sop / asn1

lib/ASN1/Feature/ElementBase.php

Indentation +78 added lines, -78 removed lines

@@ -13,90 +13,90 @@
  */
 interface ElementBase extends Encodable
 {
-    /**
-     * Get the class of the ASN.1 type.
-     *
-     * One of `Identifier::CLASS_*` constants.
-     *
-     * @return int
-     */
-    public function typeClass(): int;
+	/**
+	 * Get the class of the ASN.1 type.
+	 *
+	 * One of `Identifier::CLASS_*` constants.
+	 *
+	 * @return int
+	 */
+	public function typeClass(): int;
 
-    /**
-     * Check whether the element is constructed.
-     *
-     * Otherwise it's primitive.
-     *
-     * @return bool
-     */
-    public function isConstructed(): bool;
+	/**
+	 * Check whether the element is constructed.
+	 *
+	 * Otherwise it's primitive.
+	 *
+	 * @return bool
+	 */
+	public function isConstructed(): bool;
 
-    /**
-     * Get the tag of the element.
-     *
-     * Interpretation of the tag depends on the context. For example it may
-     * represent a universal type tag or a tag of an implicitly or explicitly
-     * tagged type.
-     *
-     * @return int
-     */
-    public function tag(): int;
+	/**
+	 * Get the tag of the element.
+	 *
+	 * Interpretation of the tag depends on the context. For example it may
+	 * represent a universal type tag or a tag of an implicitly or explicitly
+	 * tagged type.
+	 *
+	 * @return int
+	 */
+	public function tag(): int;
 
-    /**
-     * Check whether the element is a type of a given tag.
-     *
-     * @param int $tag Type tag
-     *
-     * @return bool
-     */
-    public function isType(int $tag): bool;
+	/**
+	 * Check whether the element is a type of a given tag.
+	 *
+	 * @param int $tag Type tag
+	 *
+	 * @return bool
+	 */
+	public function isType(int $tag): bool;
 
-    /**
-     * Check whether the element is a type of a given tag.
-     *
-     * Throws an exception if expectation fails.
-     *
-     * @param int $tag Type tag
-     *
-     * @throws \UnexpectedValueException If the element type differs from the expected
-     *
-     * @return ElementBase
-     */
-    public function expectType(int $tag): ElementBase;
+	/**
+	 * Check whether the element is a type of a given tag.
+	 *
+	 * Throws an exception if expectation fails.
+	 *
+	 * @param int $tag Type tag
+	 *
+	 * @throws \UnexpectedValueException If the element type differs from the expected
+	 *
+	 * @return ElementBase
+	 */
+	public function expectType(int $tag): ElementBase;
 
-    /**
-     * Check whether the element is tagged (context specific).
-     *
-     * @return bool
-     */
-    public function isTagged(): bool;
+	/**
+	 * Check whether the element is tagged (context specific).
+	 *
+	 * @return bool
+	 */
+	public function isTagged(): bool;
 
-    /**
-     * Check whether the element is tagged (context specific) and optionally has
-     * a given tag.
-     *
-     * Throws an exception if the element is not tagged or tag differs from
-     * the expected.
-     *
-     * @param null|int $tag Optional type tag
-     *
-     * @throws \UnexpectedValueException If expectation fails
-     *
-     * @return TaggedType
-     */
-    public function expectTagged(?int $tag = null): TaggedType;
+	/**
+	 * Check whether the element is tagged (context specific) and optionally has
+	 * a given tag.
+	 *
+	 * Throws an exception if the element is not tagged or tag differs from
+	 * the expected.
+	 *
+	 * @param null|int $tag Optional type tag
+	 *
+	 * @throws \UnexpectedValueException If expectation fails
+	 *
+	 * @return TaggedType
+	 */
+	public function expectTagged(?int $tag = null): TaggedType;
 
-    /**
-     * Get the object as an abstract Element instance.
-     *
-     * @return Element
-     */
-    public function asElement(): Element;
+	/**
+	 * Get the object as an abstract Element instance.
+	 *
+	 * @return Element
+	 */
+	public function asElement(): Element;
 
-    /**
-     * Get the object as an UnspecifiedType instance.
-     *
-     * @return UnspecifiedType
-     */
-    public function asUnspecified(): UnspecifiedType;
+	/**
+	 * Get the object as an UnspecifiedType instance.
+	 *
+	 * @return UnspecifiedType
+	 */
+	public function asUnspecified(): UnspecifiedType;
 }

lib/ASN1/Component/Identifier.php

Indentation +275 added lines, -275 removed lines

@@ -13,301 +13,301 @@
  */
 class Identifier implements Encodable
 {
-    // Type class enumerations
-    const CLASS_UNIVERSAL = 0b00;
-    const CLASS_APPLICATION = 0b01;
-    const CLASS_CONTEXT_SPECIFIC = 0b10;
-    const CLASS_PRIVATE = 0b11;
+	// Type class enumerations
+	const CLASS_UNIVERSAL = 0b00;
+	const CLASS_APPLICATION = 0b01;
+	const CLASS_CONTEXT_SPECIFIC = 0b10;
+	const CLASS_PRIVATE = 0b11;
 
