1=pod 2 3=head1 NAME 4 5i2t_ASN1_OBJECT, 6OBJ_length, OBJ_get0_data, OBJ_nid2obj, OBJ_nid2ln, 7OBJ_nid2sn, OBJ_obj2nid, OBJ_txt2nid, OBJ_ln2nid, OBJ_sn2nid, OBJ_cmp, 8OBJ_dup, OBJ_txt2obj, OBJ_obj2txt, OBJ_create, OBJ_cleanup, OBJ_add_sigid 9- ASN1 object utility functions 10 11=head1 SYNOPSIS 12 13 #include <openssl/objects.h> 14 15 ASN1_OBJECT *OBJ_nid2obj(int n); 16 const char *OBJ_nid2ln(int n); 17 const char *OBJ_nid2sn(int n); 18 19 int OBJ_obj2nid(const ASN1_OBJECT *o); 20 int OBJ_ln2nid(const char *ln); 21 int OBJ_sn2nid(const char *sn); 22 23 int OBJ_txt2nid(const char *s); 24 25 ASN1_OBJECT *OBJ_txt2obj(const char *s, int no_name); 26 int OBJ_obj2txt(char *buf, int buf_len, const ASN1_OBJECT *a, int no_name); 27 28 int i2t_ASN1_OBJECT(char *buf, int buf_len, const ASN1_OBJECT *a); 29 30 int OBJ_cmp(const ASN1_OBJECT *a, const ASN1_OBJECT *b); 31 ASN1_OBJECT *OBJ_dup(const ASN1_OBJECT *o); 32 33 int OBJ_create(const char *oid, const char *sn, const char *ln); 34 35 size_t OBJ_length(const ASN1_OBJECT *obj); 36 const unsigned char *OBJ_get0_data(const ASN1_OBJECT *obj); 37 38 int OBJ_add_sigid(int signid, int dig_id, int pkey_id); 39 40Deprecated since OpenSSL 1.1.0, can be hidden entirely by defining 41B<OPENSSL_API_COMPAT> with a suitable version value, see 42L<openssl_user_macros(7)>: 43 44 void OBJ_cleanup(void); 45 46=head1 DESCRIPTION 47 48The ASN1 object utility functions process ASN1_OBJECT structures which are 49a representation of the ASN1 OBJECT IDENTIFIER (OID) type. 50For convenience, OIDs are usually represented in source code as numeric 51identifiers, or B<NID>s. OpenSSL has an internal table of OIDs that 52are generated when the library is built, and their corresponding NIDs 53are available as defined constants. For the functions below, application 54code should treat all returned values -- OIDs, NIDs, or names -- as 55constants. 56 57OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID I<n> to 58an ASN1_OBJECT structure, its long name and its short name respectively, 59or B<NULL> if an error occurred. 60 61OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() return the corresponding NID 62for the object I<o>, the long name I<ln> or the short name I<sn> respectively 63or NID_undef if an error occurred. 64 65OBJ_txt2nid() returns NID corresponding to text string I<s>. I<s> can be 66a long name, a short name or the numerical representation of an object. 67 68OBJ_txt2obj() converts the text string I<s> into an ASN1_OBJECT structure. 69If I<no_name> is 0 then long names and short names will be interpreted 70as well as numerical forms. If I<no_name> is 1 only the numerical form 71is acceptable. 72 73OBJ_obj2txt() converts the B<ASN1_OBJECT> I<a> into a textual representation. 74The representation is written as a null terminated string to I<buf> 75at most I<buf_len> bytes are written, truncating the result if necessary. 76The total amount of space required is returned. If I<no_name> is 0 then 77if the object has a long or short name then that will be used, otherwise 78the numerical form will be used. If I<no_name> is 1 then the numerical 79form will always be used. 80 81i2t_ASN1_OBJECT() is the same as OBJ_obj2txt() with the I<no_name> set to zero. 82 83OBJ_cmp() compares I<a> to I<b>. If the two are identical 0 is returned. 84 85OBJ_dup() returns a copy of I<o>. 86 87OBJ_create() adds a new object to the internal table. I<oid> is the 88numerical form of the object, I<sn> the short name and I<ln> the 89long name. A new NID is returned for the created object in case of 90success and NID_undef in case of failure. 91 92OBJ_length() returns the size of the content octets of I<obj>. 93 94OBJ_get0_data() returns a pointer to the content octets of I<obj>. 95The returned pointer is an internal pointer which B<must not> be freed. 