Key |
Type |
Value |
---|---|---|
Type |
name |
(Optional) If present, shall be CryptFilter for a crypt filter dictionary. |
CFM |
name |
(Optional) The method used, if any, by the conforming reader to decrypt data. The following values shall be supported: NoneThe application shall not decrypt data but shall direct the input stream to the security handler for decryption. V2The 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. |
AuthEvent |
name |
(Optional) The event to be used to trigger the authorization that is required to access encryption keys used by this filter. If authorization fails, the event shall fail. Valid values shall be: DocOpen: Authorization shall be required when a document is opened. EFOpen:Authorization shall be required when accessing embedded files. Default value: DocOpen. If this filter is used as the value of StrF or StmF in the encryption dictionary (see Table 20 ), the conforming reader shall ignore this key and behave as if the value is DocOpen. |
Length |
integer |
(Optional) The bit length of the encryption key. It shall be a multiple of 8 in the range of 40 to 128. Security handlers may define their own use of the Length entry and should use it to define the bit length of the encryption key. Standard security handler expresses the length in multiples of 8 (16 means 128) and public-key security handler expresses it as is (128 means 128). |