340 lines
11 KiB
PHP
340 lines
11 KiB
PHP
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<?php
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/*
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* This file is part of the PHPASN1 library.
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*
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* Copyright © Friedrich Große <friedrich.grosse@gmail.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace FG\ASN1;
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use Exception;
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/**
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* The Identifier encodes the ASN.1 tag (class and number) of the type of a data value.
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*
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* Every identifier whose number is in the range 0 to 30 has the following structure:
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*
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* Bits: 8 7 6 5 4 3 2 1
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* | Class | P/C | Tag number |
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* Bits 8 and 7 define the class of this type ( Universal, Application, Context-specific or Private).
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* Bit 6 encoded whether this type is primitive or constructed
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* The remaining bits 5 - 1 encode the tag number
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*/
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class Identifier
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{
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const CLASS_UNIVERSAL = 0x00;
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const CLASS_APPLICATION = 0x01;
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const CLASS_CONTEXT_SPECIFIC = 0x02;
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const CLASS_PRIVATE = 0x03;
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const EOC = 0x00; // unsupported for now
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const BOOLEAN = 0x01;
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const INTEGER = 0x02;
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const BITSTRING = 0x03;
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const OCTETSTRING = 0x04;
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const NULL = 0x05;
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const OBJECT_IDENTIFIER = 0x06;
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const OBJECT_DESCRIPTOR = 0x07;
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const EXTERNAL = 0x08; // unsupported for now
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const REAL = 0x09; // unsupported for now
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const ENUMERATED = 0x0A;
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const EMBEDDED_PDV = 0x0B; // unsupported for now
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const UTF8_STRING = 0x0C;
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const RELATIVE_OID = 0x0D;
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// value 0x0E and 0x0F are reserved for future use
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const SEQUENCE = 0x30;
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const SET = 0x31;
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const NUMERIC_STRING = 0x12;
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const PRINTABLE_STRING = 0x13;
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const T61_STRING = 0x14; // sometimes referred to as TeletextString
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const VIDEOTEXT_STRING = 0x15;
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const IA5_STRING = 0x16;
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const UTC_TIME = 0x17;
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const GENERALIZED_TIME = 0x18;
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const GRAPHIC_STRING = 0x19;
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const VISIBLE_STRING = 0x1A;
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const GENERAL_STRING = 0x1B;
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const UNIVERSAL_STRING = 0x1C;
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const CHARACTER_STRING = 0x1D; // Unrestricted character type
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const BMP_STRING = 0x1E;
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const LONG_FORM = 0x1F;
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const IS_CONSTRUCTED = 0x20;
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/**
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* Creates an identifier. Short form identifiers are returned as integers
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* for BC, long form identifiers will be returned as a string of octets.
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*
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* @param int $class
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* @param bool $isConstructed
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* @param int $tagNumber
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*
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* @throws Exception if the given arguments are invalid
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*
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* @return int|string
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*/
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public static function create($class, $isConstructed, $tagNumber)
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{
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if (!is_numeric($class) || $class < self::CLASS_UNIVERSAL || $class > self::CLASS_PRIVATE) {
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throw new Exception(sprintf('Invalid class %d given', $class));
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}
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if (!is_bool($isConstructed)) {
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throw new Exception("\$isConstructed must be a boolean value ($isConstructed given)");
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}
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$tagNumber = self::makeNumeric($tagNumber);
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if ($tagNumber < 0) {
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throw new Exception(sprintf('Invalid $tagNumber %d given. You can only use positive integers.', $tagNumber));
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}
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if ($tagNumber < self::LONG_FORM) {
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return ($class << 6) | ($isConstructed << 5) | $tagNumber;
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}
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$firstOctet = ($class << 6) | ($isConstructed << 5) | self::LONG_FORM;
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// Tag numbers formatted in long form are base-128 encoded. See X.609#8.1.2.4
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return chr($firstOctet).Base128::encode($tagNumber);
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}
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public static function isConstructed($identifierOctet)
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{
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return ($identifierOctet & self::IS_CONSTRUCTED) === self::IS_CONSTRUCTED;
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}
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public static function isLongForm($identifierOctet)
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{
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return ($identifierOctet & self::LONG_FORM) === self::LONG_FORM;
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}
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/**
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* Return the name of the mapped ASN.1 type with a preceding "ASN.1 ".
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*
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* Example: ASN.1 Octet String
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*
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* @see Identifier::getShortName()
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*
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* @param int|string $identifier
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*
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* @return string
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*/
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public static function getName($identifier)
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{
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$identifierOctet = self::makeNumeric($identifier);
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$typeName = static::getShortName($identifier);
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if (($identifierOctet & self::LONG_FORM) < self::LONG_FORM) {
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$typeName = "ASN.1 {$typeName}";
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}
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return $typeName;
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}
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/**
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* Return the short version of the type name.
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*
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* If the given identifier octet can be mapped to a known universal type this will
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* return its name. Else Identifier::getClassDescription() is used to retrieve
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* information about the identifier.
