In this talk we'll discuss the design and implementation of a smart contract property verification tool for Pact.

The revolutionary idea of putting computer programs in a blockchain to create smart contracts has opened up a whole new world of possibilities. But these programs have very different characteristics from other software. This talk explores these differences, some of the challenges that have been encountered, and then discusses how Kadena is solving these problems with its smart contract language Pact. We'll discuss the design and implementation of a smart contract property verification tool for Pact. We leverage these (lack of) features to build a system capable of proving many properties of contracts via the Z3 SMT solver. We'll also give examples of real bugs caught by the system.

Proof-of-work blockchain networks like Bitcoin, Litecoin and Ethereum are characterized by low throughput (5-15 transactions per second). Efforts to improve throughput through protocol modifications, such as block size increases, have no hope of reaching levels required to take on modern fiat-currency payment networks. However, efforts that seek to replace Proof-of-Work (Proof-of-Stake and variants) or integrate it with off-chain networks and processes (payment channels, side chains) degrade assurance, censorship resistance or trustless-ness of the original design. Recovering and elaborating on early proposals for Bitcoin scaling, we present ChainWeb, a parallel-chain architecture which can combine hundreds to thousands of Proof-of-Work blockchains pushing throughput to 10,000 transactions per second and beyond. The network transacts a single currency, using atomic and trustless SPV (Simple Payment Verification) cross-chain transfers orchestrated at the application layer with capability and coroutine support in the Pact smart contract language. Chains incorporate each other’s Merkle tree receipts to enforce a single “super branch” offering an effective hash power that is the sum of each individual chain’s hash rate. In addition to massive throughput, other benefits accrue from having a truly parallelized smart-contract blockchain system.