This manual is for Libtasn1 (version 1.6, 4 November 2008), which is a library for Abstract Syntax Notation One (ASN.1) and Distinguish Encoding Rules (DER) manipulation.
Copyright © 2004, 2006, 2007, 2008 Free Software Foundation Copyright © 2001, 2002, 2003 Fabio Fiorina
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”.
Indices
This document describes the Libtasn1 library developed for ASN.1 (Abstract Syntax Notation One) structures management and DER (Distinguished Encoding Rules) encoding functions.
The main features of this library are:
The parser is case sensitive. The comments begin with "– " and end at the end of lines. An example is in "pkix.asn" file. ASN.1 definitions must have this syntax:
definitions_name {<object definition>}
DEFINITIONS <EXPLICIT or IMPLICIT> TAGS ::=
BEGIN
<type and constants definitions>
END
The token "::=" must be separate from others elements, so this is a wrong declaration:
;; INCORRECT
Version ::=INTEGER
the correct form is:
Version ::= INTEGER
Here is the list of types that the parser can manage:
This version doesn't manage REAL type. It doesn't allow the "EXPORT" and "IMPORT" sections too.
The SIZE constraints are allowed, but no check is done on them.
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
To identify the type 'Group' you have to use the null terminated string "Example.Group". These strings are used in functions that are described below.
Others examples:
Field 'id' in 'Group' type : "Example.Group.id".
Field 'value1' in field 'value' in type 'Group': "Example.Group.value.value1".
Elements of structured types that don't have a name, receive the name "?1","?2", and so on.
The name "?LAST" indicates the last element of a SET_OF or
SEQUENCE_OF.
The header file of this library is libtasn1.h.
The main type used in it is ASN1_TYPE, and it's used to store
the ASN.1 definitions and structures (instances).
The constant ASN1_TYPE_EMPTY can be used for the variable initialization. For example:
ASN1_TYPE definitions=ASN1_TYPE_EMPTY;
Some functions require a parameter named errorDescription of char*
type. The array must be already allocated and must have at least
ASN1_MAX_ERROR_DESCRIPTION_SIZE bytes (E.g, as in char
Description[ASN1_MAX_ERROR_DESCRIPTION_SIZE];).
ASN1_MAX_NAME_SIZE indicates the maximum number of characters of a
name inside a file with ASN1 definitions.
asn1Parser reads one file with ASN1 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.
asn1Coding generates a DER encoding from a file with ASN1 definitions and another one with assignments.
The file with assignments must have this syntax:
InstanceName Asn1Definition nameString value nameString value ...
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.
asn1Decoding generates an ASN1 structure from a file with ASN1 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. -c : checks the syntax only. -o file : output file.
file_name: specify the path and the name of file that contains ASN.1 declarations.
definitions: return the pointer to the structure created from "file_name" ASN.1 declarations.
errorDescription: return the error description or an empty string if success.
Creates the structures needed to manage the definitions included in *FILE_NAME file.
Returns: ASN1_SUCCESS: The file has a correct syntax and every identifier is known.
ASN1_ELEMENT_NOT_EMPTY: *POINTER not ASN1_TYPE_EMPTY.
ASN1_FILE_NOT_FOUND: An error occured while opening FILE_NAME.
ASN1_SYNTAX_ERROR: The syntax is not correct.
ASN1_IDENTIFIER_NOT_FOUND: In the file there is an identifier that is not defined.
ASN1_NAME_TOO_LONG: In the file there is an identifier whith more than ASN1_MAX_NAME_SIZE characters.
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.
errorDescription: return the error description or an empty string if success.
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: The file has a correct syntax and every identifier is known.
ASN1_FILE_NOT_FOUND: An error occured while opening FILE_NAME.
ASN1_SYNTAX_ERROR: The syntax is not correct.
ASN1_IDENTIFIER_NOT_FOUND: In the file there is an identifier that is not defined.
ASN1_NAME_TOO_LONG: In the file there is an identifier whith more than ASN1_MAX_NAME_SIZE characters.
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.
arrayis a vector created byasn1_parser2array().Returns: ASN1_SUCCESS: Structure created correctly.
ASN1_ELEMENT_NOT_EMPTY: *
definitionsnot ASN1_TYPE_EMPTY.ASN1_IDENTIFIER_NOT_FOUND: In the file there is an identifier that is not defined (see
errorDescriptionfor more information).ASN1_ARRAY_ERROR: The array pointed by
arrayis wrong.
structure: pointer to the structure that you want to delete.
Deletes the structure *
structure. At the end, *structureis set to ASN1_TYPE_EMPTY.Returns: ASN1_SUCCESS: Everything OK.