-    /**
-     * Mapping from type class to human readable name.
-     *
-     * @internal
-     *
-     * @var array
-     */
-    const MAP_CLASS_TO_NAME = [
-        self::CLASS_UNIVERSAL => 'UNIVERSAL',
-        self::CLASS_APPLICATION => 'APPLICATION',
-        self::CLASS_CONTEXT_SPECIFIC => 'CONTEXT SPECIFIC',
-        self::CLASS_PRIVATE => 'PRIVATE',
-    ];
+	/**
+	 * Mapping from type class to human readable name.
+	 *
+	 * @internal
+	 *
+	 * @var array
+	 */
+	const MAP_CLASS_TO_NAME = [
+		self::CLASS_UNIVERSAL => 'UNIVERSAL',
+		self::CLASS_APPLICATION => 'APPLICATION',
+		self::CLASS_CONTEXT_SPECIFIC => 'CONTEXT SPECIFIC',
+		self::CLASS_PRIVATE => 'PRIVATE',
+	];
 
-    // P/C enumerations
-    const PRIMITIVE = 0b0;
-    const CONSTRUCTED = 0b1;
+	// P/C enumerations
+	const PRIMITIVE = 0b0;
+	const CONSTRUCTED = 0b1;
 
-    /**
-     * Type class.
-     *
-     * @var int
-     */
-    private $_class;
+	/**
+	 * Type class.
+	 *
+	 * @var int
+	 */
+	private $_class;
 
-    /**
-     * Primitive or Constructed.
-     *
-     * @var int
-     */
-    private $_pc;
+	/**
+	 * Primitive or Constructed.
+	 *
+	 * @var int
+	 */
+	private $_pc;
 
-    /**
-     * Content type tag.
-     *
-     * @var BigInt
-     */
-    private $_tag;
+	/**
+	 * Content type tag.
+	 *
+	 * @var BigInt
+	 */
+	private $_tag;
 
-    /**
-     * Constructor.
-     *
-     * @param int        $class Type class
-     * @param int        $pc    Primitive / Constructed
-     * @param int|string $tag   Type tag number
-     */
-    public function __construct(int $class, int $pc, $tag)
-    {
-        $this->_class = 0b11 & $class;
-        $this->_pc = 0b1 & $pc;
-        $this->_tag = new BigInt($tag);
-    }
+	/**
+	 * Constructor.
+	 *
+	 * @param int        $class Type class
+	 * @param int        $pc    Primitive / Constructed
+	 * @param int|string $tag   Type tag number
+	 */
+	public function __construct(int $class, int $pc, $tag)
+	{
+		$this->_class = 0b11 & $class;
+		$this->_pc = 0b1 & $pc;
+		$this->_tag = new BigInt($tag);
+	}
 
-    /**
-     * Decode identifier component from DER data.
-     *
-     * @param string   $data   DER encoded data
-     * @param null|int $offset Reference to the variable that contains offset
-     *                         into the data where to start parsing.
-     *                         Variable is updated to the offset next to the
-     *                         parsed identifier. If null, start from offset 0.
-     *
-     * @throws DecodeException If decoding fails
-     *
-     * @return self
-     */
-    public static function fromDER(string $data, int &$offset = null): Identifier
-    {
-        $idx = $offset ?? 0;
-        $datalen = strlen($data);
-        if ($idx >= $datalen) {
-            throw new DecodeException('Invalid offset.');
-        }
-        $byte = ord($data[$idx++]);
-        // bits 8 and 7 (class)
-        // 0 = universal, 1 = application, 2 = context-specific, 3 = private
-        $class = (0b11000000 & $byte) >> 6;
-        // bit 6 (0 = primitive / 1 = constructed)
-        $pc = (0b00100000 & $byte) >> 5;
-        // bits 5 to 1 (tag number)
-        $tag = (0b00011111 & $byte);
-        // long-form identifier
-        if (0x1f === $tag) {
-            $tag = self::_decodeLongFormTag($data, $idx);
-        }
-        if (isset($offset)) {
-            $offset = $idx;
-        }
-        return new self($class, $pc, $tag);
-    }
+	/**
+	 * Decode identifier component from DER data.
+	 *
+	 * @param string   $data   DER encoded data
+	 * @param null|int $offset Reference to the variable that contains offset
+	 *                         into the data where to start parsing.
+	 *                         Variable is updated to the offset next to the
+	 *                         parsed identifier. If null, start from offset 0.
+	 *
+	 * @throws DecodeException If decoding fails
+	 *
+	 * @return self
+	 */
+	public static function fromDER(string $data, int &$offset = null): Identifier
+	{
+		$idx = $offset ?? 0;
+		$datalen = strlen($data);
+		if ($idx >= $datalen) {
+			throw new DecodeException('Invalid offset.');
+		}
+		$byte = ord($data[$idx++]);
+		// bits 8 and 7 (class)
+		// 0 = universal, 1 = application, 2 = context-specific, 3 = private
+		$class = (0b11000000 & $byte) >> 6;
+		// bit 6 (0 = primitive / 1 = constructed)
+		$pc = (0b00100000 & $byte) >> 5;
+		// bits 5 to 1 (tag number)
+		$tag = (0b00011111 & $byte);
+		// long-form identifier
+		if (0x1f === $tag) {
+			$tag = self::_decodeLongFormTag($data, $idx);
+		}
+		if (isset($offset)) {
+			$offset = $idx;
+		}
+		return new self($class, $pc, $tag);
+	}
 
