ_nid2obj(new_nid);
Create a new object directly:
obj = OBJ_txt2obj("184.108.40.206", 1);
is awkward and messy to use: it doesn't follow the
convention of other OpenSSL functions where the buffer can be set to
to determine the amount of data that should be written. Instead
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.
returns an ASN1_OBJECT
structure or NULL
an error occurred. It returns a pointer to an internal table and does not
allocate memory; ASN1_OBJECT_free()
will have no effect.
returns a valid string or
return a NID or NID_undef