ASN.1 (Abstract Syntax Notation One) DER (Distinguished Encoding Rules) is a standard-backed serialization scheme used in many different use-cases. Particularly popular usage scenarios are X.509 certificates and some telecommunication / networking protocols.
DER is self-describing encoding scheme which allows representation of simple, atomic data elements, such as strings and numbers, and complex objects, such as sequences of other elements.
DER is a subset of BER (Basic Encoding Rules), with an emphasis on being non-ambiguous: there's always exactly one canonical way to encode a data structure defined in terms of ASN.1 using DER.
This spec allows full parsing of format syntax, but to understand the semantics, one would typically require a dictionary of Object Identifiers (OIDs), to match OID bodies against some human-readable list of constants. OIDs are covered by many different standards, so typically it's simpler to use a pre-compiled list of them, such as:
This page hosts a formal specification of ASN.1 DER (Abstract Syntax Notation One, Distinguished Encoding Rules) using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
<?php
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
/**
* ASN.1 (Abstract Syntax Notation One) DER (Distinguished Encoding
* Rules) is a standard-backed serialization scheme used in many
* different use-cases. Particularly popular usage scenarios are X.509
* certificates and some telecommunication / networking protocols.
*
* DER is self-describing encoding scheme which allows representation
* of simple, atomic data elements, such as strings and numbers, and
* complex objects, such as sequences of other elements.
*
* DER is a subset of BER (Basic Encoding Rules), with an emphasis on
* being non-ambiguous: there's always exactly one canonical way to
* encode a data structure defined in terms of ASN.1 using DER.
*
* This spec allows full parsing of format syntax, but to understand
* the semantics, one would typically require a dictionary of Object
* Identifiers (OIDs), to match OID bodies against some human-readable
* list of constants. OIDs are covered by many different standards,
* so typically it's simpler to use a pre-compiled list of them, such
* as:
*
* * <https://www.cs.auckland.ac.nz/~pgut001/dumpasn1.cfg>
* * <http://oid-info.com/>
* * <https://www.alvestrand.no/objectid/top.html>
*/
namespace {
class Asn1Der extends \Kaitai\Struct\Struct {
public function __construct(\Kaitai\Struct\Stream $_io, \Kaitai\Struct\Struct $_parent = null, \Asn1Der $_root = null) {
parent::__construct($_io, $_parent, $_root);
$this->_read();
}
private function _read() {
$this->_m_typeTag = $this->_io->readU1();
$this->_m_len = new \Asn1Der\LenEncoded($this->_io, $this, $this->_root);
switch ($this->typeTag()) {
case \Asn1Der\TypeTag::PRINTABLE_STRING:
$this->_m__raw_body = $this->_io->readBytes($this->len()->result());
$_io__raw_body = new \Kaitai\Struct\Stream($this->_m__raw_body);
$this->_m_body = new \Asn1Der\BodyPrintableString($_io__raw_body, $this, $this->_root);
break;
case \Asn1Der\TypeTag::SEQUENCE_10:
$this->_m__raw_body = $this->_io->readBytes($this->len()->result());
$_io__raw_body = new \Kaitai\Struct\Stream($this->_m__raw_body);
$this->_m_body = new \Asn1Der\BodySequence($_io__raw_body, $this, $this->_root);
break;
case \Asn1Der\TypeTag::SET:
$this->_m__raw_body = $this->_io->readBytes($this->len()->result());
$_io__raw_body = new \Kaitai\Struct\Stream($this->_m__raw_body);
$this->_m_body = new \Asn1Der\BodySequence($_io__raw_body, $this, $this->_root);
break;
case \Asn1Der\TypeTag::SEQUENCE_30:
$this->_m__raw_body = $this->_io->readBytes($this->len()->result());
$_io__raw_body = new \Kaitai\Struct\Stream($this->_m__raw_body);
$this->_m_body = new \Asn1Der\BodySequence($_io__raw_body, $this, $this->_root);
break;
case \Asn1Der\TypeTag::UTF8STRING:
$this->_m__raw_body = $this->_io->readBytes($this->len()->result());
$_io__raw_body = new \Kaitai\Struct\Stream($this->_m__raw_body);
$this->_m_body = new \Asn1Der\BodyUtf8string($_io__raw_body, $this, $this->_root);
break;
case \Asn1Der\TypeTag::OBJECT_ID:
$this->_m__raw_body = $this->_io->readBytes($this->len()->result());