-    /**
-     * {@inheritdoc}
-     */
-    public function toDER(): string
-    {
-        $bytes = [];
-        $byte = $this->_class << 6 | $this->_pc << 5;
-        $tag = $this->_tag->gmpObj();
-        if ($tag < 0x1f) {
-            $bytes[] = $byte | $tag;
-        }
-        // long-form identifier
-        else {
-            $bytes[] = $byte | 0x1f;
-            $octets = [];
-            for (; $tag > 0; $tag >>= 7) {
-                array_push($octets, gmp_intval(0x80 | ($tag & 0x7f)));
-            }
-            // last octet has bit 8 set to zero
-            $octets[0] &= 0x7f;
-            foreach (array_reverse($octets) as $octet) {
-                $bytes[] = $octet;
-            }
-        }
-        return pack('C*', ...$bytes);
-    }
+	/**
+	 * {@inheritdoc}
+	 */
+	public function toDER(): string
+	{
+		$bytes = [];
+		$byte = $this->_class << 6 | $this->_pc << 5;
+		$tag = $this->_tag->gmpObj();
+		if ($tag < 0x1f) {
+			$bytes[] = $byte | $tag;
+		}
+		// long-form identifier
+		else {
+			$bytes[] = $byte | 0x1f;
+			$octets = [];
+			for (; $tag > 0; $tag >>= 7) {
+				array_push($octets, gmp_intval(0x80 | ($tag & 0x7f)));
+			}
+			// last octet has bit 8 set to zero
+			$octets[0] &= 0x7f;
+			foreach (array_reverse($octets) as $octet) {
+				$bytes[] = $octet;
+			}
+		}
+		return pack('C*', ...$bytes);
+	}
 
-    /**
-     * Get class of the type.
-     *
-     * @return int
-     */
-    public function typeClass(): int
-    {
-        return $this->_class;
-    }
+	/**
+	 * Get class of the type.
+	 *
+	 * @return int
+	 */
+	public function typeClass(): int
+	{
+		return $this->_class;
+	}
 
-    /**
-     * Get P/C.
-     *
-     * @return int
-     */
-    public function pc(): int
-    {
-        return $this->_pc;
-    }
+	/**
+	 * Get P/C.
+	 *
+	 * @return int
+	 */
+	public function pc(): int
+	{
+		return $this->_pc;
+	}
 
-    /**
-     * Get the tag number.
-     *
-     * @return string Base 10 integer string
-     */
-    public function tag(): string
-    {
-        return $this->_tag->base10();
-    }
+	/**
+	 * Get the tag number.
+	 *
+	 * @return string Base 10 integer string
+	 */
+	public function tag(): string
+	{
+		return $this->_tag->base10();
+	}
 
-    /**
-     * Get the tag as an integer.
-     *
-     * @return int
-     */
-    public function intTag(): int
-    {
-        return $this->_tag->intVal();
-    }
+	/**
+	 * Get the tag as an integer.
+	 *
+	 * @return int
+	 */
+	public function intTag(): int
+	{
+		return $this->_tag->intVal();
+	}
 
-    /**
-     * Check whether type is of an universal class.
-     *
-     * @return bool
-     */
-    public function isUniversal(): bool
-    {
-        return self::CLASS_UNIVERSAL === $this->_class;
-    }
+	/**
+	 * Check whether type is of an universal class.
+	 *
+	 * @return bool
+	 */
+	public function isUniversal(): bool
+	{
+		return self::CLASS_UNIVERSAL === $this->_class;
+	}
 
-    /**
-     * Check whether type is of an application class.
-     *
-     * @return bool
-     */
-    public function isApplication(): bool
-    {
-        return self::CLASS_APPLICATION === $this->_class;
-    }
+	/**
+	 * Check whether type is of an application class.
+	 *
+	 * @return bool
+	 */
+	public function isApplication(): bool
+	{
+		return self::CLASS_APPLICATION === $this->_class;
+	}
 
-    /**
-     * Check whether type is of a context specific class.
-     *
-     * @return bool
-     */
-    public function isContextSpecific(): bool
-    {
-        return self::CLASS_CONTEXT_SPECIFIC === $this->_class;
-    }
+	/**
+	 * Check whether type is of a context specific class.
+	 *
+	 * @return bool
+	 */
+	public function isContextSpecific(): bool
+	{
+		return self::CLASS_CONTEXT_SPECIFIC === $this->_class;
+	}
 
-    /**
-     * Check whether type is of a private class.
-     *
-     * @return bool
-     */
-    public function isPrivate(): bool
-    {
-        return self::CLASS_PRIVATE === $this->_class;
-    }
+	/**
+	 * Check whether type is of a private class.
+	 *
+	 * @return bool
+	 */
+	public function isPrivate(): bool
+	{
+		return self::CLASS_PRIVATE === $this->_class;
+	}
 
-    /**
-     * Check whether content is primitive type.
-     *
-     * @return bool
-     */
-    public function isPrimitive(): bool
-    {
-        return self::PRIMITIVE === $this->_pc;
-    }
+	/**
+	 * Check whether content is primitive type.
+	 *
+	 * @return bool
+	 */
+	public function isPrimitive(): bool
+	{
+		return self::PRIMITIVE === $this->_pc;
+	}
 
-    /**
-     * Check hether content is constructed type.
-     *
-     * @return bool
-     */
-    public function isConstructed(): bool
-    {
-        return self::CONSTRUCTED === $this->_pc;
-    }
+	/**
+	 * Check hether content is constructed type.
+	 *
+	 * @return bool
+	 */
+	public function isConstructed(): bool
+	{
+		return self::CONSTRUCTED === $this->_pc;
+	}
 