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*
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* @see Identifier::getName()
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* @see Identifier::getClassDescription()
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*
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* @param int|string $identifier
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*
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* @return string
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*/
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public static function getShortName($identifier)
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{
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$identifierOctet = self::makeNumeric($identifier);
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switch ($identifierOctet) {
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case self::EOC:
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return 'End-of-contents octet';
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case self::BOOLEAN:
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return 'Boolean';
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case self::INTEGER:
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return 'Integer';
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case self::BITSTRING:
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return 'Bit String';
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case self::OCTETSTRING:
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return 'Octet String';
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case self::NULL:
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return 'NULL';
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case self::OBJECT_IDENTIFIER:
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return 'Object Identifier';
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case self::OBJECT_DESCRIPTOR:
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return 'Object Descriptor';
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case self::EXTERNAL:
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return 'External Type';
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case self::REAL:
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return 'Real';
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case self::ENUMERATED:
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return 'Enumerated';
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case self::EMBEDDED_PDV:
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return 'Embedded PDV';
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case self::UTF8_STRING:
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return 'UTF8 String';
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case self::RELATIVE_OID:
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return 'Relative OID';
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case self::SEQUENCE:
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return 'Sequence';
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case self::SET:
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return 'Set';
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case self::NUMERIC_STRING:
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return 'Numeric String';
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case self::PRINTABLE_STRING:
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return 'Printable String';
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case self::T61_STRING:
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return 'T61 String';
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case self::VIDEOTEXT_STRING:
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return 'Videotext String';
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case self::IA5_STRING:
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return 'IA5 String';
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case self::UTC_TIME:
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return 'UTC Time';
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case self::GENERALIZED_TIME:
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return 'Generalized Time';
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case self::GRAPHIC_STRING:
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return 'Graphic String';
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case self::VISIBLE_STRING:
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return 'Visible String';
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case self::GENERAL_STRING:
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return 'General String';
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case self::UNIVERSAL_STRING:
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return 'Universal String';
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case self::CHARACTER_STRING:
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return 'Character String';
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case self::BMP_STRING:
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return 'BMP String';
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case 0x0E:
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return 'RESERVED (0x0E)';
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case 0x0F:
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return 'RESERVED (0x0F)';
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case self::LONG_FORM:
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default:
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$classDescription = self::getClassDescription($identifier);
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if (is_int($identifier)) {
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$identifier = chr($identifier);
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}
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return "$classDescription (0x".strtoupper(bin2hex($identifier)).')';
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}
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}
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/**
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* Returns a textual description of the information encoded in a given identifier octet.
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*
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* The first three (most significant) bytes are evaluated to determine if this is a
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* constructed or primitive type and if it is either universal, application, context-specific or
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* private.
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*
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* Example:
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* Constructed context-specific
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* Primitive universal
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*
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* @param int|string $identifier
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*
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* @return string
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*/
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public static function getClassDescription($identifier)
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{
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$identifierOctet = self::makeNumeric($identifier);
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if (self::isConstructed($identifierOctet)) {
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$classDescription = 'Constructed ';
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} else {
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$classDescription = 'Primitive ';
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}
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$classBits = $identifierOctet >> 6;
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switch ($classBits) {
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case self::CLASS_UNIVERSAL:
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$classDescription .= 'universal';
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break;
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case self::CLASS_APPLICATION:
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$classDescription .= 'application';
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break;
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case self::CLASS_CONTEXT_SPECIFIC:
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$tagNumber = self::getTagNumber($identifier);
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$classDescription = "[$tagNumber] Context-specific";
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break;
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case self::CLASS_PRIVATE:
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$classDescription .= 'private';
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break;
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default:
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return "INVALID IDENTIFIER OCTET: {$identifierOctet}";
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}
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return $classDescription;
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}
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/**
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* @param int|string $identifier
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*
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* @return int
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*/
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public static function getTagNumber($identifier)
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{
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$firstOctet = self::makeNumeric($identifier);
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$tagNumber = $firstOctet & self::LONG_FORM;
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if ($tagNumber < self::LONG_FORM) {
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return $tagNumber;
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}
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if (is_numeric($identifier)) {
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$identifier = chr($identifier);
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}
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return Base128::decode(substr($identifier, 1));
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}
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public static function isUniversalClass($identifier)
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{
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$identifier = self::makeNumeric($identifier);
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return $identifier >> 6 == self::CLASS_UNIVERSAL;
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}
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public static function isApplicationClass($identifier)
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{
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$identifier = self::makeNumeric($identifier);
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return $identifier >> 6 == self::CLASS_APPLICATION;
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}
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public static function isContextSpecificClass($identifier)
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{
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$identifier = self::makeNumeric($identifier);
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return $identifier >> 6 == self::CLASS_CONTEXT_SPECIFIC;
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}
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public static function isPrivateClass($identifier)
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{
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$identifier = self::makeNumeric($identifier);
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return $identifier >> 6 == self::CLASS_PRIVATE;
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}
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private static function makeNumeric($identifierOctet)
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{
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if (!is_numeric($identifierOctet)) {
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return ord($identifierOctet);
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} else {
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return $identifierOctet;
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}
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}
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}
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