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Libtasn1
********
This manual is for GNU Libtasn1 (version 4.10, 4 April 2016), which is a
library for Abstract Syntax Notation One (ASN.1) and Distinguished
Encoding Rules (DER) manipulation.
Copyright (C) 2001-2015 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, no Front-Cover Texts, and
no Back-Cover Texts. A copy of the license is included in the
section entitled "GNU Free Documentation License".
* Menu:
* Introduction::
* ASN.1 structure handling::
* Utilities::
* Function reference::
* Copying Information::
Indices
* Concept Index:: Index of concepts and programs.
* Function and Data Index:: Index of functions, variables and data types.
File: libtasn1.info, Node: Introduction, Next: ASN.1 structure handling, Prev: Top, Up: Top
1 Introduction
**************
This document describes the Libtasn1 library that provides Abstract
Syntax Notation One (ASN.1, as specified by the X.680 ITU-T
recommendation) parsing and structures management, and Distinguished
Encoding Rules (DER, as per X.690) encoding and decoding functions.
The main features of this library are:
* On-line ASN.1 structure management that doesn't require any C code
file generation.
* Off-line ASN.1 structure management with C code file generation
containing an array.
* Distinguished Encoding Rules (DER) encoding support.
* No limits for INTEGER and ENUMERATED values.
* It's Free Software. Anybody can use, modify, and redistribute the
library under the terms of the GNU Lesser General Public License
version 2.1 or later. The command line tools, self-tests and build
infrastructure are licensed under the GNU General Public License
version 3.0 or later.
* Thread-safety. No global variables are used and multiple library
handles and session handles may be used in parallel.
* Portability. The code should work on all Unix like operating
systems, and Windows. The library itself should be portable to any
C89 system, not even POSIX is required.
File: libtasn1.info, Node: ASN.1 structure handling, Next: Utilities, Prev: Introduction, Up: Top
2 ASN.1 structure handling
**************************
* Menu:
* ASN.1 syntax::
* Naming::
* Simple parsing::
* Library Notes::
* Future developments::
File: libtasn1.info, Node: ASN.1 syntax, Next: Naming, Up: ASN.1 structure handling
2.1 ASN.1 syntax
================
The parser is case sensitive. The comments begin with '--' and end
either with another '--', or at the end of the respective line,
whichever comes first. The C-style '/*', '*/' comments are not
supported.
For an example of the syntax, check the 'pkix.asn' file distributed
with the library.
ASN.1 definitions must follow the syntax below:
definitions_name {<object definition>}
DEFINITIONS <EXPLICIT or IMPLICIT> TAGS ::=
BEGIN
<type and constants definitions>
END
The '::=' token must be separate from other elements, so the
following declaration is invalid:
-- INCORRECT
Version ::=INTEGER
The correct form is:
Version ::= INTEGER
Here is the list of types that the parser can manage:
* 'INTEGER';
* 'ENUMERATED';
* 'BOOLEAN';
* 'OBJECT IDENTIFIER';
* 'NULL';
* 'BIT STRING';
* 'OCTET STRING';
* 'UTCTime';
* 'GeneralizedTime';
* 'GeneralString';
* 'NumericString';
* 'IA5String';
* 'TeletexString';
* 'PrintableString';
* 'UniversalString';
* 'BMPString';
* 'UTF8String';
* 'VisibleString';
* 'SEQUENCE';
* 'SEQUENCE OF';
* 'SET';
* 'SET OF';
* 'CHOICE';
* 'ANY';
* 'ANY DEFINED BY'.
This version doesn't handle the 'REAL' type. It doesn't support the
'AUTOMATIC TAGS' option, and the 'EXPORT' and 'IMPORT' sections, either.
The 'SIZE' constraints are allowed, but no check is done on them.
File: libtasn1.info, Node: Naming, Next: Simple parsing, Prev: ASN.1 syntax, Up: ASN.1 structure handling
2.2 Naming
==========
Consider this definition:
Example { 1 2 3 4 }
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
Group ::= SEQUENCE {
id OBJECT IDENTIFIER,
value Value
}
Value ::= SEQUENCE {
value1 INTEGER,
value2 BOOLEAN
}
END
The notation to access the 'Group' type of the 'Example' definition
above is 'Example.Group' (as a NUL-terminated string.) Such strings are
used in the functions described below.
Others examples:
* field 'id' of the 'Group' type: 'Example.Group.id';
* field 'value1' of the 'value' field of the 'Group' type:
'Example.Group.value.value1'.
Elements of structured types unnamed by the respective definition
receive the names '?1', '?2', and so on.
The '?LAST' name indicates the last element of a 'SET OF' or
'SEQUENCE OF'.
File: libtasn1.info, Node: Simple parsing, Next: Library Notes, Prev: Naming, Up: ASN.1 structure handling
2.3 Simple parsing
==================
For simple types like 'OCTET STRING' the simple parsing functions listed
below may be used instead.
* *note asn1_decode_simple_der::
* *note asn1_encode_simple_der::
File: libtasn1.info, Node: Library Notes, Next: Future developments, Prev: Simple parsing, Up: ASN.1 structure handling
2.4 Library Notes
=================
The header file of this library is 'libtasn1.h'.
The main type used in it is 'asn1_node', and it's used to store the
ASN.1 definitions and structures (instances).
The 'NULL' constant can be used for the variable initialization. For
example:
asn1_node definitions = NULL;
Some functions require an 'errorDescription' argument of type 'char
*', pointing to a pre-allocated buffer of at least
'ASN1_MAX_ERROR_DESCRIPTION_SIZE' bytes size (e.g., as in 'char
description[ASN1_MAX_ERROR_DESCRIPTION_SIZE];').
'ASN1_MAX_NAME_SIZE' is the maximum number of characters allowed for
an ASN.1 identifier.
File: libtasn1.info, Node: Future developments, Prev: Library Notes, Up: ASN.1 structure handling
2.5 Future developments
=======================
* Add functions for a C code file generation containing equivalent
data structures (not a single array like now).
* The 'REAL' type.
File: libtasn1.info, Node: Utilities, Next: Function reference, Prev: ASN.1 structure handling, Up: Top
3 Utilities
***********
* Menu:
* Invoking asn1Parser::
* Invoking asn1Coding::
* Invoking asn1Decoding::
File: libtasn1.info, Node: Invoking asn1Parser, Next: Invoking asn1Coding, Up: Utilities
3.1 Invoking asn1Parser
=======================
'asn1Parser' reads a single file with ASN.1 definitions and generates a
file with an array to use with libtasn1 functions.
