Security - Adobe Acrobat and PDF for Architecture, Engineering, and Construction - page 126

Certificate Security is more powerful than password security, and less likely to be easily broken.
Certificate Security is not password dependent, although you use a password associated with the digital
signature when applying it to a document.
A document can be certified or digitally signed by application of a digital signature which remains valid
unless the document is modified in ways other than those specified at the time of signing.

Table 10.1 Encryption options vary according to the compatibility version chosen

Change Permissions

Version/
Encryption
Level

Document
Components
Affected

Printing
Permissions

Other Permissions

Acrobat 3.0,
40-bit RC4

All contents None, high

resolution

Commenting, filling in form
fields, and signing existing
signature fields; page layout,
filling in form fields, and
signing existing signature
fields; any except extracting
pages

Enable copying of
text, images, and
other content and
access for the visually
impaired

Acrobat 5.0,
128-bit RC4

All contents None, low

resolution, high
resolution

Inserting, deleting, and
rotating pages; filling in form
fields and signing existing
signature fields; commenting,
filling in form fields, and
signing existing signature
fields; any except extracting
pages

Enable copying of
text, images, and
other content; enable
text access for screen
reader devices for the
visually impaired

Acrobat 6.0,
128-bit RC4

All contents;
all document
contents
except
metadata

None, low
resolution, high
resolution

Inserting, deleting, and
rotating pages; filling in form
fields and signing existing
signature fields; commenting,
filling in form fields, and
signing existing signature
fields; any except extracting
pages

Enable copying of
text, images, and
other content; enable
text access for screen
reader devices for the
visually impaired

Acrobat 7.0,
128-bit AES

All contents;
all document
contents
except
metadata;
only file
attachments

None, low
resolution, high
resolution

Inserting, deleting, and
rotating pages; filling in form
fields and signing existing
signature fields; commenting,
filling in form fields, and
signing existing signature
fields; any except extracting
pages

Enable copying of
text, images, and
other content; enable
text access for screen
reader devices for the
visually impaired

Creating a Digital Signature

Acrobat contains two complementary processes called certifying and signing . The difference between the
two lies in their application. The document's originator can either certify or sign a document; subsequent
digital IDs can be applied as signatures only.