Towards a “write-only” repository…
By: John Hart
Tags: Cloud Services, AWS, Data Storage, Azure, Gcp

Just over a year ago and in a time when social interactions were much more frequent and much more personal I participated with members of my caving club on a trip to central Pennsylvania. The day was long and our adventure was a lot of fun (have you ever traveled down an underground river in a leaky aluminum row boat?). After our long day’s adventure, fatigue set in and the conversation waned on our ride home to the Philadelphia suburbs. As I gazed at the scenery sliding past our vehicle and as I became one with the soft red glow of the early evening, I mused about the concept of write-only storage and laughed out loud…

What the heck is a write-only repository?

Since the early days of computing, jokingly referring to a convoluted or poorly designed data store might be referred to as a “write-only” because finding or retrieving anything from it proved to be a painful or nearly impossible exercise (I’ve made this comment about more than one SharePoint installation). Typically the inability to find information in one of these repositories can be as much a matter of poor content organization as it is a matter of the design of the underlying storage technology.

From the ridiculous to (perhaps) the sublime

I occasionally enjoy taking seriously the apparently absurd. After my private chuckle on the car ride home and explaining to my companions that I wasn’t loosing my mind, I thought more deeply about the concept of a write-only repository through the eyes of a cloud architect. I asked myself, “Might there actually be use cases for a cloud-based write-only repository service?” My answer to this question was, “Yes”, with the principle use case being a situation where a user wants/needs to store sensitive information that they do not want to be able to access. The reasons that they would not to be able to access information stored in the service are: either they don’t want the information to be able to be discovered on their system (in their possession) or they do not want to be able to be forced/coerced into giving up the information that they have stored. Either of these motivations being self-protection (think, potential whistle-blowers).

Of course there’s a significant hitch with a write-only repository, since the information stored within the repository is completely inaccessible what value does it have? To overcome this hitch there needs to be at least one way to retrieve files from the service…

Subpoena only read-access

The value proposition of the service is that a file stored by the service is securely protected, difficult (but not impossible to access) and procedurally only able to be retrieved from the service for a governmental agency in response to a properly executed court order.

The White Cache…

I decided that creating a write-only repository cloud service was a possibility and thus the concept of the White Cache was born.

Each file uploaded by the service would have a lifespan after which it must be irretrievably deleted. The service would need to assign each file a unique key that could be used to pay to extend the lifespan of a file within the cache and that could be used to retrieve the file in response to a court order. The service would need to also obfuscate the “owner” of each file while simultaneously allowing the lifespan of the file to be extended one or more times. Security and access controls to the files within the repository and the repository itself would need to of the highest standard. Encryption in transit and at rest are required, as well as tight access controls on the storage and processing mechanisms.

To provide a degree of caching anonymity, a critical aspect of the service is to disassociate the payment process such that a the lifespan of a file is extended without creating a paper trail between the individual who paid for the storage. A final key feature is providing a zero-knowledge proof to assure users that their files still exist within the repository without the service actually being able to access the content of the files.

Because I built it, will they come?

Visit https://whitecache.com