-    /**
-     * Get self with given type class.
-     *
-     * @param int $class One of `CLASS_*` enumerations
-     *
-     * @return self
-     */
-    public function withClass(int $class): Identifier
-    {
-        $obj = clone $this;
-        $obj->_class = 0b11 & $class;
-        return $obj;
-    }
+	/**
+	 * Get self with given type class.
+	 *
+	 * @param int $class One of `CLASS_*` enumerations
+	 *
+	 * @return self
+	 */
+	public function withClass(int $class): Identifier
+	{
+		$obj = clone $this;
+		$obj->_class = 0b11 & $class;
+		return $obj;
+	}
 
-    /**
-     * Get self with given type tag.
-     *
-     * @param int|string $tag Tag number
-     *
-     * @return self
-     */
-    public function withTag($tag): Identifier
-    {
-        $obj = clone $this;
-        $obj->_tag = new BigInt($tag);
-        return $obj;
-    }
+	/**
+	 * Get self with given type tag.
+	 *
+	 * @param int|string $tag Tag number
+	 *
+	 * @return self
+	 */
+	public function withTag($tag): Identifier
+	{
+		$obj = clone $this;
+		$obj->_tag = new BigInt($tag);
+		return $obj;
+	}
 
-    /**
-     * Get human readable name of the type class.
-     *
-     * @param int $class
-     *
-     * @return string
-     */
-    public static function classToName(int $class): string
-    {
-        if (!array_key_exists($class, self::MAP_CLASS_TO_NAME)) {
-            return "CLASS {$class}";
-        }
-        return self::MAP_CLASS_TO_NAME[$class];
-    }
+	/**
+	 * Get human readable name of the type class.
+	 *
+	 * @param int $class
+	 *
+	 * @return string
+	 */
+	public static function classToName(int $class): string
+	{
+		if (!array_key_exists($class, self::MAP_CLASS_TO_NAME)) {
+			return "CLASS {$class}";
+		}
+		return self::MAP_CLASS_TO_NAME[$class];
+	}
 
-    /**
-     * Parse long form tag.
-     *
-     * @param string $data   DER data
-     * @param int    $offset Reference to the variable containing offset to data
-     *
-     * @throws DecodeException If decoding fails
-     *
-     * @return string Tag number
-     */
-    private static function _decodeLongFormTag(string $data, int &$offset): string
-    {
-        $datalen = strlen($data);
-        $tag = gmp_init(0, 10);
-        while (true) {
-            if ($offset >= $datalen) {
-                throw new DecodeException(
-                    'Unexpected end of data while decoding' .
-                    ' long form identifier.');
-            }
-            $byte = ord($data[$offset++]);
-            $tag <<= 7;
-            $tag |= 0x7f & $byte;
-            // last byte has bit 8 set to zero
-            if (!(0x80 & $byte)) {
-                break;
-            }
-        }
-        return gmp_strval($tag, 10);
-    }
+	/**
+	 * Parse long form tag.
+	 *
+	 * @param string $data   DER data
+	 * @param int    $offset Reference to the variable containing offset to data
+	 *
+	 * @throws DecodeException If decoding fails
+	 *
+	 * @return string Tag number
+	 */
+	private static function _decodeLongFormTag(string $data, int &$offset): string
+	{
+		$datalen = strlen($data);
+		$tag = gmp_init(0, 10);
+		while (true) {
+			if ($offset >= $datalen) {
+				throw new DecodeException(
+					'Unexpected end of data while decoding' .
+					' long form identifier.');
+			}
+			$byte = ord($data[$offset++]);
+			$tag <<= 7;
+			$tag |= 0x7f & $byte;
+			// last byte has bit 8 set to zero
+			if (!(0x80 & $byte)) {
+				break;
+			}
+		}
+		return gmp_strval($tag, 10);
+	}
 }