Usage: asn1Parser [options] file
Options:
-h : shows the help message.
-v : shows version information and exit.
-c : checks the syntax only.
-o file : output file.
-n name : array name.
File: libtasn1.info, Node: Invoking asn1Coding, Next: Invoking asn1Decoding, Prev: Invoking asn1Parser, Up: Utilities
3.2 Invoking asn1Coding
=======================
'asn1Coding' generates a DER encoding from a file with ASN.1 definitions
and another one with assignments.
The file with assignments must have this syntax:
InstanceName Asn1Definition
nameString value
nameString value
...
To specify the field of a 'CHOICE' to be used, specify its name as a
value to the 'CHOICE' element itself. Use '''' to denote the root
element itself. (as in the example below.)
The output file is a binary file with the DER encoding.
Usage: asn1Coding [options] file1 file2
file1 : file with ASN1 definitions.
file2 : file with assignments.
Options:
-h : shows the help message.
-v : shows version information and exit.
-c : checks the syntax only.
-o file : output file.
For example, consider an ASN.1 definitions file as follows:
MYPKIX1 { }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
OtherStruct := SEQUENCE {
x INTEGER,
y CHOICE {
y1 INTEGER,
y2 OCTET STRING },
}
Dss-Sig-Value ::= SEQUENCE {
r INTEGER,
s INTEGER,
other OtherStruct
z INTEGER OPTIONAL,
}
END
And a assignments file as follows:
dp MYPKIX1.Dss-Sig-Value
r 42
s 47
other.x 66
other.y y1
other.y.y1 15
z (NULL)
Running the command below will generate a 'assign.out' file,
containing the DER encoding of 'PKIX1.Dss-Sig-Value'.
$ asn1Coding pkix.asn assign.asn1
If the root element is of the 'CHOICE' type, the assignment file may
be like (using the types defined in 'pkix.asn'):
elt PKIX1Implicit88.GeneralName
'' dNSName
dNSName example.org
File: libtasn1.info, Node: Invoking asn1Decoding, Prev: Invoking asn1Coding, Up: Utilities
3.3 Invoking asn1Decoding
=========================
'asn1Decoding' generates an ASN.1 structure from a file with ASN.1
definitions and a binary file with a DER encoding.
Usage: asn1Decoding [options] file1 file2 type
file1 : file with ASN1 definitions.
file2 : binary file with a DER encoding.
type : ASN1 definition name.
Options:
-h : shows the help message.
-v : shows version information and exit.
-o file : output file.
For example, after generating the 'assign.out' file from the example
section of the 'asn1Coding' command above, the following invocation will
decode the DER data.
$ asn1Decoding pkix.asn assign.out PKIX1.Dss-Sig-Value
File: libtasn1.info, Node: Function reference, Next: Copying Information, Prev: Utilities, Up: Top
4 Function reference
********************
* Menu:
* ASN.1 schema functions::
* ASN.1 field functions::
* DER functions::
* Error handling functions::
* Auxilliary functions::
File: libtasn1.info, Node: ASN.1 schema functions, Next: ASN.1 field functions, Up: Function reference
4.1 ASN.1 schema functions
==========================
asn1_parser2tree
----------------
-- Function: int asn1_parser2tree (const char * FILE, asn1_node *
DEFINITIONS, char * ERROR_DESC)
FILE: specify the path and the name of file that contains ASN.1
declarations.
DEFINITIONS: return the pointer to the structure created from
"file" ASN.1 declarations.
ERROR_DESC: return the error description or an empty string if
success.
Function used to start the parse algorithm. Creates the structures
needed to manage the definitions included in 'file' file.
*Returns:* 'ASN1_SUCCESS' if the file has a correct syntax and
every identifier is known, 'ASN1_ELEMENT_NOT_EMPTY' if
'definitions' not 'NULL' , 'ASN1_FILE_NOT_FOUND' if an error
occured while opening 'file' , 'ASN1_SYNTAX_ERROR' if the syntax is
not correct, 'ASN1_IDENTIFIER_NOT_FOUND' if in the file there is an
identifier that is not defined, 'ASN1_NAME_TOO_LONG' if in the file
there is an identifier whith more than 'ASN1_MAX_NAME_SIZE'
characters.
asn1_parser2array
-----------------
-- Function: int asn1_parser2array (const char * INPUTFILENAME, const
char * OUTPUTFILENAME, const char * VECTORNAME, char *
ERROR_DESC)
INPUTFILENAME: specify the path and the name of file that contains
ASN.1 declarations.
OUTPUTFILENAME: specify the path and the name of file that will
contain the C vector definition.
VECTORNAME: specify the name of the C vector.
ERROR_DESC: return the error description or an empty string if
success.
Function that generates a C structure from an ASN1 file. Creates a
file containing a C vector to use to manage the definitions
included in 'inputFileName' file. If 'inputFileName' is
"/aa/bb/xx.yy" and 'outputFileName' is 'NULL' , the file created is
"/aa/bb/xx_asn1_tab.c". If 'vectorName' is 'NULL' the vector name
will be "xx_asn1_tab".
*Returns:* 'ASN1_SUCCESS' if the file has a correct syntax and
every identifier is known, 'ASN1_FILE_NOT_FOUND' if an error
occured while opening 'inputFileName' , 'ASN1_SYNTAX_ERROR' if the
syntax is not correct, 'ASN1_IDENTIFIER_NOT_FOUND' if in the file
there is an identifier that is not defined, 'ASN1_NAME_TOO_LONG' if
in the file there is an identifier whith more than
'ASN1_MAX_NAME_SIZE' characters.
File: libtasn1.info, Node: ASN.1 field functions, Next: DER functions, Prev: ASN.1 schema functions, Up: Function reference
4.2 ASN.1 field functions
=========================
asn1_array2tree
---------------
-- Function: int asn1_array2tree (const asn1_static_node * ARRAY,
asn1_node * DEFINITIONS, char * ERRORDESCRIPTION)
ARRAY: specify the array that contains ASN.1 declarations
DEFINITIONS: return the pointer to the structure created by *ARRAY
ASN.1 declarations
ERRORDESCRIPTION: return the error description.
Creates the structures needed to manage the ASN.1 definitions.
