Whereas the "cloud computing" is an economic and ecological tool to improve the computing performance of public and private companies, reduce processing costs and limit storage costs, which has many advantages, but also suffers from insecurity the connection between the user and the server, and some loss of control by the user.
The "cloud computing" allows access to a shared computing resources that can be relayed quickly with minimal management effort pole and minimal interaction from the service provider, and that the effectiveness of the "cloud" is in its flexibility, increased productivity brings and its role in preserving the environment, but above all must be technically reliable and robust so that the implementation of digital signature services and innovative solutions must be done according to the best IT security standards.
Therefore, if exists in Europe or North America digital signature deployments in the cloud, would be good to know about it.
There are many vendor who provide digital signature as a service (e.g. Ascertia) or provide an API to use with cloud applications (e.g. DocuSign). However, the problem with such approaches is that you have to trust the cloud with your private signing key as you have to hand over the key to do the signing. I wonder if there are any research projects that look into the possibility of performing oblivious signing in the cloud (this is different from blind signatures).
You can catch a glimpse of a Swedish publication about PKI as a Service at https://www.nada.kth.se/utbildning/grukth/exjobb/rapportlistor/2011/rapporter11/wanggren_joakim_11025.pdf
Cloud security is an open umbrella that covers very large set of issues. Lot of progress was made in Cryptography and PKI technologies to secure cloud. I would aslo recommend reading: Cloud Security Alliance. Security Guidance for Critical Areas of Focus in Cloud Computing V2.1. CSA Report, 2011.
Thanks Mohamed, aproach in spanish http://www.pcworldenespanol.com/2012/05/04/las-firmas-digitales-son-la-mejor-opcion-2/
Thanks Gunter, very usefull and interesting paper!
Thanks a lot Eduard, it's the guidance tha I'll reference to this work!