• Christopher Williamson

What is PAD - And why are we building it?




What is PAD?


Technologists are collectively building a new internet: a Web 3.0 that emphasises decentralised trust and radical transparency. We share that vision. Our contribution to it is a trustlessly transparent information escrow.


We call it PAD.


There are many scenarios in which you may wish to provide someone else with conditional access to information. You may feel safer if your location was shared with a loved one - but you would prefer that information only be accessed in an emergency.


Unfortunately, it is not simple to set up a conditional information escrow. Directly providing the information to the recipient requires trust that they will not use the data prior to the appropriate time. Any plan to send data only after the specified conditions are met assumes that you will still have it in storage and be able to send it. Asking a third party to store the data introduces a single point of failure and leaves the judgment of whether to release the information to this trusted party.


PAD enables conditional access to information without trusted third parties or single points of failure. There is now a middle ground between sharing data or not sharing it: you can share the capability to access information. Along with this privilege comes a cryptographically-backed transparency guarantee: you will always know whether and when the data is accessed and there is no way for any party to avoid accountability.



PAD provides:

  • A secure and highly available data store that allows a designated recipient to access information regardless of circumstances at any time in the future, without trusted third parties, master keys, or reliance on non-cryptographic operations-based security.

  • A guarantee that data remains private and encrypted until the point that the information is requested by a designated recipient.

  • Cryptographically-enforced transparency about who decrypts and accesses data and when, so that anyone who inappropriately uses data can be held accountable and be exposed to judicial or regulatory challenge.


We believe that the PAD protocol and its model of information sharing is important. Too often in today’s interactions, we overshare data by providing it unconditionally, or undershare by not providing it at all. With PAD, these interactions and sharing arrangements can be customised and conditional. Moreover, the logic dictating when data can be appropriately accessed is almost always impossible to encode programmatically due to the complexity of life. PAD embraces this complexity by leaving the decision to decrypt to humans rather than machines.


The philosophy of PAD is to leave the human decisions to people - and to use technology to enforce transparency.



How does PAD work?


Imagine that you have some sensitive information that you want to share with a ‘guardian’ George under certain conditions. With the PAD system, you encrypt that data and provide George with the ciphertext or store it on a ledger for greater durability using our API. George has no ability to decrypt the ciphertext himself; the encryption is done using a special kind of key. Ciphertexts created with this key can only be decrypted by a threshold number of distributed parties that we call trustees.


When George wishes to access the information, he must post a request on an immutable, append-only blockchain-secured ledger. Trustees monitor this ledger for data requests and once they verify the source of the request, they jointly perform a decryption that allows George to access your information.

PAD is carefully designed so that there is no way for George to access the data without posting his request on the blockchain. This guarantees transparency of whether and when he has made his request. The decryption service is always available, as long as a threshold number of trustees are performing their service. If George submits his request at an inappropriate time, then you have irrefutable evidence of this and can take appropriate action.


Anyone can become a PAD trustee, and everyone can choose which trustees they want to rely on. The team is currently recruiting trustees from cryptography and privacy groups at esteemed universities.



Applications of PAD



PAD Places



Your location can reveal much private information: where you live and work, who your friends are, and even whether you are travelling or at home. But still, there are times when you wish to share your whereabouts. You call your friend to inform her of which restaurant you are taking your new date or to which mountain you are climbing this weekend. Location sharing is an unavoidable fact of life. But sensibly, we should only share our location under certain circumstances.


Solutions for location tracking are generally all-or-nothing: you opt not to share your location, or you let your phone track where you are and it shares this information with a nominated person. We think there’s a better way to manage this challenge with PAD. That’s why we are building a location sharing app that lets you nominate those you trust with the privilege to access your current location. Because this app is built with PAD, you always enjoy full transparency over who has exercised that privilege and made a request; if you discover that one of your contacts is abusing your trust and decrypting your location more often than is justified, then you can remove their access.


PAD Places is available on both the App Store and Google Play.



PAD Recovery



Digital asset ownership is entering the mainstream. This is a strong motivation to build more robust and easily understood seed phrase and private key recovery tools. A common practice for seed phrase storage is to write it down by hand and store this in a secure location. A more secure alternative is to engrave the phrase on a metal plate. Problematically, both methods introduce a single point of failure. Smart contract wallets of the type proposed by Vitalik Buterin avoid seed phrases, but still require that wallet ‘guardians’ are able to store or recover their own private keys. Social recovery wallets exist that break your seed phrase into pieces and store those pieces with associates that you trust - but these solutions lock you into a single choice of wallet and do not provide full cryptographically-backed transparency of what those associates are oing with your seed phrase piece.


We are using PAD to build a general purpose mechanism for storage and recovery of any kind of sensitive information. The idea is simple. You encrypt your data using the special key held by the PAD trustees and nominate a set of trusted guardians who hold the ciphertext and who are required to approve any decryption done by PAD trustees. When you have lost your information, you ask your guardians to request decryption through the PAD system. Your guardians verify your identity and once a threshold number of them have done so, PAD trustees perform a decryption that allows you (and only you) to recover your data. It matters not what this data is, so there is no technology lock-in. The transparency of PAD means that you retain full visibility over which guardians have made a request - or which have failed to.


Finally, in the remote chance that your guardians collude to request decryption without authorisation, you have visibility of this and a PAD-enforced delay provides you with the opportunity to move your assets to a safe wallet before your phrase or keys are revealed.


If you would like to keep up to date with the PAD team and the development of PAD Recovery, follow us on our social media channels:


Twitter: @PADtech_team

LinkedIn: PAD Tech