'array' is a vector created by 'asn1_parser2array()' .
*Returns:* 'ASN1_SUCCESS' if structure was created correctly,
'ASN1_ELEMENT_NOT_EMPTY' if * 'definitions' not NULL,
'ASN1_IDENTIFIER_NOT_FOUND' if in the file there is an identifier
that is not defined (see 'errorDescription' for more information),
'ASN1_ARRAY_ERROR' if the array pointed by 'array' is wrong.
asn1_delete_structure
---------------------
-- Function: int asn1_delete_structure (asn1_node * STRUCTURE)
STRUCTURE: pointer to the structure that you want to delete.
Deletes the structure * 'structure' . At the end, * 'structure' is
set to NULL.
*Returns:* 'ASN1_SUCCESS' if successful, 'ASN1_ELEMENT_NOT_FOUND'
if * 'structure' was NULL.
asn1_delete_structure2
----------------------
-- Function: int asn1_delete_structure2 (asn1_node * STRUCTURE,
unsigned int FLAGS)
STRUCTURE: pointer to the structure that you want to delete.
FLAGS: additional flags (see 'ASN1_DELETE_FLAG' )
Deletes the structure * 'structure' . At the end, * 'structure' is
set to NULL.
*Returns:* 'ASN1_SUCCESS' if successful, 'ASN1_ELEMENT_NOT_FOUND'
if * 'structure' was NULL.
asn1_delete_element
-------------------
-- Function: int asn1_delete_element (asn1_node STRUCTURE, const char *
ELEMENT_NAME)
STRUCTURE: pointer to the structure that contains the element you
want to delete.
ELEMENT_NAME: element's name you want to delete.
Deletes the element named * 'element_name' inside * 'structure' .
*Returns:* 'ASN1_SUCCESS' if successful, 'ASN1_ELEMENT_NOT_FOUND'
if the 'element_name' was not found.
asn1_create_element
-------------------
-- Function: int asn1_create_element (asn1_node DEFINITIONS, const char
* SOURCE_NAME, asn1_node * ELEMENT)
DEFINITIONS: pointer to the structure returned by "parser_asn1"
function
SOURCE_NAME: the name of the type of the new structure (must be
inside p_structure).
ELEMENT: pointer to the structure created.
Creates a structure of type 'source_name' . Example using
"pkix.asn":
rc = asn1_create_element(cert_def, "PKIX1.Certificate", certptr);
*Returns:* 'ASN1_SUCCESS' if creation OK, 'ASN1_ELEMENT_NOT_FOUND'
if 'source_name' is not known.
asn1_print_structure
--------------------
-- Function: void asn1_print_structure (FILE * OUT, asn1_node
STRUCTURE, const char * NAME, int MODE)
OUT: pointer to the output file (e.g. stdout).
STRUCTURE: pointer to the structure that you want to visit.
NAME: an element of the structure
MODE: specify how much of the structure to print, can be
'ASN1_PRINT_NAME' , 'ASN1_PRINT_NAME_TYPE' ,
'ASN1_PRINT_NAME_TYPE_VALUE' , or 'ASN1_PRINT_ALL' .
Prints on the 'out' file descriptor the structure's tree starting
from the 'name' element inside the structure 'structure' .
asn1_number_of_elements
-----------------------
-- Function: int asn1_number_of_elements (asn1_node ELEMENT, const char
* NAME, int * NUM)
ELEMENT: pointer to the root of an ASN1 structure.
NAME: the name of a sub-structure of ROOT.
NUM: pointer to an integer where the result will be stored
Counts the number of elements of a sub-structure called NAME with
names equal to "?1","?2", ...
*Returns:* 'ASN1_SUCCESS' if successful, 'ASN1_ELEMENT_NOT_FOUND'
if 'name' is not known, 'ASN1_GENERIC_ERROR' if pointer 'num' is
'NULL' .
asn1_find_structure_from_oid
----------------------------
-- Function: const char * asn1_find_structure_from_oid (asn1_node
DEFINITIONS, const char * OIDVALUE)
DEFINITIONS: ASN1 definitions
OIDVALUE: value of the OID to search (e.g. "1.2.3.4").
Search the structure that is defined just after an OID definition.
*Returns:* 'NULL' when 'oidValue' not found, otherwise the pointer
to a constant string that contains the element name defined just
after the OID.
asn1_copy_node
--------------
-- Function: int asn1_copy_node (asn1_node DST, const char * DST_NAME,
asn1_node SRC, const char * SRC_NAME)
DST: Destination asn1 node.
DST_NAME: Field name in destination node.
SRC: Source asn1 node.
SRC_NAME: Field name in source node.
Create a deep copy of a asn1_node variable. That function requires
'dst' to be expanded using 'asn1_create_element()' .
*Returns:* Return 'ASN1_SUCCESS' on success.
asn1_dup_node
-------------
-- Function: asn1_node asn1_dup_node (asn1_node SRC, const char *
SRC_NAME)
SRC: Source asn1 node.
SRC_NAME: Field name in source node.
Create a deep copy of a asn1_node variable. This function will
return an exact copy of the provided structure.
*Returns:* Return 'NULL' on failure.
asn1_write_value
----------------
-- Function: int asn1_write_value (asn1_node NODE_ROOT, const char *
NAME, const void * IVALUE, int LEN)
NODE_ROOT: pointer to a structure
NAME: the name of the element inside the structure that you want to
set.
IVALUE: vector used to specify the value to set. If len is >0,
VALUE must be a two's complement form integer. if len=0 *VALUE
must be a null terminated string with an integer value.
LEN: number of bytes of *value to use to set the value:
value[0]..value[len-1] or 0 if value is a null terminated string
Set the value of one element inside a structure.
If an element is OPTIONAL and you want to delete it, you must use
the value=NULL and len=0. Using "pkix.asn":
result=asn1_write_value(cert, "tbsCertificate.issuerUniqueID",
NULL, 0);
Description for each type:
*INTEGER:* VALUE must contain a two's complement form integer.
value[0]=0xFF , len=1 -> integer=-1. value[0]=0xFF value[1]=0xFF ,
len=2 -> integer=-1. value[0]=0x01 , len=1 -> integer= 1.
value[0]=0x00 value[1]=0x01 , len=2 -> integer= 1. value="123" ,
len=0 -> integer= 123.
*ENUMERATED:* As INTEGER (but only with not negative numbers).
