Digital Identity, Trust and Privacy on the open Internet

Blockchains: Evidence of Mediated Computation

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In writing of the report of the Kantara BSC group (Blockchain and Smart Contracts) – a group that has been meeting bi-weekly for the past 7 months – we have come across numerous use-cases proposed by members who are looking closely at blockchain technology (or more generally from distributed ledger technology).

To enable classification of these use-cases,  some criteria were agree upon that  would highlight the features of blockchain systems. Since the attraction of blockchain technology (and more generally of distributed ledgers) lies in its empowering parties to transact without the need for a single (or few) intermediary, the following criteria has helped the team classify the received use-cases:

  • Individuals controlling their own data: Does the use-case seek to empower individuals to begin with, and does blockchain technology help to achieve that goal.
  • Individuals rising to the level of a “peer” in transactions with others: Does the use-case require individuals to function at a peer-level (or can the same outcome be achieved using other paradigms), and does blockchain technology help to achieve that goal.
  • Evidence of mediated computation: Does the use-case require immutable evidence that a neutral third party (e.g. some computer, somewhere) mediated the transaction, without which the transaction outcome would be worthless to the transacting parties.

The last criterion points to a feature of blockchain technology that is often overlooked. In many discourses regarding applications of blockchain technology, authors assume (forget) that the blockchain system consists of a network of peer-to-peer nodes which perform some computation (e.g. proof or work mining) towards the completion of a transaction. As such, one or more of these nodes are in fact performing mediated computation (to some degree) and at the same time provide evidence of this mediated act.

If evidence of mediated computation is crucial to the acceptance of a transaction, it implies that stronger forms of technical-trust must be produced by the entity (i.e. node; server; device) that is performing the computation. New forms of remote attestation may need to be devised, something along the lines of the SGX architecture that provide evidence that a given computation was performed within a secure enclave.

This raises another prospect: different nodes on a blockchain system may offer different levels of trustworthy computation, each with an associated cost (i.e. tiers of trusted computation services on the P2P network).




Written by thomas

April 2nd, 2017 at 2:56 pm