What algorithm does Microsoft Office 2010 use for encryption?

encryption cryptography ms-office powerpoint
user478636 picture user478636 · Mar 31, 2011 · Viewed 11.4k times · Source

Does it use the standard AES 128bit key for encryption? I've searched a lot on Google, but I still haven't found the algorithm is uses for encrypting.

I'm encrypting a PowerPoint file.

Answer

Luke picture Luke · Mar 31, 2011

This technet article confirms that the defaults are AES 128-bit key, SHA1, CBC.

Although there are Office 2010 settings to change how encryption is performed, when you encrypt Open XML Format files (.docx, .xslx, .pptx, and so on) the default values — AES (Advanced Encryption Standard), 128-bit key length, SHA1, and CBC (cipher block chaining) — provide strong encryption and should be fine for most organizations.

It is important to note, however, that encryption is export controlled and that all versions of windows may not have all cryptographic providers installed. The article also mentions that you can see which Cryptographic Service Providers are installed by checking the registry key:

HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Cryptography/Defaults/Provider

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