*BOOLEAN:* VALUE must be the null terminated string "TRUE" or
"FALSE" and LEN != 0.
value="TRUE" , len=1 -> boolean=TRUE. value="FALSE" , len=1 ->
boolean=FALSE.
OBJECT IDENTIFIER: VALUE must be a null terminated string with each
number separated by a dot (e.g. "1.2.3.543.1"). LEN != 0.
value="1 2 840 10040 4 3" , len=1 -> OID=dsa-with-sha.
*UTCTime:* VALUE must be a null terminated string in one of these
formats: "YYMMDDhhmmssZ", "YYMMDDhhmmssZ", "YYMMDDhhmmss+hh'mm'",
"YYMMDDhhmmss-hh'mm'", "YYMMDDhhmm+hh'mm'", or "YYMMDDhhmm-hh'mm'".
LEN != 0.
value="9801011200Z" , len=1 -> time=Jannuary 1st, 1998 at 12h 00m
Greenwich Mean Time
*GeneralizedTime:* VALUE must be in one of this format:
"YYYYMMDDhhmmss.sZ", "YYYYMMDDhhmmss.sZ",
"YYYYMMDDhhmmss.s+hh'mm'", "YYYYMMDDhhmmss.s-hh'mm'",
"YYYYMMDDhhmm+hh'mm'", or "YYYYMMDDhhmm-hh'mm'" where ss.s
indicates the seconds with any precision like "10.1" or "01.02".
LEN != 0
value="2001010112001.12-0700" , len=1 -> time=Jannuary 1st, 2001 at
12h 00m 01.12s Pacific Daylight Time
OCTET STRING: VALUE contains the octet string and LEN is the number
of octets.
value="$\backslash$x01$\backslash$x02$\backslash$x03" , len=3 ->
three bytes octet string
*GeneralString:* VALUE contains the generalstring and LEN is the
number of octets.
value="$\backslash$x01$\backslash$x02$\backslash$x03" , len=3 ->
three bytes generalstring
BIT STRING: VALUE contains the bit string organized by bytes and
LEN is the number of bits.
value="$\backslash$xCF" , len=6 -> bit string="110011" (six bits)
*CHOICE:* if NAME indicates a choice type, VALUE must specify one
of the alternatives with a null terminated string. LEN != 0.
Using "pkix.asn"\:
result=asn1_write_value(cert,
"certificate1.tbsCertificate.subject", "rdnSequence", 1);
*ANY:* VALUE indicates the der encoding of a structure. LEN != 0.
SEQUENCE OF: VALUE must be the null terminated string "NEW" and LEN
!= 0. With this instruction another element is appended in the
sequence. The name of this element will be "?1" if it's the first
one, "?2" for the second and so on.
Using "pkix.asn"\:
result=asn1_write_value(cert,
"certificate1.tbsCertificate.subject.rdnSequence", "NEW", 1);
SET OF: the same as SEQUENCE OF. Using "pkix.asn":
result=asn1_write_value(cert,
"tbsCertificate.subject.rdnSequence.?LAST", "NEW", 1);
*Returns:* 'ASN1_SUCCESS' if the value was set,
'ASN1_ELEMENT_NOT_FOUND' if 'name' is not a valid element, and
'ASN1_VALUE_NOT_VALID' if 'ivalue' has a wrong format.
asn1_read_value
---------------
-- Function: int asn1_read_value (asn1_node ROOT, const char * NAME,
void * IVALUE, int * LEN)
ROOT: pointer to a structure.
NAME: the name of the element inside a structure that you want to
read.
IVALUE: vector that will contain the element's content, must be a
pointer to memory cells already allocated (may be 'NULL' ).
LEN: number of bytes of *value: value[0]..value[len-1]. Initialy
holds the sizeof value.
Returns the value of one element inside a structure. If an element
is OPTIONAL and this returns 'ASN1_ELEMENT_NOT_FOUND' , it means
that this element wasn't present in the der encoding that created
the structure. The first element of a SEQUENCE_OF or SET_OF is
named "?1". The second one "?2" and so on. If the 'root' provided
is a node to specific sequence element, then the keyword "?CURRENT"
is also acceptable and indicates the current sequence element of
this node.
Note that there can be valid values with length zero. In these
case this function will succeed and 'len' will be zero.
*INTEGER:* VALUE will contain a two's complement form integer.
integer=-1 -> value[0]=0xFF , len=1. integer=1 -> value[0]=0x01 ,
len=1.
*ENUMERATED:* As INTEGER (but only with not negative numbers).
*BOOLEAN:* VALUE will be the null terminated string "TRUE" or
"FALSE" and LEN=5 or LEN=6.
OBJECT IDENTIFIER: VALUE will be a null terminated string with each
number separated by a dot (i.e. "1.2.3.543.1").
LEN = strlen(VALUE)+1
*UTCTime:* VALUE will be a null terminated string in one of these
formats: "YYMMDDhhmmss+hh'mm'" or "YYMMDDhhmmss-hh'mm'".
LEN=strlen(VALUE)+1.
*GeneralizedTime:* VALUE will be a null terminated string in the
same format used to set the value.
OCTET STRING: VALUE will contain the octet string and LEN will be
the number of octets.
*GeneralString:* VALUE will contain the generalstring and LEN will
be the number of octets.
BIT STRING: VALUE will contain the bit string organized by bytes
and LEN will be the number of bits.
*CHOICE:* If NAME indicates a choice type, VALUE will specify the
alternative selected.
*ANY:* If NAME indicates an any type, VALUE will indicate the DER
encoding of the structure actually used.
*Returns:* 'ASN1_SUCCESS' if value is returned,
'ASN1_ELEMENT_NOT_FOUND' if 'name' is not a valid element,
'ASN1_VALUE_NOT_FOUND' if there isn't any value for the element
selected, and 'ASN1_MEM_ERROR' if The value vector isn't big enough
to store the result, and in this case 'len' will contain the number
of bytes needed.
asn1_read_value_type
--------------------
-- Function: int asn1_read_value_type (asn1_node ROOT, const char *
NAME, void * IVALUE, int * LEN, unsigned int * ETYPE)
ROOT: pointer to a structure.
NAME: the name of the element inside a structure that you want to
read.
IVALUE: vector that will contain the element's content, must be a
pointer to memory cells already allocated (may be 'NULL' ).
