Encryption in the cloud: who takes control?

Apologies for bastardising an already twee and somewhat dated saying, but there is more than a smidgeon of truth contained in "you don't have to encrypt your data in the cloud, but it sure helps" - if your corporate security posture is important to you. In other words, whilst encryption isn't the only answer to the cloud data security conundrum it is most certainly is one of the more important answers. Unfortunately, when it comes to questions the one nobody seems to be asking is just whose responsibility is the act of encrypting that data in the first place?