Office 2010 Encryption Setting: AES-256 or Default?

[TJCS]

I always thought Office 2010 and Office 2007 both uses the same default cryptographic service provider: Microsoft Enhanced RSA and AES Cryptographic Provider, AES-128, 128-bit. But what Microsoft states here seems to hint that Office 2010 uses a more advance encryption format than Office 2007:

It is important to realize that, when you set CompatMode to 0(required to change encryption to AES-256), Office 2010 uses an Office 2007 compatible encryption format, instead of the enhanced security that is provided by default when you use Office 2010 to encrypt Open XML Format files.

I currently have Excel 2010 set to use Microsoft Enhanced RSA and AES Cryptographic Provider, AES-256, 256-bit. And I want to know if this is the most secure encryption algorithm available for Office 2010 or should i leave the Office 2010 encryption at default(or some other algorithm...)?

 

[Chiefcrowe]

256 bit should be more than enough really. I do believe it is unbreakable right now.

 

[TJCS]

I Agree. After actually figuring out how to increase Office 2010 Encryption to AES-256, I told a friend of mine that I can do it for all his computers at his company, but now I am not so sure if it is worth the hassle.

 

[TJCS]

There seems to be very little documentation in the "enhanced security" in office 2010, but I found this security firm's blog interesting:

In Office 2007, ECMA-376 with SHA-1 hash and AES-128 encryption is implemented. The number of hash rounds is 50000 that makes password recovery really difficult and slow. Office 2010 also uses SHA-1 and AES-128, but the number of hash rounds is now 100000. Therefore password recovery for new Office files will be two times slower.
- Source

 

[TJCS]

My bad, there is actually a page that has an overview of the security enhancement in office 2010 found here.

 

[TJCS]

I have only been able to set Office 2010 to AES-256 Encryption by running in Office 2007 compatibility format, if anyone know how to do it without using the Office 2007 format please let me know thanks.