LEN: number of bytes of *value: value[0]..value[len-1]. Initialy
holds the sizeof value.
ETYPE: The type of the value read (ASN1_ETYPE)
Returns the type and value of one element inside a structure. If
an element is OPTIONAL and this returns 'ASN1_ELEMENT_NOT_FOUND' ,
it means that this element wasn't present in the der encoding that
created the structure. The first element of a SEQUENCE_OF or
SET_OF is named "?1". The second one "?2" and so on. If the
'root' provided is a node to specific sequence element, then the
keyword "?CURRENT" is also acceptable and indicates the current
sequence element of this node.
Note that there can be valid values with length zero. In these
case this function will succeed and 'len' will be zero.
*INTEGER:* VALUE will contain a two's complement form integer.
integer=-1 -> value[0]=0xFF , len=1. integer=1 -> value[0]=0x01 ,
len=1.
*ENUMERATED:* As INTEGER (but only with not negative numbers).
*BOOLEAN:* VALUE will be the null terminated string "TRUE" or
"FALSE" and LEN=5 or LEN=6.
OBJECT IDENTIFIER: VALUE will be a null terminated string with each
number separated by a dot (i.e. "1.2.3.543.1").
LEN = strlen(VALUE)+1
*UTCTime:* VALUE will be a null terminated string in one of these
formats: "YYMMDDhhmmss+hh'mm'" or "YYMMDDhhmmss-hh'mm'".
LEN=strlen(VALUE)+1.
*GeneralizedTime:* VALUE will be a null terminated string in the
same format used to set the value.
OCTET STRING: VALUE will contain the octet string and LEN will be
the number of octets.
*GeneralString:* VALUE will contain the generalstring and LEN will
be the number of octets.
BIT STRING: VALUE will contain the bit string organized by bytes
and LEN will be the number of bits.
*CHOICE:* If NAME indicates a choice type, VALUE will specify the
alternative selected.
*ANY:* If NAME indicates an any type, VALUE will indicate the DER
encoding of the structure actually used.
*Returns:* 'ASN1_SUCCESS' if value is returned,
'ASN1_ELEMENT_NOT_FOUND' if 'name' is not a valid element,
'ASN1_VALUE_NOT_FOUND' if there isn't any value for the element
selected, and 'ASN1_MEM_ERROR' if The value vector isn't big enough
to store the result, and in this case 'len' will contain the number
of bytes needed.
asn1_read_tag
-------------
-- Function: int asn1_read_tag (asn1_node ROOT, const char * NAME, int
* TAGVALUE, int * CLASSVALUE)
ROOT: pointer to a structure
NAME: the name of the element inside a structure.
TAGVALUE: variable that will contain the TAG value.
CLASSVALUE: variable that will specify the TAG type.
Returns the TAG and the CLASS of one element inside a structure.
CLASS can have one of these constants: 'ASN1_CLASS_APPLICATION' ,
'ASN1_CLASS_UNIVERSAL' , 'ASN1_CLASS_PRIVATE' or
'ASN1_CLASS_CONTEXT_SPECIFIC' .
*Returns:* 'ASN1_SUCCESS' if successful, 'ASN1_ELEMENT_NOT_FOUND'
if 'name' is not a valid element.
asn1_read_node_value
--------------------
-- Function: int asn1_read_node_value (asn1_node NODE,
asn1_data_node_st * DATA)
NODE: pointer to a node.
DATA: a point to a asn1_data_node_st
Returns the value a data node inside a asn1_node structure. The
data returned should be handled as constant values.
*Returns:* 'ASN1_SUCCESS' if the node exists.
File: libtasn1.info, Node: DER functions, Next: Error handling functions, Prev: ASN.1 field functions, Up: Function reference
4.3 DER functions
=================
asn1_length_der
---------------
-- Function: void asn1_length_der (unsigned long int LEN, unsigned char
* DER, int * DER_LEN)
LEN: value to convert.
DER: buffer to hold the returned encoding (may be 'NULL' ).
DER_LEN: number of meaningful bytes of ANS
(der[0]..der[der_len-1]).
Creates the DER encoding of the provided length value. The 'der'
buffer must have enough room for the output. The maximum length
this function will encode is 'ASN1_MAX_LENGTH_SIZE' .
To know the size of the DER encoding use a 'NULL' value for 'der' .
asn1_octet_der
--------------
-- Function: void asn1_octet_der (const unsigned char * STR, int
STR_LEN, unsigned char * DER, int * DER_LEN)
STR: the input data.
STR_LEN: STR length (str[0]..str[*str_len-1]).
DER: encoded string returned.
DER_LEN: number of meaningful bytes of DER
(der[0]..der[der_len-1]).
Creates a length-value DER encoding for the input data. The DER
encoding of the input data will be placed in the 'der' variable.
Note that the OCTET STRING tag is not included in the output.
This function does not return any value because it is expected that
'der_len' will contain enough bytes to store the string plus the
DER encoding. The DER encoding size can be obtained using
'asn1_length_der()' .
asn1_encode_simple_der
----------------------
-- Function: int asn1_encode_simple_der (unsigned int ETYPE, const
unsigned char * STR, unsigned int STR_LEN, unsigned char * TL,
unsigned int * TL_LEN)
ETYPE: The type of the string to be encoded (ASN1_ETYPE_)
STR: the string data.
STR_LEN: the string length
TL: the encoded tag and length
TL_LEN: the bytes of the 'tl' field
Creates the DER encoding for various simple ASN.1 types like
strings etc. It stores the tag and length in 'tl' , which should
have space for at least 'ASN1_MAX_TL_SIZE' bytes. Initially
'tl_len' should contain the size of 'tl' .
The complete DER encoding should consist of the value in 'tl'
appended with the provided 'str' .
*Returns:* 'ASN1_SUCCESS' if successful or an error value.
asn1_bit_der
------------
-- Function: void asn1_bit_der (const unsigned char * STR, int BIT_LEN,
unsigned char * DER, int * DER_LEN)
STR: BIT string.
BIT_LEN: number of meaningful bits in STR.
DER: string returned.
DER_LEN: number of meaningful bytes of DER
(der[0]..der[ans_len-1]).
Creates a length-value DER encoding for the input data as it would
have been for a BIT STRING. The DER encoded data will be copied in
'der' .
Note that the BIT STRING tag is not included in the output.
