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 40The following function has been deprecated since OpenSSL 1.1.0, and can be 41hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, 42see L<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. 74Unless I<buf> is NULL, 75the representation is written as a NUL-terminated string to I<buf>, where 76at most I<buf_len> bytes are written, truncating the result if necessary. 77In any case it returns the total string length, excluding the NUL character, 78required for non-truncated representation, or -1 on error. 79If I<no_name> is 0 then if the object has a long or short name 80then that will be used, otherwise the numerical form will be used. 81If I<no_name> is 1 then the numerical form will always be used. 82 83i2t_ASN1_OBJECT() is the same as OBJ_obj2txt() with the I<no_name> set to zero. 84 85OBJ_cmp() compares I<a> to I<b>. If the two are identical 0 is returned. 86 87OBJ_dup() returns a copy of I<o>. 88 89OBJ_create() adds a new object to the internal table. I<oid> is the 90numerical form of the object, I<sn> the short name and I<ln> the 91long name. A new NID is returned for the created object in case of 92success and NID_undef in case of failure. 93 94OBJ_length() returns the size of the content octets of I<obj>. 95 96OBJ_get0_data() returns a pointer to the content octets of I<obj>. 97The returned pointer is an internal pointer which B<must not> be freed. 98 99OBJ_add_sigid() creates a new composite "Signature Algorithm" that associates a 100given NID with two other NIDs - one representing the underlying signature 101algorithm and the other representing a digest algorithm to be used in 102conjunction with it. I<signid> represents the NID for the composite "Signature 103Algorithm", I<dig_id> is the NID for the digest algorithm and I<pkey_id> is the 104NID for the underlying signature algorithm. As there are signature algorithms 105that do not require a digest, NID_undef is a valid I<dig_id>. 106 107OBJ_cleanup() releases any resources allocated by creating new objects. 108 109=head1 NOTES 110 111Objects in OpenSSL can have a short name, a long name and a numerical 112identifier (NID) associated with them. A standard set of objects is 113represented in an internal table. The appropriate values are defined 114in the header file B<objects.h>. 115 116For example the OID for commonName has the following definitions: 117 118 #define SN_commonName "CN" 119 #define LN_commonName "commonName" 120 #define NID_commonName 13 121 122New objects can be added by calling OBJ_create(). 123 124Table objects have certain advantages over other objects: for example 125their NIDs can be used in a C language switch statement. They are 126also static constant structures which are shared: that is there 127is only a single constant structure for each table object. 128 129Objects which are not in the table have the NID value NID_undef. 130 131Objects do not need to be in the internal tables to be processed, 132the functions OBJ_txt2obj() and OBJ_obj2txt() can process the numerical 133form of an OID. 134 135Some objects are used to represent algorithms which do not have a 136corresponding ASN.1 OBJECT IDENTIFIER encoding (for example no OID currently 137exists for a particular algorithm). As a result they B<cannot> be encoded or 138decoded as part of ASN.1 structures. Applications can determine if there 139is a corresponding OBJECT IDENTIFIER by checking OBJ_length() is not zero. 140 141These functions cannot return B<const> because an B<ASN1_OBJECT> can 142represent both an internal, constant, OID and a dynamically-created one. 143The latter cannot be constant because it needs to be freed after use. 144 145=head1 RETURN VALUES 146 147OBJ_nid2obj() returns an B<ASN1_OBJECT> structure or B<NULL> is an 148error occurred. 149 150OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or B<NULL> 151on error. 152 153OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return 154a NID or B<NID_undef> on error. 155 156OBJ_add_sigid() returns 1 on success or 0 on error. 157 158i2t_ASN1_OBJECT() an OBJ_obj2txt() return -1 on error. 159On success, they return the length of the string written to I<buf> if I<buf> is 160not NULL and I<buf_len> is big enough, otherwise the total string length. 161Note that this does not count the trailing NUL character. 162 163=head1 EXAMPLES 164 165Create an object for B<commonName>: 166 167 ASN1_OBJECT *o = OBJ_nid2obj(NID_commonName); 168 169Check if an object is B<commonName> 170 171 if (OBJ_obj2nid(obj) == NID_commonName) 172 /* Do something */ 173 174Create a new NID and initialize an object from it: 175 176 int new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier"); 177 ASN1_OBJECT *obj = OBJ_nid2obj(new_nid); 178 179Create a new object directly: 180 181 obj = OBJ_txt2obj("1.2.3.4", 1); 182 183=head1 BUGS 184 185Neither OBJ_create() nor OBJ_add_sigid() do any locking and are thus not 186thread safe. Moreover, none of the other functions should be called while 187concurrent calls to these two functions are possible. 188 189=head1 SEE ALSO 190 191L<ERR_get_error(3)> 192 193=head1 HISTORY 194 195OBJ_cleanup() was deprecated in OpenSSL 1.1.0 by L<OPENSSL_init_crypto(3)> 196and should not be used. 197 198=head1 COPYRIGHT 199 200Copyright 2002-2021 The OpenSSL Project Authors. All Rights Reserved. 201 202Licensed under the Apache License 2.0 (the "License"). You may not use 203this file except in compliance with the License. You can obtain a copy 204in the file LICENSE in the source distribution or at 205L<https://www.openssl.org/source/license.html>. 206 207=cut 208