lib/ASN1/Type/UnspecifiedType.php

Indentation +670 added lines, -670 removed lines

@@ -17,674 +17,674 @@
  */
 class UnspecifiedType implements ElementBase
 {
-    /**
-     * The wrapped element.
-     *
-     * @var Element
-     */
-    private $_element;
-
-    /**
-     * Constructor.
-     *
-     * @param Element $el
-     */
-    public function __construct(Element $el)
-    {
-        $this->_element = $el;
-    }
-
-    /**
-     * Initialize from DER data.
-     *
-     * @param string $data DER encoded data
-     *
-     * @return self
-     */
-    public static function fromDER(string $data): self
-    {
-        return Element::fromDER($data)->asUnspecified();
-    }
-
-    /**
-     * Initialize from ElementBase interface.
-     *
-     * @param ElementBase $el
-     *
-     * @return self
-     */
-    public static function fromElementBase(ElementBase $el): self
-    {
-        // if element is already wrapped
-        if ($el instanceof self) {
-            return $el;
-        }
-        return new self($el->asElement());
-    }
-
-    /**
-     * Get the wrapped element as a context specific tagged type.
-     *
-     * @throws \UnexpectedValueException If the element is not tagged
-     *
-     * @return TaggedType
-     */
-    public function asTagged(): TaggedType
-    {
-        if (!$this->_element instanceof TaggedType) {
-            throw new \UnexpectedValueException(
-                'Tagged element expected, got ' . $this->_typeDescriptorString());
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as an application specific type.
-     *
-     * @throws \UnexpectedValueException If element is not application specific
-     *
-     * @return \Sop\ASN1\Type\Tagged\ApplicationType
-     */
-    public function asApplication(): Tagged\ApplicationType
-    {
-        if (!$this->_element instanceof Tagged\ApplicationType) {
-            throw new \UnexpectedValueException(
-                'Application type expected, got ' . $this->_typeDescriptorString());
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a private tagged type.
-     *
-     * @throws \UnexpectedValueException If element is not using private tagging
-     *
-     * @return \Sop\ASN1\Type\Tagged\PrivateType
-     */
-    public function asPrivate(): Tagged\PrivateType
-    {
-        if (!$this->_element instanceof Tagged\PrivateType) {
-            throw new \UnexpectedValueException(
-                'Private type expected, got ' . $this->_typeDescriptorString());
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a boolean type.
-     *
-     * @throws \UnexpectedValueException If the element is not a boolean
-     *
-     * @return \Sop\ASN1\Type\Primitive\Boolean
-     */
-    public function asBoolean(): Primitive\Boolean
-    {
-        if (!$this->_element instanceof Primitive\Boolean) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_BOOLEAN));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as an integer type.
-     *
-     * @throws \UnexpectedValueException If the element is not an integer
-     *
-     * @return \Sop\ASN1\Type\Primitive\Integer
-     */
-    public function asInteger(): Primitive\Integer
-    {
-        if (!$this->_element instanceof Primitive\Integer) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_INTEGER));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a bit string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a bit string
-     *
-     * @return \Sop\ASN1\Type\Primitive\BitString
-     */
-    public function asBitString(): Primitive\BitString
-    {
-        if (!$this->_element instanceof Primitive\BitString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_BIT_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as an octet string type.
-     *
-     * @throws \UnexpectedValueException If the element is not an octet string
-     *
-     * @return \Sop\ASN1\Type\Primitive\OctetString
-     */
-    public function asOctetString(): Primitive\OctetString
-    {
-        if (!$this->_element instanceof Primitive\OctetString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_OCTET_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a null type.
-     *
-     * @throws \UnexpectedValueException If the element is not a null
-     *
-     * @return \Sop\ASN1\Type\Primitive\NullType
-     */
-    public function asNull(): Primitive\NullType
-    {
-        if (!$this->_element instanceof Primitive\NullType) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_NULL));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as an object identifier type.
-     *
-     * @throws \UnexpectedValueException If the element is not an object identifier
-     *
-     * @return \Sop\ASN1\Type\Primitive\ObjectIdentifier
-     */
-    public function asObjectIdentifier(): Primitive\ObjectIdentifier
-    {
-        if (!$this->_element instanceof Primitive\ObjectIdentifier) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_OBJECT_IDENTIFIER));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as an object descriptor type.
-     *
-     * @throws \UnexpectedValueException If the element is not an object descriptor
-     *
-     * @return \Sop\ASN1\Type\Primitive\ObjectDescriptor
-     */
-    public function asObjectDescriptor(): Primitive\ObjectDescriptor
-    {
-        if (!$this->_element instanceof Primitive\ObjectDescriptor) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_OBJECT_DESCRIPTOR));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a real type.
-     *
-     * @throws \UnexpectedValueException If the element is not a real
-     *
-     * @return \Sop\ASN1\Type\Primitive\Real
-     */
-    public function asReal(): Primitive\Real
-    {
-        if (!$this->_element instanceof Primitive\Real) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_REAL));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as an enumerated type.
-     *
-     * @throws \UnexpectedValueException If the element is not an enumerated
-     *
-     * @return \Sop\ASN1\Type\Primitive\Enumerated
-     */
-    public function asEnumerated(): Primitive\Enumerated
-    {
-        if (!$this->_element instanceof Primitive\Enumerated) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_ENUMERATED));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a UTF8 string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a UTF8 string
-     *
-     * @return \Sop\ASN1\Type\Primitive\UTF8String
-     */
-    public function asUTF8String(): Primitive\UTF8String
-    {
-        if (!$this->_element instanceof Primitive\UTF8String) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_UTF8_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a relative OID type.
-     *
-     * @throws \UnexpectedValueException If the element is not a relative OID
-     *
-     * @return \Sop\ASN1\Type\Primitive\RelativeOID
-     */
-    public function asRelativeOID(): Primitive\RelativeOID
-    {
-        if (!$this->_element instanceof Primitive\RelativeOID) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_RELATIVE_OID));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a sequence type.
-     *
-     * @throws \UnexpectedValueException If the element is not a sequence
-     *
-     * @return \Sop\ASN1\Type\Constructed\Sequence
-     */
-    public function asSequence(): Constructed\Sequence
-    {
-        if (!$this->_element instanceof Constructed\Sequence) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_SEQUENCE));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a set type.
-     *
-     * @throws \UnexpectedValueException If the element is not a set
-     *
-     * @return \Sop\ASN1\Type\Constructed\Set
-     */
-    public function asSet(): Constructed\Set
-    {
-        if (!$this->_element instanceof Constructed\Set) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_SET));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a numeric string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a numeric string
-     *
-     * @return \Sop\ASN1\Type\Primitive\NumericString
-     */
-    public function asNumericString(): Primitive\NumericString
-    {
