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Adobe Acrobat SDK
Adobe® Supplement to the ISO 32000
3.5.4 Crypt Filters
Modify Table 3.22 where only changed entries are shown. Unchanged content is shown in gray.
KEY
CFM
Length
TABLE 3.22 Entries common to all crypt filter dictionaries
TYPE
VALUE
name
(Optional) The method used, if any, by the consumer application to
decrypt data. The following values are supported:
None
stream to the security handler for decryption. (See implementation
note 30 in Appendix H.)
The application asks the security handler for the encryption key
V2
and implicitly decrypts data with Algorithm 3.1, using the RC4
algorithm.
AESV2
encryption key and implicitly decrypts data with Algorithm 3.1, using
the
mode
randomly generated and placed as the first 16 bytes in the stream or
string.
AESV3
for the encryption key and implicitly decrypts data with
Algorithm 3.1a, using the AES-256 algorithm in Cipher Block
Chaining (CBC) with padding mode with a 16-byte block size and an
initialization vector that is randomly generated and placed as the
first 16 bytes in the stream or string. The key size (Length) shall be
256 bits.
When the value is V2,
this encryption key and cache the key for subsequent use for streams
that use the same crypt filter. Therefore, there must be a one-to-one
relationship between a crypt filter name and the corresponding
encryption key.
Only the values listed here are supported. Applications that encounter
other values should report that the file is encrypted with an
unsupported algorithm.
Default value:
integer
(Required if the value for the V key in Table 3.18 is 2 or 3, optional otherwise)
The bit length of the encryption key. It must be a multiple of 8 in the
range of 40 to
Note:
Security handlers can define their own use of the
but are encouraged to use it to define the bit length of the
encryption key.
The application does not decrypt data but directs the input
(PDF 1.6) The application asks the security handler for the
AES-128
algorithm in Cipher Block Chaining (CBC)
with a 16-byte block size and an initialization vector that is
The key size (
Length
(ExtensionLevel 3) The application asks the security handler
AESV2, or AESV3,
.
None
128 256.
Syntax (Chapter 3 in PDF Reference)
3.5.4 Crypt Filters
) shall be 128 bits.
the application may ask once for
22
with padding
entry
Length
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