This function does not return any value because it is expected that
'der_len' will contain enough bytes to store the string plus the
DER encoding. The DER encoding size can be obtained using
'asn1_length_der()' .
asn1_der_coding
---------------
-- Function: int asn1_der_coding (asn1_node ELEMENT, const char * NAME,
void * IDER, int * LEN, char * ERRORDESCRIPTION)
ELEMENT: pointer to an ASN1 element
NAME: the name of the structure you want to encode (it must be
inside *POINTER).
IDER: vector that will contain the DER encoding. DER must be a
pointer to memory cells already allocated.
LEN: number of bytes of * 'ider' : 'ider' [0].. 'ider' [len-1],
Initialy holds the sizeof of der vector.
ERRORDESCRIPTION: return the error description or an empty string
if success.
Creates the DER encoding for the NAME structure (inside *POINTER
structure).
*Returns:* 'ASN1_SUCCESS' if DER encoding OK,
'ASN1_ELEMENT_NOT_FOUND' if 'name' is not a valid element,
'ASN1_VALUE_NOT_FOUND' if there is an element without a value,
'ASN1_MEM_ERROR' if the 'ider' vector isn't big enough and in this
case 'len' will contain the length needed.
asn1_get_length_der
-------------------
-- Function: long asn1_get_length_der (const unsigned char * DER, int
DER_LEN, int * LEN)
DER: DER data to decode.
DER_LEN: Length of DER data to decode.
LEN: Output variable containing the length of the DER length field.
Extract a length field from DER data.
*Returns:* Return the decoded length value, or -1 on indefinite
length, or -2 when the value was too big to fit in a int, or -4
when the decoded length value plus 'len' would exceed 'der_len' .
asn1_get_tag_der
----------------
-- Function: int asn1_get_tag_der (const unsigned char * DER, int
DER_LEN, unsigned char * CLS, int * LEN, unsigned long * TAG)
DER: DER data to decode.
DER_LEN: Length of DER data to decode.
CLS: Output variable containing decoded class.
LEN: Output variable containing the length of the DER TAG data.
TAG: Output variable containing the decoded tag.
Decode the class and TAG from DER code.
*Returns:* Returns 'ASN1_SUCCESS' on success, or an error.
asn1_get_length_ber
-------------------
-- Function: long asn1_get_length_ber (const unsigned char * BER, int
BER_LEN, int * LEN)
BER: BER data to decode.
BER_LEN: Length of BER data to decode.
LEN: Output variable containing the length of the BER length field.
Extract a length field from BER data. The difference to
'asn1_get_length_der()' is that this function will return a length
even if the value has indefinite encoding.
*Returns:* Return the decoded length value, or negative value when
the value was too big.
*Since:* 2.0
asn1_get_octet_der
------------------
-- Function: int asn1_get_octet_der (const unsigned char * DER, int
DER_LEN, int * RET_LEN, unsigned char * STR, int STR_SIZE, int
* STR_LEN)
DER: DER data to decode containing the OCTET SEQUENCE.
DER_LEN: The length of the 'der' data to decode.
RET_LEN: Output variable containing the encoded length of the DER
data.
STR: Pre-allocated output buffer to put decoded OCTET SEQUENCE in.
STR_SIZE: Length of pre-allocated output buffer.
STR_LEN: Output variable containing the length of the contents of
the OCTET SEQUENCE.
Extract an OCTET SEQUENCE from DER data. Note that this function
expects the DER data past the tag field, i.e., the length and
content octets.
*Returns:* Returns 'ASN1_SUCCESS' on success, or an error.
asn1_get_object_id_der
----------------------
-- Function: int asn1_get_object_id_der (const unsigned char * DER, int
DER_LEN, int * RET_LEN, char * STR, int STR_SIZE)
DER: DER data to decode containing the OBJECT IDENTIFIER
DER_LEN: Length of DER data to decode.
RET_LEN: Output variable containing the length of the DER data.
STR: Pre-allocated output buffer to put the textual object id in.
STR_SIZE: Length of pre-allocated output buffer.
Converts a DER encoded object identifier to its textual form.
*Returns:* 'ASN1_SUCCESS' on success, or an error.
asn1_get_bit_der
----------------
-- Function: int asn1_get_bit_der (const unsigned char * DER, int
DER_LEN, int * RET_LEN, unsigned char * STR, int STR_SIZE, int
* BIT_LEN)
DER: DER data to decode containing the BIT SEQUENCE.
DER_LEN: Length of DER data to decode.
RET_LEN: Output variable containing the length of the DER data.
STR: Pre-allocated output buffer to put decoded BIT SEQUENCE in.
STR_SIZE: Length of pre-allocated output buffer.
BIT_LEN: Output variable containing the size of the BIT SEQUENCE.
Extract a BIT SEQUENCE from DER data.
*Returns:* 'ASN1_SUCCESS' on success, or an error.
asn1_der_decoding2
------------------
-- Function: int asn1_der_decoding2 (asn1_node * ELEMENT, const void *
IDER, int * MAX_IDER_LEN, unsigned int FLAGS, char *
ERRORDESCRIPTION)
ELEMENT: pointer to an ASN1 structure.
IDER: vector that contains the DER encoding.
MAX_IDER_LEN: pointer to an integer giving the information about
the maximal number of bytes occupied by * 'ider' . The real size
of the DER encoding is returned through this pointer.
FLAGS: flags controlling the behaviour of the function.
ERRORDESCRIPTION: null-terminated string contains details when an
error occurred.
Fill the structure * 'element' with values of a DER encoding
string. The structure must just be created with function
'asn1_create_element()' .
If 'ASN1_DECODE_FLAG_ALLOW_PADDING' flag is set then the function
will ignore padding after the decoded DER data. Upon a successful
return the value of * 'max_ider_len' will be set to the number of
bytes decoded.
If 'ASN1_DECODE_FLAG_STRICT_DER' flag is set then the function will
not decode any BER-encoded elements.
*Returns:* 'ASN1_SUCCESS' if DER encoding OK,
'ASN1_ELEMENT_NOT_FOUND' if 'ELEMENT' is 'NULL' , and
'ASN1_TAG_ERROR' or 'ASN1_DER_ERROR' if the der encoding doesn't
match the structure name (* 'ELEMENT' deleted).
asn1_der_decoding
-----------------
-- Function: int asn1_der_decoding (asn1_node * ELEMENT, const void *
IDER, int IDER_LEN, char * ERRORDESCRIPTION)
ELEMENT: pointer to an ASN1 structure.
