Group items tagged

A broad statement of the key idea of smart contracts, then, is to say that contracts should be embedded in the world.

And where the vending machine, like electronic mail, implements an asynchronous protocol between the vending company and the customer, some smart contracts entail multiple synchronous steps between two or more parties

POS (Point of Sale)

EDI (Electronic Data Interchange

SWIFT

allocation of public network bandwidth via automated auctions

Smart contracts reference that property in a dynamic, proactively enforced form, and provide much better observation and verification where proactive measures must fall short.

The mechanisms of the world should be structured in such a way as to make the contracts (a) robust against naive vandalism, and (b) robust against sophisticated, incentive compatible (rational) breach.

A third category, (c) sophisticated vandalism (where the vandals can and are willing to sacrifice substantial resources), for example a military attack by third parties, is of a special and difficult kind that doesn't often arise in typical contracting, so that we can place it in a separate category and ignore it here.

The threat of physical force is an obvious way to embed a contract in the world -- have a judicial system decide what physical steps are to be taken out by an enforcement agency (including arrest, confiscation of property, etc.) in response to a breach of contract

It is what I call a reactive form of security.

The need to invoke reactive security can be minimized, but not eliminated, by making contractual arrangements verifiable

Observation of a contract in progress, in order to detect the first sign of breach and minimize losses, also is a reactive form of security

A proactive form of security is a physical mechanism that makes breach expensive

From common law, economic theory, and contractual conditions often found in practice, we can distill four basic objectives of contract design

observability

The disciplines of auditing and investigation roughly correspond with verification of contract performance

verifiability

The field of accounting is, roughly speaking, primarily concerned with making contracts an organization is involved in more observable

privity

This is a generalization of the common law principle of contract privity, which states that third parties, other than the designated arbitrators and intermediaries, should have no say in the enforcement of a contract

The field of security (especially, for smart contracts, computer and network security), roughly corresponds to the goal of privity.

enforceability

Reputation, built-in incentives, "self-enforcing" protocols, and verifiability can all play a strong part in meeting the fourth objective

Smart contracts often involve trusted third parties, exemplified by an intermediary, who is involved in the performance, and an arbitrator, who is invoked to resolve disputes arising out of performance (or lack thereof)

In smart contract design we want to get the most out of intermediaries and arbitrators, while minimizing exposure to them

Legal barriers are the most severe cost of doing business across many jurisdictions. Smart contracts can cut through this Gordian knot of jurisdictions

Where smart contracts can increase privity, they can decrease vulnerability to capricious jurisdictions

Secret sharing

The field of Electronic Data Interchange (EDI), in which elements of traditional business transactions (invoices, receipts, etc.) are exchanged electronically, sometimes including encryption and digital signature capabilities, can be viewed as a primitive forerunner to smart contracts

One important task of smart contracts, that has been largely overlooked by traditional EDI, is critical to "the meeting of the minds" that is at the heart of a contract: communicating the semantics of the protocols to the parties involved

There is ample opportunity in smart contracts for "smart fine print": actions taken by the software hidden from a party to the transaction.

Thus, via hidden action of the software, the customer is giving away information they might consider valuable or confidential, but the contract has been drafted, and transaction has been designed, in such a way as to hide those important parts of that transaction from the customer.

To properly communicate transaction semantics, we need good visual metaphors for the elements of the contract. These would hide the details of the protocol without surrendering control over the knowledge and execution of contract terms

Protocols based on mathematics, called cryptographic protocols, tre the basic building blocks that implement the improved tradeoffs between observability, verifiability, privity, and enforceability in smart contracts

secret key cryptography,

Public key cryptography

digital signatures

blind signature

Where smart contracts can increase observability or verifiability, they can decrease dependence on these obscure local legal codes and enforcement traditions

zero-knowledge interactive proof

digital mix

Keys are not necessarily tied to identities, and the task of doing such binding turns out to be more difficult than at first glance.

All public key operation are are done inside an unreadable hardware board on a machine with a very narrow serial-line connection (ie, it carries only a simple single-use protocol with well-verified security) to a dedicated firewall. Such a board is available, for example, from Kryptor, and I believe Viacrypt may also have a PGP-compatable board. This is economical for central sites, but may be less practical for normal users. Besides better security, it has the added advantage that hardware speeds up the public key computations.

If Mallet's capability is to physically sieze the machine, a weaker form of key protection will suffice. The trick is to hold the keys in volatile memory.

The data is still vulnerable to a "rubber hose attack" where the owner is coerced into revealing the hidden keys. Protection against rubber hose attacks might require some form of Shamir secret sharing which splits the keys between diverse phgsical sites.

How does Alice know she has Bob's key? Who, indeed, can be the parties to a smart contract? Can they be defined just by their keys? Do we need biometrics (such as autographs, typed-in passwords, retina scans, etc.)?

