[Discuss] Discuss Digest, Vol 6, Issue 9

[odonovan at hkl.hms.harvard.edu (Dan O'Donovan)]

On Nov 4, 2011, at 2:14 PM, Hsuan-Yeh Chang wrote:

> 1. Is there a way to encrypt data stored with cloud services (such as
> dropbox) that can be decrypted only by the data owner, not by "agent"?
> I believe PGP can do a pretty good job, am I correct?

Sure it can, but one of the reasons that DropBox is great is because it saves incremental backups of your files (tracking changes and the like). If you start encrypting them you loose this - also, if you're encrypting an image of some kind (so you don't have to enter a passkey every time you access the file - ie unencrypting a file at a time) then you'll have massive changes to upload every time you access files. So yes - but it's probably not workable (yet - maybe a good business idea)

> 2. If I send an e-mail (with attachment) from Gmail to Hotmail, would
> both Google and Microsoft keep this e-mail on their respective servers
> forever?

Probably - at least they would reserve the right to

> Wouldn't that quickly explode the service provider's storage space?

Disk space is cheap - 'cloud storage' anyone?

> Would the ISP also keep a copy of that e-mail?

Gmail (at least) uses (correct me everyone) SSL transport encryption when it can so hopefully your ISP won't know whats in there - I wouldn't bet on it though

Dan (with tinfoil hat on) O'Donovan