-        if (!$this->_element instanceof Primitive\NumericString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_NUMERIC_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a printable string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a printable
-     *                                   string
-     *
-     * @return \Sop\ASN1\Type\Primitive\PrintableString
-     */
-    public function asPrintableString(): Primitive\PrintableString
-    {
-        if (!$this->_element instanceof Primitive\PrintableString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_PRINTABLE_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a T61 string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a T61 string
-     *
-     * @return \Sop\ASN1\Type\Primitive\T61String
-     */
-    public function asT61String(): Primitive\T61String
-    {
-        if (!$this->_element instanceof Primitive\T61String) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_T61_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a videotex string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a videotex string
-     *
-     * @return \Sop\ASN1\Type\Primitive\VideotexString
-     */
-    public function asVideotexString(): Primitive\VideotexString
-    {
-        if (!$this->_element instanceof Primitive\VideotexString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_VIDEOTEX_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a IA5 string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a IA5 string
-     *
-     * @return \Sop\ASN1\Type\Primitive\IA5String
-     */
-    public function asIA5String(): Primitive\IA5String
-    {
-        if (!$this->_element instanceof Primitive\IA5String) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_IA5_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as an UTC time type.
-     *
-     * @throws \UnexpectedValueException If the element is not a UTC time
-     *
-     * @return \Sop\ASN1\Type\Primitive\UTCTime
-     */
-    public function asUTCTime(): Primitive\UTCTime
-    {
-        if (!$this->_element instanceof Primitive\UTCTime) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_UTC_TIME));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a generalized time type.
-     *
-     * @throws \UnexpectedValueException If the element is not a generalized time
-     *
-     * @return \Sop\ASN1\Type\Primitive\GeneralizedTime
-     */
-    public function asGeneralizedTime(): Primitive\GeneralizedTime
-    {
-        if (!$this->_element instanceof Primitive\GeneralizedTime) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_GENERALIZED_TIME));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a graphic string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a graphic string
-     *
-     * @return \Sop\ASN1\Type\Primitive\GraphicString
-     */
-    public function asGraphicString(): Primitive\GraphicString
-    {
-        if (!$this->_element instanceof Primitive\GraphicString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_GRAPHIC_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a visible string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a visible string
-     *
-     * @return \Sop\ASN1\Type\Primitive\VisibleString
-     */
-    public function asVisibleString(): Primitive\VisibleString
-    {
-        if (!$this->_element instanceof Primitive\VisibleString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_VISIBLE_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a general string type.
-     *
-     * @throws \UnexpectedValueException If the element is not general string
-     *
-     * @return \Sop\ASN1\Type\Primitive\GeneralString
-     */
-    public function asGeneralString(): Primitive\GeneralString
-    {
-        if (!$this->_element instanceof Primitive\GeneralString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_GENERAL_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a universal string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a universal string
-     *
-     * @return \Sop\ASN1\Type\Primitive\UniversalString
-     */
-    public function asUniversalString(): Primitive\UniversalString
-    {
-        if (!$this->_element instanceof Primitive\UniversalString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_UNIVERSAL_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a character string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a character string
-     *
-     * @return \Sop\ASN1\Type\Primitive\CharacterString
-     */
-    public function asCharacterString(): Primitive\CharacterString
-    {
-        if (!$this->_element instanceof Primitive\CharacterString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_CHARACTER_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a BMP string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a bmp string
-     *
-     * @return \Sop\ASN1\Type\Primitive\BMPString
-     */
-    public function asBMPString(): Primitive\BMPString
-    {
-        if (!$this->_element instanceof Primitive\BMPString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_BMP_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as a constructed string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a constructed string
-     *
-     * @return \Sop\ASN1\Type\Constructed\ConstructedString
-     */
-    public function asConstructedString(): Constructed\ConstructedString
-    {
-        if (!$this->_element instanceof Constructed\ConstructedString) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_CONSTRUCTED_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as any string type.
-     *
-     * @throws \UnexpectedValueException If the element is not a string
-     *
-     * @return StringType
-     */
-    public function asString(): StringType
-    {
-        if (!$this->_element instanceof StringType) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_STRING));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * Get the wrapped element as any time type.
-     *
-     * @throws \UnexpectedValueException If the element is not a time
-     *
-     * @return TimeType
-     */
-    public function asTime(): TimeType
-    {
-        if (!$this->_element instanceof TimeType) {
-            throw new \UnexpectedValueException(
-                $this->_generateExceptionMessage(Element::TYPE_TIME));
-        }
-        return $this->_element;
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function toDER(): string
-    {
-        return $this->_element->toDER();
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function typeClass(): int
-    {
-        return $this->_element->typeClass();
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function isConstructed(): bool
-    {
-        return $this->_element->isConstructed();
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function tag(): int
-    {
-        return $this->_element->tag();
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function isType(int $tag): bool
-    {
-        return $this->_element->isType($tag);
-    }
-
-    /**
-     * {@inheritdoc}
-     *
-     * Consider using any of the `as*` accessor methods instead.
-     */
-    public function expectType(int $tag): ElementBase
-    {
-        return $this->_element->expectType($tag);
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function isTagged(): bool
-    {
-        return $this->_element->isTagged();
-    }
-
-    /**
-     * {@inheritdoc}
-     *
-     * Consider using `asTagged()` method instead and chaining
-     * with `TaggedType::asExplicit()` or `TaggedType::asImplicit()`.
-     */
-    public function expectTagged(?int $tag = null): TaggedType
-    {
-        return $this->_element->expectTagged($tag);
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function asElement(): Element
-    {
-        return $this->_element;
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function asUnspecified(): UnspecifiedType
-    {
-        return $this;
-    }
-
-    /**
-     * Generate message for exceptions thrown by `as*` methods.
-     *
-     * @param int $tag Type tag of the expected element
-     *