The public key cryptography software package "Pretty Good Privacy" (PGP) uses a model called "the web of trust". Alice chooses introducers whom she trusts to properly identify the map between other people and their public keys. PGP takes it from there, automatically validating any other keys that have been signed by Alice's designated introducers.

1) Does the key actually belong to whom it appears to belong? In other words, has it been certified with a trusted signature?

2) Does it belong to an introducers, someone you can trust to certify other keys?

3) Does the key belong to someone you can trust to introduce other introducers? PGP confuses this with criterion (2). It is not clear that any single person has enough judgement to properly undertake task (3), nor has a reasonable institution been proposed that will do so. This is one of the unsolved problems in smart contracts.

PGP also can be given trust ratings and programmed to compute a weighted score of validity-- for example, two marginally trusted signatures might be considered as credible as one fully trusted signature

Notaries Public Two different acts are often called "notarization". The first is simply where one swears to the truth of some affidavit before a notary or some other officer entitled to take oaths. This does not require the notary to know who the affiant is. The second act is when someone "acknowledges" before a notary that he has executed a document as ``his own act and deed.'' This second act requires the notary to know the person making the acknowledgment.

"Identity" is hardly the only thing we might want map to a key. After all, physical keys we use for our house, car, etc. are not necessarily tied to our identity -- we can loan them to trusted friends and relatives, make copies of them, etc. Indeed, in cyberspace we might create "virtual personae" to reflect such multi-person relationships, or in contrast to reflect different parts of our personality that we do not want others to link. Here is a possible classification scheme for virtual personae, pedagogically presented:

A nym is an identifier that links only a small amount of related information about a person, usually that information deemed by the nym holder to be relevant to a particular organization or community

A nym may gain reputation within its community.

With Chaumian credentials, a nym can take advantage of the positive credentials of the holder's other nyms, as provably linked by the is-a-person credential

A true name is an identifier that links many different kinds of information about an person, such as a full birth name or social security number

As in magick, knowing a true name can confer tremendous power to one's enemies

A persona is any perstient pattern of behavior, along with consistently grouped information such as key(s), name(s), network address(es), writing style, and services provided

A reputable name is a nym or true name that has a good reputation, usually because it carries many positive credentials, has a good credit rating, or is otherwise highly regarded

Reputable names can be difficult to transfer between parties, because reputation assumes persistence of behavior, but such transfer can sometimes occur (for example, the sale of brand names between companies).

Blind signatures can be used to construct digital bearer instruments, objects identified by a unique key, and issued, cleared, and redeemed by a clearing agent.

The clearing agent prevents multiple clearing of particular objects, but can be prevented from linking particular objects one or both of the clearing nyms who transferred that object

These instruments come in an "online" variety, cleared during every transfer, and thus both verifiable and observable, and an "offline" variety, which can be transfered without being cleared, but is only verifiable when finally cleared, by revealing any the clearing nym of any intermediate holder who transfered the object multiple times (a breach of contract).

To implement a full transaction of payment for services, we need more than just the digital cash protocol; we need a protocol that guarantees that service will be rendered if payment is made, and vice versa

A credential is a claim made by one party about another. A positive credential is one the second party would prefer to reveal, such as a degree from a prestigious school, while that party would prefer not to reveal a negative credential such as a bad credit rating.

A Chaumian credential is a cryptographic protocol for proving one possesses claims made about onself by other nyms, without revealing linkages between those nyms. It's based around the is-a-person credential the true name credential, used to prove the linkage of otherwise unlinkable nyms, and to prevent the transfer of nyms between parties.

Another form of credential is bearer credential, a digital bearer instrument where the object is a credential. Here the second party in the claim refers to any bearer -- the claim is tied only to the reputable name of issuing organization, not to the nym or true name of the party holding the credential.

Smart Property We can extend the concept of smart contracts to property. Smart property might be created by embedding smart contracts in physical objects. These embedded protocols would automatically give control of the keys for operating the property to the party who rightfully owns that property, based on the terms of the contract. For example, a car might be rendered inoperable unless the proper challenge-response protocol is completed with its rightful owner, preventing theft. If a loan was taken out to buy that car, and the owner failed to make payments, the smart contract could automatically invoke a lien, which returns control of the car keys to the bank. This "smart lien" might be much cheaper and more effective than a repo man. Also needed is a protocol to provably remove the lien when the loan has been paid off, as well as hardship and operational exceptions. For example, it would be rude to revoke operation of the car while it's doing 75 down the freeway.

Smart property is software or physical devices with the desired characteristics of ownership embedded into them; for example devices that can be rendered of far less value to parties who lack possesion of a key, as demonstrated via a zero knowledge interactive proof

One method of implementing smart property is thru operation necessary data (OND): data necessary to the operation of smart property.