ASN1_ELEMENT_NOT_FOUND: *
structurewas ASN1_TYPE_EMPTY.
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_nameinside *structure.Returns: ASN1_SUCCESS: Everything OK.
ASN1_ELEMENT_NOT_FOUND: The name element was not found.
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_structure(cert_def, "PKIX1.Certificate", certptr);
Returns: ASN1_SUCCESS: Creation OK.
ASN1_ELEMENT_NOT_FOUND: SOURCE_NAME isn't known
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, orASN1_PRINT_ALL.Prints on the
outfile descriptor the structure's tree starting from thenameelement inside the structurestructure.
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: Creation OK.
ASN1_ELEMENT_NOT_FOUND: NAME isn't known.
ASN1_GENERIC_ERROR: Pointer num equal to NULL.
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.
dst: Destination ASN1_TYPE node.
dst_name: Field name in destination node.
src: Source ASN1_TYPE node.
src_name: Field name in source node.
Create a deep copy of a ASN1_TYPE variable.
Return value: Return ASN1_SUCCESS on success.
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: Set value OK.
ASN1_ELEMENT_NOT_FOUND: NAME is not a valid element.
ASN1_VALUE_NOT_VALID: VALUE has a wrong format.
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.
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 the function "read_value" 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.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: Set value OK.
ASN1_ELEMENT_NOT_FOUND: NAME is not a valid element.
ASN1_VALUE_NOT_FOUND: There isn't any value for the element selected.
ASN1_MEM_ERROR: The value vector isn't big enough to store the result. In this case LEN will contain the number of bytes needed.
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_PRIVATEorASN1_CLASS_CONTEXT_SPECIFIC.Returns: ASN1_SUCCESS: Set value OK.
ASN1_ELEMENT_NOT_FOUND: NAME is not a valid element.
len: value to convert.
ans: string returned.
ans_len: number of meaningful bytes of ANS (ans[0]..ans[ans_len-1]).
Creates the DER coding for the LEN parameter (only the length). The
ansbuffer is pre-allocated and must have room for the output.
str: OCTET string.
str_len: STR length (str[0]..str[str_len-1]).
der: string returned.
der_len: number of meaningful bytes of DER (der[0]..der[ans_len-1]).
Creates the DER coding for an OCTET type (length included).
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 the DER coding for a BIT STRING type (length and pad included).
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.Creates the DER encoding for the NAME structure (inside *POINTER structure).
Returns: ASN1_SUCCESS: DER encoding OK.
ASN1_ELEMENT_NOT_FOUND: NAME is not a valid element.
ASN1_VALUE_NOT_FOUND: There is an element without a value.
ASN1_MEM_ERROR:
idervector isn't big enough. Also in this case LEN will contain the length needed.
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.
Return value: Return the decoded length value, or -1 on indefinite length, or -2 when the value was too big.
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.
Return value: Returns ASN1_SUCCESS on success, or an error.
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.Return value: Return the decoded length value, or negative value when the value was too big.
Since: 2.0
der: DER data to decode containing the OCTET 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 OCTET SEQUENCE in.
str_size: Length of pre-allocated output buffer.
str_len: Output variable containing the length of the OCTET SEQUENCE.
Extract an OCTET SEQUENCE from DER data.
Return value: Returns ASN1_SUCCESS on success, or an error.
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.
Return value: Return ASN1_SUCCESS on success, or an error.
element: pointer to an ASN1 structure.
ider: vector that contains the DER encoding.
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 sructure must just be created with function 'create_stucture'. If an error occurs during the decoding procedure, the *ELEMENT is deleted and set equal to
ASN1_TYPE_EMPTY.Returns: ASN1_SUCCESS: DER encoding OK.
ASN1_ELEMENT_NOT_FOUND: ELEMENT is ASN1_TYPE_EMPTY.
ASN1_TAG_ERROR,ASN1_DER_ERROR: The der encoding doesn't match the structure NAME. *ELEMENT deleted.
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 sructure must just be created with function 'create_stucture'. 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
ASN1_TYPE_EMPTY.Returns: ASN1_SUCCESS: DER encoding OK.
ASN1_ELEMENT_NOT_FOUND: ELEMENT is ASN1_TYPE_EMPTY or elementName == NULL.
ASN1_TAG_ERROR,ASN1_DER_ERROR: The der encoding doesn't match the structure STRUCTURE. *ELEMENT deleted.
element: pointer to an ASN1 element
ider: vector that contains the DER encoding.
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.
Example: the sequence "tbsCertificate" inside an X509 certificate.
