Vawlt Origins — Part I

During the next few stories, we are happy to share with you the beginnings of Vawlt. We must warn you, though, it’s gonna get a bit technical.

For us, things started getting serious with this paper: DEPSKY. Led by our CTO — Alysson Bessani — this publication presents “a system that improves the availability, integrity and confidentiality of information stored in the cloud through the encryption, encoding and replication of the data on diverse clouds that form a cloud-of-clouds.”. Such a system overcomes the limitations of individual clouds by using an efficient set of Byzantine quorum system protocols, cryptography, secret sharing, erasure codes and the diversity that comes from using several clouds.

This virtual cloud storage system tackled 4 important limitations of cloud computing for data storage:

  • loss of availability — DEPSKY deals with this problem by exploiting replication and diversity to store the data on several clouds, thus allowing access to the data as long as a subset of them is reachable;
  • loss and corruption of data — DEPSKY deals with this problem by using Byzantine fault-tolerant replication to store data on several cloud services, allowing data to be retrieved correctly even if some of the clouds corrupt or lose data;
  • loss of privacy — DEPSKY employs a secret sharing scheme and erasure codes to avoid storing clear data in the clouds and to improve the storage efficiency, amortizing the replication factor on the cost of the solution;
  • vendor lock-in — DEPSKY addresses this issue in two ways. First, it does not depend on a single cloud provider, but on a few, so data access can be balanced among the providers considering their practices. Second, DEPSKY uses erasure codes to store only a fraction (typically half) of the total amount of data in each cloud. In case the need of exchanging one provider by another arises, the cost of migrating the data will be at most a fraction of what it would be otherwise.

The apparent set back of this value proposition is that we are using, at least, 4 clouds instead of 1, so one would expect the storage costs to go up to four times the cost of a single cloud. This was of the key objectives of DEPSKY, that managed to reduce such costs to about 2 times the cost of a single cloud, and these are the technical reasons driving Vawlt’s pricing model.

If you want to dig deeper into our system, we invite to read the whole document and throw us your comments and questions.

You can also wait for our next stories that will report the evolution of DEPSKY into Vawlt.

Vawlt Team