A smart lien is the sharing of a smart property between parties, usually two parties called the owner and the lienholder.

Many parties, especially new entrants, may lack this reputation capital, and will thus need to be able to share their property with the bank via secure liens

What about extending the concept of contract to cover agreement to a prearranged set of tort laws? These tort laws would be defined by contracts between private arbitration and enforcement agencies, while customers would have a choice of jurisdictions in this system of free-market "governments".

If these privately practiced law organizations (PPLs for short) bear ultimate responsibility for the criminal activities of their customers, or need to insure lack of defection or future payments on the part of customers, they may in turn ask for liens against their customers, either in with contractual terms allowing arrest of customers under certain conditions

Other important areas of liability include consumer liability and property damage (including pollution). There need to mechanisms so that, for example, pollution damage to others' persons or property can be assessed, and liens should exist so that the polluter can be properly charged and the victims paid. Where pollution is quantifiable, as with SO2 emissions, markets can be set up to trade emission rights. The PPLs would have liens in place to monitor their customer's emissions and assess fees where emission rights have been exceeded.

The script code is unable to manipulate any assets excepting those explicitly declared beforehand on the smart contract,

Not only can the smart contract move_funds() between these declared accounts, as its script logic dictates, but it can also stash_funds() directly inside the contract itself!

A smart contract can be activated, after which point it takes on a “life of its own”

You can also define variables in your smart contract, which persist through its entire lifetime. As the smart contract—including its internal state—continues to process over time, receipts will continue to drop into the relevant parties’ inboxes,

A signed copy of the original smart contract shows it as it was, when the parties first signed and activated it. Additionally, a server-signed, updated version of the contract comes with each receipt, showing the latest state

Once the contract expires (or is deactivated) then a finalReceipt is dropped into all relevant inboxes, after which no other receipts are possible for that smart contract.

Let’s say a party needs to DIRECTLY trigger one of the clauses on the contract. (Instead of waiting around for it to trigger automatically based on some rule.) For example, perhaps an escrow user wishes to execute a clause in order to DISPUTE THE OUTCOME, or perhaps an arbitrator wishes to activate a clause in order to RENDER A JUDGMENT. OT’s smart contracts can do precisely these sorts of things, limited only by your imagination (and my pre-alpha code.)

There’s an opportunity to disrupt how those organizations work. Intermediaries, though they do a good job, have a few problems — they’re centralized, which makes them vulnerable to attack or failure

They tax the system

They capture data

They exclude billions of people from the global economy

internet of value

With blockchain, we can go from redistributing wealth to distributing value and opportunity value fairly a priori, from cradle to grave.

creating a true sharing economy by replacing service aggregators like Uber with distributed applications on the blockchain

unleashing a new age of entrepreneurship

build accountable governments through transparency, smart contracts and revitalized models of democracy.

The virtual you is owned by large intermediaries

This virtual you knows more about you than you do sometimes

So there’s a strange phenomenon from the first generation of the Internet where the most important asset class that’s been created is data —and we don’t control it or own it.

individuals taking back their identity through your own personal avatar

The financial services industry

antiquated

a complicated machine that does a simple thing

settlement

an opportunity to profoundly change the nature of the entire industry. The Starbucks transaction should be instant.

At the heart of it, the financial services industry moves value.

so this is both an existential threat to the financial services industry and an historic opportunity.

Banks trade on trust

Within the decade, every single financial asset, which is really just a contract

will all move to a blockchain-based format

In the accounting world, a lot of firms rely on costly audits to drive their profits

With blockchain, you could have a third entry time-stamped in a distributed ledger that could be acceptable to any relevant stakeholders from regulators to shareholders, giving you a perfect record of the truth and thus the financial health of an organization.

Nobel-winning economist Ronald Coase argued that firms exist because transaction costs in an open market are greater than the cost of doing things inside the boundaries of the corporation.

four costs — of search, coordination, contracting and establishing trust

Blockchains will profoundly affect all of these.

you can now synthesize trust on an open platform and people who’ve never met can trust each other to do certain things. So this results in a whole number of new business models

It turns out the Internet of Everything needs a Ledger of Everything, because a lightbulb buying power from your neighbor’s solar panel definitely won’t use banks or the Visa network

Right now, governments take tax revenue from corporations, individuals, licenses and so on. All of that can change. We can first of all have transparency in a radical sense because sunlight is the best disinfectant. Secondly, we can open up governments in a different sense of sharing data.

governments can enable self-organization to occur in society where companies, civil society organizations, NGOs, academics, foundations, and government agencies and individual citizens ought to use this data to self-organize and create what we used to call services or forms of public value. The third one has to do with the relationship between citizens and their governments.

There are more opportunities to create government by the people for the people

Electronic voting won’t be delivered by traditional server technology because it won’t be trusted by citizens