OBJ_nid2obj(3) OpenSSL OBJ_nid2obj(3) NNAAMMEE 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 SSYYNNOOPPSSIISS #include 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); DDEESSCCRRIIPPTTIIOONN 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 NNIIDDs. 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. _O_B_J___n_i_d_2_o_b_j_(_), _O_B_J___n_i_d_2_l_n_(_) and _O_B_J___n_i_d_2_s_n_(_) convert the NID nn to an ASN1_OBJECT structure, its long name and its short name respectively, or NNUULLLL if an error occurred. _O_B_J___o_b_j_2_n_i_d_(_), _O_B_J___l_n_2_n_i_d_(_), _O_B_J___s_n_2_n_i_d_(_) return the corresponding NID for the object oo, the long name or the short name respec- tively or NID_undef if an error occurred. _O_B_J___t_x_t_2_n_i_d_(_) returns NID corresponding to text string . ss can be a long name, a short name or the numerical respresentation of an object. _O_B_J___t_x_t_2_o_b_j_(_) converts the text string ss into an ASN1_OBJECT structure. If nnoo__nnaammee is 0 then long names and short names will be interpreted as well as numerical forms. If nnoo__nnaammee is 1 only the numerical form is acceptable. _O_B_J___o_b_j_2_t_x_t_(_) converts the AASSNN11__OOBBJJEECCTT aa into a textual representation. The representation is written as a null terminated string to bbuuff at most bbuuff__lleenn bytes are written, truncating the result if necessary. The total amount of space required is returned. If nnoo__nnaammee 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 nnoo__nnaammee is 1 then the numerical form will always be used. _O_B_J___c_m_p_(_) compares aa to bb. If the two are identical 0 is returned. _O_B_J___d_u_p_(_) returns a copy of oo. _O_B_J___c_r_e_a_t_e_(_) adds a new object to the internal table. ooiidd is the numer- ical form of the object, ssnn the short name and llnn the long name. A new NID is returned for the created object. _O_B_J___c_l_e_a_n_u_p_(_) cleans up OpenSSLs internal object table: this should be called before an application exits if any new objects were added using _O_B_J___c_r_e_a_t_e_(_). NNOOTTEESS 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 oobbjjeeccttss..hh. 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 _O_B_J___c_r_e_a_t_e_(_). 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 _O_B_J___t_x_t_2_o_b_j_(_) and _O_B_J___o_b_j_2_t_x_t_(_) can process the numerical form of an OID. Some objects are used to represent algorithms which do not have a cor- responding ASN.1 OBJECT IDENTIFIER encoding (for example no OID cur- rently exists for a particular algorithm). As a result they ccaannnnoott be encoded or decoded as part of ASN.1 structures. Applications can deter- mine if there is a corresponding OBJECT IDENTIFIER by checking _O_B_J___l_e_n_g_t_h_(_) is not zero. These functions cannot return ccoonnsstt because an AASSNN11__OOBBJJEECCTT can repre- sent both an internal, constant, OID and a dynamically-created one. The latter cannot be constant because it needs to be freed after use. EEXXAAMMPPLLEESS Create an object for ccoommmmoonnNNaammee: ASN1_OBJECT *o; o = OBJ_nid2obj(NID_commonName); Check if an object is ccoommmmoonnNNaammee 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("1.2.3.4", "NewOID", "New Object Identifier"); obj = OBJ_nid2obj(new_nid); Create a new object directly: obj = OBJ_txt2obj("1.2.3.4", 1); BBUUGGSS _O_B_J___o_b_j_2_t_x_t_(_) is awkward and messy to use: it doesn't follow the con- vention of other OpenSSL functions where the buffer can be set to NNUULLLL to determine the amount of data that should be written. Instead bbuuff must point to a valid buffer and bbuuff__lleenn should be set to a positive value. A buffer length of 80 should be more than enough to handle any OID encountered in practice. RREETTUURRNN VVAALLUUEESS _O_B_J___n_i_d_2_o_b_j_(_) returns an AASSNN11__OOBBJJEECCTT structure or NNUULLLL is an error occurred. It returns a pointer to an internal table and does not allo- cate memory; _A_S_N_1___O_B_J_E_C_T___f_r_e_e_(_) will have no effect. _O_B_J___n_i_d_2_l_n_(_) and _O_B_J___n_i_d_2_s_n_(_) returns a valid string or NNUULLLL on error. _O_B_J___o_b_j_2_n_i_d_(_), _O_B_J___l_n_2_n_i_d_(_), _O_B_J___s_n_2_n_i_d_(_) and _O_B_J___t_x_t_2_n_i_d_(_) return a NID or NNIIDD__uunnddeeff on error. SSEEEE AALLSSOO _E_R_R___g_e_t___e_r_r_o_r(3) HHIISSTTOORRYY TBA 1.0.2u 2019-12-20 OBJ_nid2obj(3)