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, OBJ_add_sigid - 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 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);
int OBJ_add_sigid(int signid, int dig_id, int pkey_id);
The following function has been deprecated since OpenSSL 1.1.0, and can be
hidden entirely by defining
OPENSSL_API_COMPAT with a suitable version
value, see
openssl_user_macros(7):
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 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. Unless
buf is NULL, the representation is written as a
NUL-terminated string to
buf, where at most
buf_len bytes are
written, truncating the result if necessary. In any case it returns the total
string length, excluding the NUL character, required for non-truncated
representation, or -1 on error. 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_add_sigid() creates a new composite "Signature Algorithm"
that associates a given NID with two other NIDs - one representing the
underlying signature algorithm and the other representing a digest algorithm
to be used in conjunction with it.
signid represents the NID for the
composite "Signature Algorithm",
dig_id is the NID for the
digest algorithm and
pkey_id is the NID for the underlying signature
algorithm. As there are signature algorithms that do not require a digest,
NID_undef is a valid
dig_id.
OBJ_cleanup() releases any resources allocated by creating new objects.
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.
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.
OBJ_add_sigid() returns 1 on success or 0 on error.
i2t_ASN1_OBJECT() an
OBJ_obj2txt() return -1 on error. On success,
they return the length of the string written to
buf if
buf is
not NULL and
buf_len is big enough, otherwise the total string length.
Note that this does not count the trailing NUL character.
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);
Neither
OBJ_create() nor
OBJ_add_sigid() do any locking and are
thus not thread safe. Moreover, none of the other functions should be called
while concurrent calls to these two functions are possible.
ERR_get_error(3)
OBJ_cleanup() was deprecated in OpenSSL 1.1.0 by
OPENSSL_init_crypto(3) and should not be used.
Copyright 2002-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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>.