Returns: ASN1_SUCCESS: DER encoding OK.
ASN1_ELEMENT_NOT_FOUND: ELEMENT is ASN1_TYPE EMPTY or NAME_ELEMENT is not a valid element.
ASN1_TAG_ERROR,ASN1_DER_ERROR: the der encoding doesn't match the structure 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: Substitution OK.
ASN1_ERROR_TYPE_ANY: Some "ANY DEFINED BY" element couldn't be expanded due to a problem in OBJECT_ID -> TYPE association.
other errors: Result of der decoding process.
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 (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: Substitution OK.
ASN1_ELEMENT_NOT_FOUND: OBJECTNAME or OCTETNAME are not correct.
ASN1_VALUE_NOT_VALID: Wasn't possible to find the type to use for expansion.
other errors: result of der decoding process.
error: is an error returned by a libtasn1 function.
This function is like
perror(). The only difference is that it accepts an error returned by a libtasn1 function.Since: 1.6
error: is an error returned by a libtasn1 function.
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
error: is an error returned by a libtasn1 function.
This function is like
perror(). The only difference is that it accepts an error returned by a libtasn1 function.Deprecated: Use
asn1_perror()instead.
error: is an error returned by a libtasn1 function.
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.
Deprecated: Use
asn1_strerror()instead.
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.
Return value: the searching result. NULL if not found.
req_version: Required version number, or NULL.
Check that the the version of the library is at minimum the requested one and return the version string; return
NULLif the condition is not satisfied. If aNULLis passed to this function, no check is done, but the version string is simply returned.See
ASN1_VERSIONfor a suitablereq_versionstring.Return value: Version string of run-time library, or
NULLif the run-time library does not meet the required version number.
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You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions:
A compilation of a covered work with other separate and independent works, which are not by their nature extensions of the covered work, and which are not combined with it such as to form a larger program, in or on a volume of a storage or distribution medium, is called an “aggregate” if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation's users beyond what the individual works permit. Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate.
You may convey a covered work in object code form under the terms of sections 4 and 5, provided that you also convey the machine-readable Corresponding Source under the terms of this License, in one of these ways:
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“Additional permissions” are terms that supplement the terms of this License by making exceptions from one or more of its conditions. Additional permissions that are applicable to the entire Program shall be treated as though they were included in this License, to the extent that they are valid under applicable law. If additional permissions apply only to part of the Program, that part may be used separately under those permissions, but the entire Program remains governed by this License without regard to the additional permissions.
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Notwithstanding any other provision of this License, for material you add to a covered work, you may (if authorized by the copyright holders of that material) supplement the terms of this License with terms:
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Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law.
If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.
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The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.
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THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.
If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
one line to give the program's name and a brief idea of what it does.
Copyright (C) year name of author
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see http://www.gnu.org/licenses/.
Also add information on how to contact you by electronic and paper mail.
If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
program Copyright (C) year name of author
This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’.
This is free software, and you are welcome to redistribute it
under certain conditions; type ‘show c’ for details.
The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an “about box”.
You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see http://www.gnu.org/licenses/.
The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read http://www.gnu.org/philosophy/why-not-lgpl.html.
asn1_array2tree: ASN.1 field functionsasn1_bit_der: DER functionsasn1_check_version: Auxilliary functionsasn1_copy_node: ASN.1 field functionsasn1_create_element: ASN.1 field functionsasn1_delete_element: ASN.1 field functionsasn1_delete_structure: ASN.1 field functionsasn1_der_coding: DER functionsasn1_der_decoding: DER functionsasn1_der_decoding_element: DER functionsasn1_der_decoding_startEnd: DER functionsasn1_expand_any_defined_by: DER functionsasn1_expand_octet_string: DER functionsasn1_find_node: Auxilliary functionsasn1_find_structure_from_oid: ASN.1 field functionsasn1_get_bit_der: DER functionsasn1_get_length_ber: DER functionsasn1_get_length_der: DER functionsasn1_get_octet_der: DER functionsasn1_get_tag_der: DER functionsasn1_length_der: DER functionsasn1_number_of_elements: ASN.1 field functionsasn1_octet_der: DER functionsasn1_parser2array: ASN.1 schema functionsasn1_parser2tree: ASN.1 schema functionsasn1_perror: Error handling functionsasn1_print_structure: ASN.1 field functionsasn1_read_tag: ASN.1 field functionsasn1_read_value: ASN.1 field functionsasn1_strerror: Error handling functionsasn1_write_value: ASN.1 field functionslibtasn1_perror: Error handling functionslibtasn1_strerror: Error handling functions