-     * @return string
-     */
-    private function _generateExceptionMessage(int $tag): string
-    {
-        return sprintf('%s expected, got %s.', Element::tagToName($tag),
-            $this->_typeDescriptorString());
-    }
-
-    /**
-     * Get textual description of the wrapped element for debugging purposes.
-     *
-     * @return string
-     */
-    private function _typeDescriptorString(): string
-    {
-        $type_cls = $this->_element->typeClass();
-        $tag = $this->_element->tag();
-        if (Identifier::CLASS_UNIVERSAL === $type_cls) {
-            return Element::tagToName($tag);
-        }
-        return Identifier::classToName($type_cls) . " TAG {$tag}";
-    }
+	/**
+	 * The wrapped element.
+	 *
+	 * @var Element
+	 */
+	private $_element;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param Element $el
+	 */
+	public function __construct(Element $el)
+	{
+		$this->_element = $el;
+	}
+
+	/**
+	 * Initialize from DER data.
+	 *
+	 * @param string $data DER encoded data
+	 *
+	 * @return self
+	 */
+	public static function fromDER(string $data): self
+	{
+		return Element::fromDER($data)->asUnspecified();
+	}
+
+	/**
+	 * Initialize from ElementBase interface.
+	 *
+	 * @param ElementBase $el
+	 *
+	 * @return self
+	 */
+	public static function fromElementBase(ElementBase $el): self
+	{
+		// if element is already wrapped
+		if ($el instanceof self) {
+			return $el;
+		}
+		return new self($el->asElement());
+	}
+
+	/**
+	 * Get the wrapped element as a context specific tagged type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not tagged
+	 *
+	 * @return TaggedType
+	 */
+	public function asTagged(): TaggedType
+	{
+		if (!$this->_element instanceof TaggedType) {
+			throw new \UnexpectedValueException(
+				'Tagged element expected, got ' . $this->_typeDescriptorString());
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as an application specific type.
+	 *
+	 * @throws \UnexpectedValueException If element is not application specific
+	 *
+	 * @return \Sop\ASN1\Type\Tagged\ApplicationType
+	 */
+	public function asApplication(): Tagged\ApplicationType
+	{
+		if (!$this->_element instanceof Tagged\ApplicationType) {
+			throw new \UnexpectedValueException(
+				'Application type expected, got ' . $this->_typeDescriptorString());
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a private tagged type.
+	 *
+	 * @throws \UnexpectedValueException If element is not using private tagging
+	 *
+	 * @return \Sop\ASN1\Type\Tagged\PrivateType
+	 */
+	public function asPrivate(): Tagged\PrivateType
+	{
+		if (!$this->_element instanceof Tagged\PrivateType) {
+			throw new \UnexpectedValueException(
+				'Private type expected, got ' . $this->_typeDescriptorString());
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a boolean type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a boolean
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\Boolean
+	 */
+	public function asBoolean(): Primitive\Boolean
+	{
+		if (!$this->_element instanceof Primitive\Boolean) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_BOOLEAN));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as an integer type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not an integer
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\Integer
+	 */
+	public function asInteger(): Primitive\Integer
+	{
+		if (!$this->_element instanceof Primitive\Integer) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_INTEGER));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a bit string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a bit string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\BitString
+	 */
+	public function asBitString(): Primitive\BitString
+	{
+		if (!$this->_element instanceof Primitive\BitString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_BIT_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as an octet string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not an octet string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\OctetString
+	 */
+	public function asOctetString(): Primitive\OctetString
+	{
+		if (!$this->_element instanceof Primitive\OctetString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_OCTET_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a null type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a null
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\NullType
+	 */
+	public function asNull(): Primitive\NullType
+	{
+		if (!$this->_element instanceof Primitive\NullType) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_NULL));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as an object identifier type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not an object identifier
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\ObjectIdentifier
+	 */
+	public function asObjectIdentifier(): Primitive\ObjectIdentifier
+	{
+		if (!$this->_element instanceof Primitive\ObjectIdentifier) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_OBJECT_IDENTIFIER));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as an object descriptor type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not an object descriptor
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\ObjectDescriptor
+	 */
+	public function asObjectDescriptor(): Primitive\ObjectDescriptor
+	{
+		if (!$this->_element instanceof Primitive\ObjectDescriptor) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_OBJECT_DESCRIPTOR));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a real type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a real
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\Real
+	 */
+	public function asReal(): Primitive\Real
+	{
+		if (!$this->_element instanceof Primitive\Real) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_REAL));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as an enumerated type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not an enumerated
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\Enumerated
+	 */
+	public function asEnumerated(): Primitive\Enumerated
+	{
+		if (!$this->_element instanceof Primitive\Enumerated) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_ENUMERATED));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a UTF8 string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a UTF8 string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\UTF8String
+	 */
+	public function asUTF8String(): Primitive\UTF8String
+	{
+		if (!$this->_element instanceof Primitive\UTF8String) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_UTF8_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a relative OID type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a relative OID
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\RelativeOID
+	 */
+	public function asRelativeOID(): Primitive\RelativeOID
+	{
+		if (!$this->_element instanceof Primitive\RelativeOID) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_RELATIVE_OID));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a sequence type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a sequence
+	 *
+	 * @return \Sop\ASN1\Type\Constructed\Sequence
+	 */
+	public function asSequence(): Constructed\Sequence
+	{
+		if (!$this->_element instanceof Constructed\Sequence) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_SEQUENCE));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a set type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a set
+	 *
+	 * @return \Sop\ASN1\Type\Constructed\Set
+	 */
+	public function asSet(): Constructed\Set
+	{
+		if (!$this->_element instanceof Constructed\Set) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_SET));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a numeric string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a numeric string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\NumericString
+	 */
+	public function asNumericString(): Primitive\NumericString
+	{
