Blockchain, Digital Signatures and Identity

It seems anytime I talk to people about the last few years of my professional life, they ask me about how I see traditional X.509 based Public Key Infrastructure and Blockchain technologies intersecting in the future. I think the most obvious intersection between these two technologies is related to contracts.

When cryptography is used for electronic signatures, X.509 certificates are at the core of how signatures are applied. Today there are numerous startups looking at how to squeeze bitcoin into future solutions in this area:

RFC3161 Timestamping Proof Of Existence and Bit Proof
PAdES PDF Signatures BlockSign
X.509 Certificates OneName, World Citizenship, NameCoin, NetKi, etc.

In the United States these alternate Blockchain approaches do not have any regulatory barriers to acceptance, but outside the U.S. they don’t really have much of a chance since most countries specify which specific technologies and processes must be used to qualify as a legal signature.

As such I generally look at these products (at least in the frame of contracts) as solutions looking for problems. The core issue being that they offer limited, if any, material benefit over the existing technological approaches which have both a history and legal framework to support them.

This is particularly a large issue when you consider how global commerce has become, and that each jurisdiction has very different ideas of what constitutes a valid digital signature and contract.

With that said, I am a big believer in the idea of Smart Contracts and do see value in Proof of Existence, but they are features in broader solutions and not products in unto themselves.

But what about the blockchain and Identity Management? When looking at this we first have to remember that at its core Bitcoin is a public ledger — a public repository. The only identity related problem that requires a public repository is discovery of information, more specifically discovery of information that can not be easily discovered in context.

A great example of this is a Bitcoin wallet address. It is both impractical and unreasonable to expect users to pass these values around without error, which is why most of the identity solutions built on Blockchain technology focus on this problem. This is not so different from the problem of discovery of S/MIME or PGP certificates for encrypted mail.

The reality is that one does not need the blockchain to solve this problem, in-fact Facebook recently announced that they are now letting you publish your PGP key on your profile. There is nothing stopping them or any of the other public directory services users already use from publishing other similar values.

I would even go so far to argue the use of Bitcoin given the size of the Blockchain is a liability in these scenarios. Today the Blockchain is over 30GB in size and with over 60% of internet usage being mobile this means (at least for peer to peer cases) one would need to rely on something like Simple Payment Verification (SPV) for mobile devices, which inherently places some trust on a node anyway.

The Bitcoin purist would argue that any use of a trusted third-party is an apples-to-oranges comparison. Here is the kicker though — when it comes to bootstrapping trust you have to trust something/someone and this is especially true when it comes to verifying a legal identity. The net of which is since you have to trust a centralized repository, you do not strictly need a Blockchain based approach.

Long term I see us moving to a model where the federated concept of identity we use with consumer services today is extended to government and business services. We already see this happening with service offerings and the recent work in the EU around eIDAS and the US with NSTIC it seems that this trend won’t be slowing anytime soon.

If that is true then, these Blockchain based identity solutions will either pivot into new solutions or their future will be inextricably tied to the Bitcoin wallet address discovery problem.

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