$_io__raw_body = new \Kaitai\Struct\Stream($this->_m__raw_body);
$this->_m_body = new \Asn1Der\BodyObjectId($_io__raw_body, $this, $this->_root);
break;
default:
$this->_m_body = $this->_io->readBytes($this->len()->result());
break;
}
}
protected $_m_typeTag;
protected $_m_len;
protected $_m_body;
protected $_m__raw_body;
public function typeTag() { return $this->_m_typeTag; }
public function len() { return $this->_m_len; }
public function body() { return $this->_m_body; }
public function _raw_body() { return $this->_m__raw_body; }
}
}
namespace Asn1Der {
class BodySequence extends \Kaitai\Struct\Struct {
public function __construct(\Kaitai\Struct\Stream $_io, \Asn1Der $_parent = null, \Asn1Der $_root = null) {
parent::__construct($_io, $_parent, $_root);
$this->_read();
}
private function _read() {
$this->_m_entries = [];
$i = 0;
while (!$this->_io->isEof()) {
$this->_m_entries[] = new \Asn1Der($this->_io);
$i++;
}
}
protected $_m_entries;
public function entries() { return $this->_m_entries; }
}
}
namespace Asn1Der {
class BodyUtf8string extends \Kaitai\Struct\Struct {
public function __construct(\Kaitai\Struct\Stream $_io, \Asn1Der $_parent = null, \Asn1Der $_root = null) {
parent::__construct($_io, $_parent, $_root);
$this->_read();
}
private function _read() {
$this->_m_str = \Kaitai\Struct\Stream::bytesToStr($this->_io->readBytesFull(), "UTF-8");
}
protected $_m_str;
public function str() { return $this->_m_str; }
}
}
namespace Asn1Der {
class BodyObjectId extends \Kaitai\Struct\Struct {
public function __construct(\Kaitai\Struct\Stream $_io, \Asn1Der $_parent = null, \Asn1Der $_root = null) {
parent::__construct($_io, $_parent, $_root);
$this->_read();
}
private function _read() {
$this->_m_firstAndSecond = $this->_io->readU1();
$this->_m_rest = $this->_io->readBytesFull();
}
protected $_m_first;
public function first() {
if ($this->_m_first !== null)
return $this->_m_first;
$this->_m_first = intval($this->firstAndSecond() / 40);
return $this->_m_first;
}
protected $_m_second;
public function second() {
if ($this->_m_second !== null)
return $this->_m_second;
$this->_m_second = \Kaitai\Struct\Stream::mod($this->firstAndSecond(), 40);
return $this->_m_second;
}
protected $_m_firstAndSecond;
protected $_m_rest;
public function firstAndSecond() { return $this->_m_firstAndSecond; }
public function rest() { return $this->_m_rest; }
}
}
namespace Asn1Der {
class LenEncoded extends \Kaitai\Struct\Struct {
public function __construct(\Kaitai\Struct\Stream $_io, \Asn1Der $_parent = null, \Asn1Der $_root = null) {
parent::__construct($_io, $_parent, $_root);
$this->_read();
}
private function _read() {
$this->_m_b1 = $this->_io->readU1();
if ($this->b1() == 130) {
$this->_m_int2 = $this->_io->readU2be();
}
if ($this->b1() == 129) {
$this->_m_int1 = $this->_io->readU1();
}
}
protected $_m_result;
public function result() {
if ($this->_m_result !== null)
return $this->_m_result;
$this->_m_result = ($this->b1() == 129 ? $this->int1() : ($this->b1() == 130 ? $this->int2() : $this->b1()));
return $this->_m_result;
}
protected $_m_b1;
protected $_m_int2;
protected $_m_int1;
public function b1() { return $this->_m_b1; }
public function int2() { return $this->_m_int2; }
public function int1() { return $this->_m_int1; }
}
}
namespace Asn1Der {
class BodyPrintableString extends \Kaitai\Struct\Struct {
public function __construct(\Kaitai\Struct\Stream $_io, \Asn1Der $_parent = null, \Asn1Der $_root = null) {
parent::__construct($_io, $_parent, $_root);
$this->_read();
}
private function _read() {
$this->_m_str = \Kaitai\Struct\Stream::bytesToStr($this->_io->readBytesFull(), "ASCII");
}
protected $_m_str;
public function str() { return $this->_m_str; }
}
}
namespace Asn1Der {
class TypeTag {
const END_OF_CONTENT = 0;
const BOOLEAN = 1;
const INTEGER = 2;
const BIT_STRING = 3;
const OCTET_STRING = 4;
const NULL_VALUE = 5;
const OBJECT_ID = 6;
const OBJECT_DESCRIPTOR = 7;
const EXTERNAL = 8;
const REAL = 9;
const ENUMERATED = 10;
const EMBEDDED_PDV = 11;
const UTF8STRING = 12;
const RELATIVE_OID = 13;
const SEQUENCE_10 = 16;
const PRINTABLE_STRING = 19;
const IA5STRING = 22;
const SEQUENCE_30 = 48;
const SET = 49;
}
}