IDER: vector that contains the DER encoding.
IDER_LEN: number of bytes of * 'ider' : 'ider' [0].. 'ider'
[len-1].
ERRORDESCRIPTION: null-terminated string contains details when an
error occurred.
Fill the structure * 'element' with values of a DER encoding
string. The structure must just be created with function
'asn1_create_element()' .
Note that the * 'element' variable is provided as a pointer for
historical reasons.
*Returns:* 'ASN1_SUCCESS' if DER encoding OK,
'ASN1_ELEMENT_NOT_FOUND' if 'ELEMENT' is 'NULL' , and
'ASN1_TAG_ERROR' or 'ASN1_DER_ERROR' if the der encoding doesn't
match the structure name (* 'ELEMENT' deleted).
asn1_der_decoding_element
-------------------------
-- Function: int asn1_der_decoding_element (asn1_node * STRUCTURE,
const char * ELEMENTNAME, const void * IDER, int LEN, char *
ERRORDESCRIPTION)
STRUCTURE: pointer to an ASN1 structure
ELEMENTNAME: name of the element to fill
IDER: vector that contains the DER encoding of the whole structure.
LEN: number of bytes of *der: der[0]..der[len-1]
ERRORDESCRIPTION: null-terminated string contains details when an
error occurred.
Fill the element named 'ELEMENTNAME' with values of a DER encoding
string. The structure must just be created with function
'asn1_create_element()' . The DER vector must contain the encoding
string of the whole 'STRUCTURE' . If an error occurs during the
decoding procedure, the * 'STRUCTURE' is deleted and set equal to
'NULL' .
This function is deprecated and may just be an alias to
asn1_der_decoding in future versions. Use 'asn1_der_decoding()'
instead.
*Returns:* 'ASN1_SUCCESS' if DER encoding OK,
'ASN1_ELEMENT_NOT_FOUND' if ELEMENT is 'NULL' or 'elementName' ==
NULL, and 'ASN1_TAG_ERROR' or 'ASN1_DER_ERROR' if the der encoding
doesn't match the structure 'structure' (*ELEMENT deleted).
asn1_der_decoding_startEnd
--------------------------
-- Function: int asn1_der_decoding_startEnd (asn1_node ELEMENT, const
void * IDER, int IDER_LEN, const char * NAME_ELEMENT, int *
START, int * END)
ELEMENT: pointer to an ASN1 element
IDER: vector that contains the DER encoding.
IDER_LEN: number of bytes of * 'ider' : 'ider' [0].. 'ider'
[len-1]
NAME_ELEMENT: an element of NAME structure.
START: the position of the first byte of NAME_ELEMENT decoding (
'ider' [*start])
END: the position of the last byte of NAME_ELEMENT decoding (
'ider' [*end])
Find the start and end point of an element in a DER encoding
string. I mean that if you have a der encoding and you have
already used the function 'asn1_der_decoding()' to fill a
structure, it may happen that you want to find the piece of string
concerning an element of the structure.
One example is the sequence "tbsCertificate" inside an X509
certificate.
Note that since libtasn1 3.7 the 'ider' and 'ider_len' parameters
can be omitted, if the element is already decoded using
'asn1_der_decoding()' .
*Returns:* 'ASN1_SUCCESS' if DER encoding OK,
'ASN1_ELEMENT_NOT_FOUND' if ELEMENT is 'asn1_node' EMPTY or
'name_element' is not a valid element, 'ASN1_TAG_ERROR' or
'ASN1_DER_ERROR' if the der encoding doesn't match the structure
ELEMENT.
asn1_expand_any_defined_by
--------------------------
-- Function: int asn1_expand_any_defined_by (asn1_node DEFINITIONS,
asn1_node * ELEMENT)
DEFINITIONS: ASN1 definitions
ELEMENT: pointer to an ASN1 structure
Expands every "ANY DEFINED BY" element of a structure created from
a DER decoding process (asn1_der_decoding function). The element
ANY must be defined by an OBJECT IDENTIFIER. The type used to
expand the element ANY is the first one following the definition of
the actual value of the OBJECT IDENTIFIER.
*Returns:* 'ASN1_SUCCESS' if Substitution OK, 'ASN1_ERROR_TYPE_ANY'
if some "ANY DEFINED BY" element couldn't be expanded due to a
problem in OBJECT_ID -> TYPE association, or other error codes
depending on DER decoding.
asn1_expand_octet_string
------------------------
-- Function: int asn1_expand_octet_string (asn1_node DEFINITIONS,
asn1_node * ELEMENT, const char * OCTETNAME, const char *
OBJECTNAME)
DEFINITIONS: ASN1 definitions
ELEMENT: pointer to an ASN1 structure
OCTETNAME: name of the OCTECT STRING field to expand.
OBJECTNAME: name of the OBJECT IDENTIFIER field to use to define
the type for expansion.
Expands an "OCTET STRING" element of a structure created from a DER
decoding process (the 'asn1_der_decoding()' function). The type
used for expansion is the first one following the definition of the
actual value of the OBJECT IDENTIFIER indicated by OBJECTNAME.
*Returns:* 'ASN1_SUCCESS' if substitution OK,
'ASN1_ELEMENT_NOT_FOUND' if 'objectName' or 'octetName' are not
correct, 'ASN1_VALUE_NOT_VALID' if it wasn't possible to find the
type to use for expansion, or other errors depending on DER
decoding.
asn1_decode_simple_der
----------------------
-- Function: int asn1_decode_simple_der (unsigned int ETYPE, const
unsigned char * DER, unsigned int _DER_LEN, const unsigned
char ** STR, unsigned int * STR_LEN)
ETYPE: The type of the string to be encoded (ASN1_ETYPE_)
DER: the encoded string
_DER_LEN: the bytes of the encoded string
STR: a pointer to the data
STR_LEN: the length of the data
Decodes a simple DER encoded type (e.g. a string, which is not
constructed). The output is a pointer inside the 'der' .
