protected static function _decodeFromDER(Identifier $identifier, $data, &$offset)
{
$idx = $offset;
if (!$identifier->isPrimitive()) {
throw new DecodeException("Null value must be primitive.");
}
// null type has always zero length
Length::expectFromDER($data, $idx, 0);
$offset = $idx;
return new self();
}
/**
*
* @see \ASN1\Type\Tagged\ImplicitTagging::implicit()
* @return UnspecifiedType
*/
public function implicit($tag, $class = Identifier::CLASS_UNIVERSAL)
{
$identifier = $this->_identifier->withClass($class)->withTag($tag);
$cls = self::_determineImplClass($identifier);
$idx = $this->_offset;
$element = $cls::_decodeFromDER($identifier, $this->_data, $idx);
return new UnspecifiedType($element);
}
/**
*
* @see \ASN1\Type\Tagged\ImplicitTagging::implicit()
* @return UnspecifiedType
*/
public function implicit($tag, $class = Identifier::CLASS_UNIVERSAL)
{
$this->_element->expectType($tag);
if ($this->_element->typeClass() != $class) {
throw new \UnexpectedValueException("Type class " . Identifier::classToName($class) . " expected, got " . Identifier::classToName($this->_element->typeClass()) . ".");
}
return new UnspecifiedType($this->_element);
}
/**
*
* @see \ASN1\Element::_decodeFromDER()
* @return self
*/
protected static function _decodeFromDER(Identifier $identifier, $data, &$offset)
{
$idx = $offset;
if (!$identifier->isPrimitive()) {
throw new DecodeException("DER encoded string must be primitive.");
}
$length = Length::expectFromDER($data, $idx);
$str = $length->length() ? substr($data, $idx, $length->length()) : "";
// substr should never return false, since length is
// checked by Length::expectFromDER.
assert('is_string($str)', "substr");
$offset = $idx + $length->length();
try {
return new static($str);
} catch (\InvalidArgumentException $e) {
throw new DecodeException($e->getMessage(), null, $e);
}
}
/**
* Get textual description of the wrapped element for debugging purposes.
*
* @return string
*/
private function _typeDescriptorString()
{
$type_cls = $this->_element->typeClass();
$tag = $this->_element->tag();
if ($type_cls == Identifier::CLASS_UNIVERSAL) {
return Element::tagToName($tag);
}
return Identifier::classToName($type_cls) . " TAG {$tag}";
}
/**
* Get textual description of the type for debugging purposes.
*
* @return string
*/
protected function _typeDescriptorString()
{
if ($this->typeClass() == Identifier::CLASS_UNIVERSAL) {
return self::tagToName($this->_typeTag);
}
return Identifier::classToName($this->typeClass()) . " TAG " . $this->_typeTag;
}
/**
*
* @see \ASN1\Element::isConstructed()
* @return bool
*/
public function isConstructed()
{
return $this->_identifier->isConstructed();
}
/**
* Explode DER structure to DER encoded components that it contains.
*
* @param string $data
* @throws DecodeException
* @return string[]
*/
public static function explodeDER($data)
{
$offset = 0;
$identifier = Identifier::fromDER($data, $offset);
if (!$identifier->isConstructed()) {
throw new DecodeException("Element is not constructed.");
}
$length = Length::expectFromDER($data, $offset);
$end = $offset + $length->length();
$parts = array();
while ($offset < $end) {
// start of the element
$idx = $offset;
// skip identifier
Identifier::fromDER($data, $offset);
// decode element length
$length = Length::expectFromDER($data, $offset);
// extract der encoding of the element
$parts[] = substr($data, $idx, $offset - $idx + $length->length());
// update offset over content
$offset += $length->length();
}
return $parts;
}
