Microsoft Office Tutorials and References
In Depth Information
Unsupported Features
Change — To allow users to edit and save the workbook, grant them Write permissions to the
document library or folder.
Copy and Print — Copy and print permissions cannot be separated from the read access. Users
who have only the View Item permissions can view the workbook in the browser, and copy and
print the displayed range using the browser’s copy and print functionality. Users who also have
the Open Item right can open the workbook in Excel and use Excel’s copy and print features.
Programmatic access — You can restrict this by changing permissions on the API web service of
the WFE.
You can also define Information Rights Management settings for document libraries on the SharePoint
server. Excel Services does not allow users to open workbooks from these document libraries.
Digital Signatures
A digital signature identifies the originating author of a workbook, and signifies that the workbook has
not been altered since it was signed.
To set up a digital signature in Excel, click the Office button, click Prepare, select Add a Digital Signature,
and follow the instructions in the dialog box. Creating a digital signature marks the workbook as final and
read-only, so no additional changes can be done on the workbook.
Excel Services does not support opening workbooks with digital signatures set on them. As long as the
users open the workbooks on the server by using the EWA, the SharePoint security model is a good
substitute for digital signatures. The administrator of the server should set up security in such a way as to
limit who has permissions to upload files to the document library, and use the SharePoint auditing
feature to keep track of who has changed a document. In addition, it is expected that the end user trusts the
server and its administrator.
When you download the file from the server to the client, and then share it with other users, there is no
digital signature to validate and authenticate the source of the workbook.
Document Encryption
You can use document encryption to specify a password that is required to open a document. These
documents are encrypted using an encryption algorithm that you can specify when saving the file. Users
opening the file will be prompted to enter the password before being allowed to see the document.
Depending on the strength of the encryption algorithm that you are using, it might be difficult for
malicious users to break the encryption, but it might still be possible to do it using a brute-force attack.
To set up encryption in Excel, click the Office button, click Prepare, select Encrypt Document, and fill in
the password.
Excel Services does not support opening encrypted workbooks. Instead, you should use the SharePoint
security model to specify which users have permissions to the workbook. Users who have View Item
rights are allowed to view the workbook in EWA, but cannot download it to the client. Users who also
have the Open Item right can download the file and view it in the client.
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