Can't open modify password protected presentation in Viewer
You try to open a presentation in PowerPoint Viewer 2003 and it asks for a password and won't allow you to view the presentation (even if you happen to know the password)
This is normal for presentations that are protected against opening, but if the presentation is protected against modification only, it should open without prompting for a password in the Viewer. In PowerPoint itself, you should be prompted for a password or given the chance to open the presentation as Read-Only.
However, depending on the type of encryption applied to the presentation and your Windows version, you may not be able to open the presentation.
For example, if the presentation is protected with RC4, Microsoft Enhanced DSS and Diffie-Hellman
Cryptographic Provider with a key size of 128, it won't open under Windows 98SE. Even if you know the password, when you enter it, you see an Incorrect Password message and the presentation won't open.
The same presentation opens without prompting for a password if it's encrypted with a key size of 40 using:
- RC4, Microsoft Base Cryptographic Provider v1.0 or
- RC4, Microsoft base DSS and Diffie-Hellman Cryptographic Provider
In order to open the presentation, you'll need to ask the person who created it to resave with a different encryption setting and send it to you again.
When assigning a password in PowerPoint 2002 or 2003, the author of the presentation should go to File, Save As, Tools, Security Options and click on the Advanced button to ensure that one of the above encryption methods is selected. Then assign a password.
As always, a cordial thanks to Enric Maņas [MS MVP Office-PowerPoint] for his thorough investigations.