class final Core · roukmoute/pdf 0.6.2
PDF\Specification\Dictionary\CryptFilterDictionaryTable25\CFMEntryTable 25, /CFM; PDF type: name; Optional.Inheritance and contracts
Parent : PDF\Specification\SchemaEntry
Definition in the specification
Table 25 · Entries common to all crypt filter dictionaries
ISO 32000-1:2008, §7.6.5 · PDF page 76 ↗
/CFM name
(Optional) The method used, if any, by the conforming reader to decrypt data. The following values shall be supported: None The application shall not decrypt data but shall direct the input stream to the security handler for decryption. V2 The application shall ask the security handler for the encryption key and shall implicitly decrypt data with "Algorithm 1: Encryption of data using the RC4 or AES algorithms", using the RC4 algorithm. AESV2 (PDF 1.6) The application shall ask the security handler for the encryption key and shall implicitly decrypt data with "Algorithm 1: Encryption of data using the RC4 or AES algorithms", using the AES algorithm in Cipher Block Chaining (CBC) mode with a 16-byte block size and an initialization vector that shall be randomly generated and placed as the first 16 bytes in the stream or string. When the value is V2 or AESV2, the application may ask once for this encryption key and cache the key for subsequent use for streams that use the same crypt filter. Therefore, there shall be a one-to-one relationship between a crypt filter name and the corresponding encryption key. Only the values listed here shall be supported. Applications that encounter other values shall report that the file is encrypted with an unsupported algorithm. Default value: None.
Qualifier: Optional
Conditional descriptions remain traceable. A definition alone does not implement a codec, a signature or every format mechanism. Read the coverage.
Construction
__construct()
public function __construct(PDF\Syntax\Object\NameType|PDF\Syntax\Object\IndirectReference $value)Inherited methods
3 methods from parents and contracts
definition()
public function definition(): PDF\Specification\EntryDefinitionkey()
public function key(): PDF\Syntax\Object\NameTypevalue()
public function value(): PDF\Syntax\FileStructure\BasicTypeProperties
| Declaration | Origin and documentation |
|---|---|
public readonly PDF\Syntax\Object\NameType $key | PDF\Syntax\Object\DictionaryObject\Entry |
public readonly PDF\Syntax\FileStructure\BasicType $value | PDF\Syntax\Object\DictionaryObject\Entry |
Constants
| Name | PHP value | Origin |
|---|---|---|
KEY | | PDF\Specification\Dictionary\CryptFilterDictionaryTable25\CFMEntry |
TABLE | | PDF\Specification\Dictionary\CryptFilterDictionaryTable25\CFMEntry |
VARIABLE | | PDF\Specification\SchemaEntry |