*Returns:* 'ASN1_SUCCESS' if successful or an error value.
asn1_decode_simple_ber
----------------------
-- Function: int asn1_decode_simple_ber (unsigned int ETYPE, const
unsigned char * DER, unsigned int _DER_LEN, unsigned char **
STR, unsigned int * STR_LEN, unsigned int * BER_LEN)
ETYPE: The type of the string to be encoded (ASN1_ETYPE_)
DER: the encoded string
_DER_LEN: the bytes of the encoded string
STR: a pointer to the data
STR_LEN: the length of the data
BER_LEN: the total length occupied by BER (may be 'NULL' )
Decodes a BER encoded type. The output is an allocated value of
the data. This decodes BER STRINGS only. Other types are decoded
as DER.
*Returns:* 'ASN1_SUCCESS' if successful or an error value.
File: libtasn1.info, Node: Error handling functions, Next: Auxilliary functions, Prev: DER functions, Up: Function reference
4.4 Error handling functions
============================
asn1_perror
-----------
-- Function: void asn1_perror (int ERROR)
ERROR: is an error returned by a libtasn1 function.
Prints a string to stderr with a description of an error. This
function is like 'perror()' . The only difference is that it
accepts an error returned by a libtasn1 function.
*Since:* 1.6
asn1_strerror
-------------
-- Function: const char * asn1_strerror (int ERROR)
ERROR: is an error returned by a libtasn1 function.
Returns a string with a description of an error. This function is
similar to strerror. The only difference is that it accepts an
error (number) returned by a libtasn1 function.
*Returns:* Pointer to static zero-terminated string describing
error code.
*Since:* 1.6
File: libtasn1.info, Node: Auxilliary functions, Prev: Error handling functions, Up: Function reference
4.5 Auxilliary functions
========================
asn1_find_node
--------------
-- Function: asn1_node asn1_find_node (asn1_node POINTER, const char *
NAME)
POINTER: NODE_ASN element pointer.
NAME: null terminated string with the element's name to find.
Searches for an element called 'name' starting from 'pointer' .
The name is composed by differents identifiers separated by dots.
When * 'pointer' has a name, the first identifier must be the name
of * 'pointer' , otherwise it must be the name of one child of *
'pointer' .
*Returns:* the search result, or 'NULL' if not found.
asn1_check_version
------------------
-- Function: const char * asn1_check_version (const char * REQ_VERSION)
REQ_VERSION: Required version number, or 'NULL' .
Check that the version of the library is at minimum the requested
one and return the version string; return 'NULL' if the condition
is not satisfied. If a 'NULL' is passed to this function, no check
is done, but the version string is simply returned.
See 'ASN1_VERSION' for a suitable 'req_version' string.
*Returns:* Version string of run-time library, or 'NULL' if the
run-time library does not meet the required version number.
File: libtasn1.info, Node: Copying Information, Next: Concept Index, Prev: Function reference, Up: Top
Appendix A Copying Information
******************************
* Menu:
* GNU Free Documentation License:: License for copying this manual.
File: libtasn1.info, Node: GNU Free Documentation License, Up: Copying Information
A.1 GNU Free Documentation License
==================================
Version 1.3, 3 November 2008
Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<http://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
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ADDENDUM: How to use this License for your documents
====================================================
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File: libtasn1.info, Node: Concept Index, Next: Function and Data Index, Prev: Copying Information, Up: Top
Concept Index
*************
[index]
* Menu:
* ASN.1 schema: ASN.1 syntax. (line 6)
* asn1Coding program: Invoking asn1Coding. (line 6)
* asn1Decoding program: Invoking asn1Decoding.
(line 6)
* asn1Parser program: Invoking asn1Parser. (line 6)
* FDL, GNU Free Documentation License: GNU Free Documentation License.
(line 6)
* Future developments: Future developments. (line 6)
* Header file libtasn1.h: Library Notes. (line 6)
* Main type asn1_node: Library Notes. (line 8)
* Porting: Introduction. (line 32)
* Supported ASN.1 types, list of: ASN.1 syntax. (line 38)
* threads: Introduction. (line 29)
File: libtasn1.info, Node: Function and Data Index, Prev: Concept Index, Up: Top
Function and Data Index
***********************
[index]
* Menu:
* asn1_array2tree: ASN.1 field functions.
(line 9)
* asn1_bit_der: DER functions. (line 77)
* asn1_check_version: Auxilliary functions.
(line 26)
* asn1_copy_node: ASN.1 field functions.
(line 144)
* asn1_create_element: ASN.1 field functions.
(line 72)
* asn1_decode_simple_ber: DER functions. (line 456)
* asn1_decode_simple_der: DER functions. (line 435)
* asn1_delete_element: ASN.1 field functions.
(line 57)
* asn1_delete_structure: ASN.1 field functions.
(line 30)
* asn1_delete_structure2: ASN.1 field functions.
(line 42)
* asn1_der_coding: DER functions. (line 102)
* asn1_der_decoding: DER functions. (line 289)
* asn1_der_decoding2: DER functions. (line 253)
* asn1_der_decoding_element: DER functions. (line 316)
* asn1_der_decoding_startEnd: DER functions. (line 349)
* asn1_dup_node: ASN.1 field functions.
(line 162)
* asn1_encode_simple_der: DER functions. (line 51)
* asn1_expand_any_defined_by: DER functions. (line 389)
* asn1_expand_octet_string: DER functions. (line 409)
* asn1_find_node: Auxilliary functions.
(line 9)
* asn1_find_structure_from_oid: ASN.1 field functions.
(line 129)
* asn1_get_bit_der: DER functions. (line 231)
* asn1_get_length_ber: DER functions. (line 166)
* asn1_get_length_der: DER functions. (line 130)
* asn1_get_object_id_der: DER functions. (line 212)
* asn1_get_octet_der: DER functions. (line 186)
* asn1_get_tag_der: DER functions. (line 147)
* asn1_length_der: DER functions. (line 9)
* asn1_number_of_elements: ASN.1 field functions.
(line 111)
* asn1_octet_der: DER functions. (line 27)
* asn1_parser2array: ASN.1 schema functions.
(line 35)
* asn1_parser2tree: ASN.1 schema functions.
(line 9)
* asn1_perror: Error handling functions.
(line 9)
* asn1_print_structure: ASN.1 field functions.
(line 93)
* asn1_read_node_value: ASN.1 field functions.
(line 453)
* asn1_read_tag: ASN.1 field functions.
(line 432)
* asn1_read_value: ASN.1 field functions.
(line 286)
* asn1_read_value_type: ASN.1 field functions.
(line 358)
* asn1_strerror: Error handling functions.
(line 21)
* asn1_write_value: ASN.1 field functions.
(line 176)
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