96 97OBJ_add_sigid() creates a new composite "Signature Algorithm" that associates a 98given NID with two other NIDs - one representing the underlying signature 99algorithm and the other representing a digest algorithm to be used in 100conjunction with it. I<signid> represents the NID for the composite "Signature 101Algorithm", I<dig_id> is the NID for the digest algorithm and I<pkey_id> is the 102NID for the underlying signature algorithm. 103 104OBJ_cleanup() releases any resources allocated by creating new objects. 105 106=head1 NOTES 107 108Objects in OpenSSL can have a short name, a long name and a numerical 109identifier (NID) associated with them. A standard set of objects is 110represented in an internal table. The appropriate values are defined 111in the header file B<objects.h>. 112 113For example the OID for commonName has the following definitions: 114 115 #define SN_commonName "CN" 116 #define LN_commonName "commonName" 117 #define NID_commonName 13 118 119New objects can be added by calling OBJ_create(). 120 121Table objects have certain advantages over other objects: for example 122their NIDs can be used in a C language switch statement. They are 123also static constant structures which are shared: that is there 124is only a single constant structure for each table object. 125 126Objects which are not in the table have the NID value NID_undef. 127 128Objects do not need to be in the internal tables to be processed, 129the functions OBJ_txt2obj() and OBJ_obj2txt() can process the numerical 130form of an OID. 131 132Some objects are used to represent algorithms which do not have a 133corresponding ASN.1 OBJECT IDENTIFIER encoding (for example no OID currently 134exists for a particular algorithm). As a result they B<cannot> be encoded or 135decoded as part of ASN.1 structures. Applications can determine if there 136is a corresponding OBJECT IDENTIFIER by checking OBJ_length() is not zero. 137 138These functions cannot return B<const> because an B<ASN1_OBJECT> can 139represent both an internal, constant, OID and a dynamically-created one. 140The latter cannot be constant because it needs to be freed after use. 141 142=head1 RETURN VALUES 143 144OBJ_nid2obj() returns an B<ASN1_OBJECT> structure or B<NULL> is an 145error occurred. 146 147OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or B<NULL> 148on error. 149 150OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return 151a NID or B<NID_undef> on error. 152 153OBJ_add_sigid() returns 1 on success or 0 on error. 154 155=head1 EXAMPLES 156 157Create an object for B<commonName>: 158 159 ASN1_OBJECT *o = OBJ_nid2obj(NID_commonName); 160 161Check if an object is B<commonName> 162 163 if (OBJ_obj2nid(obj) == NID_commonName) 164 /* Do something */ 165 166Create a new NID and initialize an object from it: 167 168 int new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier"); 169 ASN1_OBJECT *obj = OBJ_nid2obj(new_nid); 170 171Create a new object directly: 172 173 obj = OBJ_txt2obj("1.2.3.4", 1); 174 175=head1 BUGS 176 177OBJ_obj2txt() is awkward and messy to use: it doesn't follow the 178convention of other OpenSSL functions where the buffer can be set 179to B<NULL> to determine the amount of data that should be written. 180Instead I<buf> must point to a valid buffer and I<buf_len> should 181be set to a positive value. A buffer length of 80 should be more 182than enough to handle any OID encountered in practice. 183 184Neither OBJ_create() nor OBJ_add_sigid() do any locking and are thus not 185thread safe. Moreover, none of the other functions should be called while 186concurrent calls to these two functions are possible. 187 188=head1 SEE ALSO 189 190L<ERR_get_error(3)> 191 192=head1 HISTORY 193 194OBJ_cleanup() was deprecated in OpenSSL 1.1.0 by L<OPENSSL_init_crypto(3)> 195and should not be used. 196 197=head1 COPYRIGHT 198 199Copyright 2002-2021 The OpenSSL Project Authors. All Rights Reserved. 200 201Licensed under the Apache License 2.0 (the "License"). You may not use 202this file except in compliance with the License. You can obtain a copy 203in the file LICENSE in the source distribution or at 204L<https://www.openssl.org/source/license.html>. 205 206=cut 207