Adobe 12020596 User Guide - Page 14

TABLE 3.18 Entries common to all encryption dictionaries, DESCRIPTION

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Adobe Acrobat SDK Adobe® Supplement to the ISO 32000 Syntax (Chapter 3 in PDF Reference) 3.5 Encryption 14 Modify Table 3.18 as shown below where only entries that changed are listed in the table. The V entry has a new value of 5; the only change to the other listed entries (StmF, StrF, and EFF) is to qualify them for use when V is 5. Unchanged text is shown in gray. TABLE 3.18 Entries common to all encryption dictionaries KEY TYPE DESCRIPTION V number (Optional but strongly recommended) A code specifying the algorithm to be used in encrypting and decrypting the document: 0, An algorithm that is undocumented and no longer supported, and whose use is strongly discouraged. Old files may use this value but no new files should be written using 0. 1, Algorithm 3.1 on page 119, with an encryption key length of 40 bits; see below. 2, (PDF 1.4) Algorithm 3.1, but permitting encryption key lengths greater than 40 bits. 3, (PDF 1.4) An unpublished algorithm that permits encryption key lengths ranging from 40 to 128 bits; see implementation note 22 in Appendix H. 4, (PDF 1.5) The security handler defines the use of encryption and decryption in the document, using the rules specified by the CF, StmF, and StrF entries using algorithm 3.1 with a key length of 128 bits. 5, (ExtensionLevel 3) The security handler defines the use of encryption and decryption in the document, using the rules specified by the CF, StmF, and StrF entries using algorithm 3.1a with a key length of 256 bits. The default value if this entry is omitted is 0, but a value of 1 or greater is strongly recommended. (See implementation note 23 in Appendix H.) StmF name (Optional; meaningful only when the value of V is 4, or 5 for ExtensionLevel 3) The name of the crypt filter that is used by default when decrypting streams. The name must be a key in the CF dictionary or a standard crypt filter name specified in Table 3.23. All streams in the document, except for cross-reference streams (see Section 3.4.7, "Cross-Reference Streams") or streams that have a Crypt entry in their Filter array (see Table 3.5), are decrypted by the security handler, using this crypt filter. Default value: Identity.

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Adobe Acrobat SDK
Syntax (Chapter 3 in PDF Reference)
Adobe® Supplement to the ISO 32000
3.5 Encryption
14
Modify Table 3.18 as shown below where only entries that changed are listed in the table. The
V
entry has a new
value of 5; the only change to the other listed entries (
StmF
,
StrF
, and
EFF
) is to qualify them for use when
V
is
5
. Unchanged text is shown in gray.
TABLE 3.18 Entries common to all encryption dictionaries
KEY
TYPE
DESCRIPTION
V
number
(
Optional but strongly recommended
) A code specifying the algorithm to
be used in encrypting and decrypting the document:
0
, An algorithm that is undocumented and no longer supported, and
whose use is strongly discouraged.
Old files may use this value but
no new files should be written using 0.
1
, Algorithm 3.1 on page 119, with an encryption key length of 40
bits; see below.
2
, (PDF 1.4) Algorithm 3.1, but permitting encryption key lengths
greater than 40 bits.
3
, (PDF 1.4) An unpublished algorithm that permits encryption key
lengths ranging from 40 to 128 bits; see implementation note 22 in
Appendix H.
4
, (PDF 1.5) The security handler defines the use of encryption and
decryption in the document, using the rules specified by the
CF
,
StmF
, and
StrF
entries
using algorithm 3.1 with a
key length of 128
bits.
5, (
ExtensionLevel 3
) The security handler defines the use of
encryption and decryption in the document, using the rules
specified by the
CF
,
StmF
, and
StrF
entries using algorithm 3.1a
with a
key length of 256 bits.
The default value if this entry is omitted is 0, but a value of 1 or greater is
strongly recommended.
(See implementation note 23 in Appendix H.)
StmF
name
(
Optional; meaningful only when the value of
V
is
4
,
or 5 for
ExtensionLevel 3
) The name of the crypt filter that is used by default
when decrypting streams. The name must be a key in the
CF
dictionary
or a standard crypt filter name specified in Table 3.23. All streams in the
document, except for cross-reference streams (see Section 3.4.7,
“Cross-Reference Streams”) or streams that have a
Crypt
entry in their
Filter
array (see Table 3.5), are decrypted by the security handler,
using this crypt filter.
Default value: Identity.