+		if (!$this->_element instanceof Primitive\NumericString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_NUMERIC_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a printable string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a printable
+	 *                                   string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\PrintableString
+	 */
+	public function asPrintableString(): Primitive\PrintableString
+	{
+		if (!$this->_element instanceof Primitive\PrintableString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_PRINTABLE_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a T61 string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a T61 string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\T61String
+	 */
+	public function asT61String(): Primitive\T61String
+	{
+		if (!$this->_element instanceof Primitive\T61String) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_T61_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a videotex string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a videotex string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\VideotexString
+	 */
+	public function asVideotexString(): Primitive\VideotexString
+	{
+		if (!$this->_element instanceof Primitive\VideotexString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_VIDEOTEX_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a IA5 string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a IA5 string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\IA5String
+	 */
+	public function asIA5String(): Primitive\IA5String
+	{
+		if (!$this->_element instanceof Primitive\IA5String) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_IA5_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as an UTC time type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a UTC time
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\UTCTime
+	 */
+	public function asUTCTime(): Primitive\UTCTime
+	{
+		if (!$this->_element instanceof Primitive\UTCTime) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_UTC_TIME));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a generalized time type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a generalized time
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\GeneralizedTime
+	 */
+	public function asGeneralizedTime(): Primitive\GeneralizedTime
+	{
+		if (!$this->_element instanceof Primitive\GeneralizedTime) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_GENERALIZED_TIME));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a graphic string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a graphic string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\GraphicString
+	 */
+	public function asGraphicString(): Primitive\GraphicString
+	{
+		if (!$this->_element instanceof Primitive\GraphicString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_GRAPHIC_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a visible string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a visible string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\VisibleString
+	 */
+	public function asVisibleString(): Primitive\VisibleString
+	{
+		if (!$this->_element instanceof Primitive\VisibleString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_VISIBLE_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a general string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not general string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\GeneralString
+	 */
+	public function asGeneralString(): Primitive\GeneralString
+	{
+		if (!$this->_element instanceof Primitive\GeneralString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_GENERAL_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a universal string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a universal string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\UniversalString
+	 */
+	public function asUniversalString(): Primitive\UniversalString
+	{
+		if (!$this->_element instanceof Primitive\UniversalString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_UNIVERSAL_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a character string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a character string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\CharacterString
+	 */
+	public function asCharacterString(): Primitive\CharacterString
+	{
+		if (!$this->_element instanceof Primitive\CharacterString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_CHARACTER_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a BMP string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a bmp string
+	 *
+	 * @return \Sop\ASN1\Type\Primitive\BMPString
+	 */
+	public function asBMPString(): Primitive\BMPString
+	{
+		if (!$this->_element instanceof Primitive\BMPString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_BMP_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as a constructed string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a constructed string
+	 *
+	 * @return \Sop\ASN1\Type\Constructed\ConstructedString
+	 */
+	public function asConstructedString(): Constructed\ConstructedString
+	{
+		if (!$this->_element instanceof Constructed\ConstructedString) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_CONSTRUCTED_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as any string type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a string
+	 *
+	 * @return StringType
+	 */
+	public function asString(): StringType
+	{
+		if (!$this->_element instanceof StringType) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_STRING));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * Get the wrapped element as any time type.
+	 *
+	 * @throws \UnexpectedValueException If the element is not a time
+	 *
+	 * @return TimeType
+	 */
+	public function asTime(): TimeType
+	{
+		if (!$this->_element instanceof TimeType) {
+			throw new \UnexpectedValueException(
+				$this->_generateExceptionMessage(Element::TYPE_TIME));
+		}
+		return $this->_element;
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function toDER(): string
+	{
+		return $this->_element->toDER();
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function typeClass(): int
+	{
+		return $this->_element->typeClass();
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function isConstructed(): bool
+	{
+		return $this->_element->isConstructed();
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function tag(): int
+	{
+		return $this->_element->tag();
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function isType(int $tag): bool
+	{
+		return $this->_element->isType($tag);
+	}
+
+	/**
+	 * {@inheritdoc}
+	 *
+	 * Consider using any of the `as*` accessor methods instead.
+	 */
+	public function expectType(int $tag): ElementBase
+	{
+		return $this->_element->expectType($tag);
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function isTagged(): bool
+	{
+		return $this->_element->isTagged();
+	}
+
+	/**
+	 * {@inheritdoc}
+	 *
+	 * Consider using `asTagged()` method instead and chaining
+	 * with `TaggedType::asExplicit()` or `TaggedType::asImplicit()`.
+	 */
+	public function expectTagged(?int $tag = null): TaggedType
+	{
+		return $this->_element->expectTagged($tag);
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function asElement(): Element
+	{
+		return $this->_element;
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function asUnspecified(): UnspecifiedType
+	{
+		return $this;
+	}
+
+	/**
+	 * Generate message for exceptions thrown by `as*` methods.
+	 *
+	 * @param int $tag Type tag of the expected element
+	 *
+	 * @return string
+	 */
+	private function _generateExceptionMessage(int $tag): string
+	{
+		return sprintf('%s expected, got %s.', Element::tagToName($tag),
+			$this->_typeDescriptorString());
+	}
+
+	/**
+	 * Get textual description of the wrapped element for debugging purposes.
+	 *
+	 * @return string
+	 */
+	private function _typeDescriptorString(): string
+	{
+		$type_cls = $this->_element->typeClass();
+		$tag = $this->_element->tag();
+		if (Identifier::CLASS_UNIVERSAL === $type_cls) {
+			return Element::tagToName($tag);
+		}
+		return Identifier::classToName($type_cls) . " TAG {$tag}";
+	}
 }