Development Philosophy

• Prepare for failure. Any non-trivial contract will have errors in it. Your code must therefore be able to respond to bugs and vulnerabilities gracefully.

  • Pause the contract when things are going wrong ('circuit breaker')
  • Manage the amount of money at risk (rate limiting, maximum usage)
  • Have an effective upgrade path for bugfixes and improvements

• Rollout carefully. It is always better to catch bugs before a full production release.

  • Test contracts thoroughly, and add tests whenever new attack vectors are discovered
  • Provide bug bounties starting from alpha testnet releases
  • Rollout in phases, with increasing usage and testing in each phase

• Keep contracts simple. Complexity increases the likelihood of errors.

  • Ensure the contract logic is simple
  • Modularize code to keep contracts and functions small
  • Use already-written tools or code where possible (eg. don't roll your own random number generator)
  • Prefer clarity to performance whenever possible
  • Only use the blockchain for the parts of your system that require decentralization

• Stay up to date. Use the resources listed in the next section to keep track of new security developments.

  • Check your contracts for any new bug that's discovered
  • Upgrade to the latest version of any tool or library as soon as possible
  • Adopt new security techniques that appear useful

• Be aware of blockchain properties. While much of your programming experience will be relevant to Ethereum programming, there are some pitfalls to be aware of.

  • Be extremely careful about external contract calls, which may execute malicious code and change control flow.
  • Understand that your public functions are public, and may be called maliciously. Your private data is also viewable by anyone.
  • Keep gas costs and the block gas limit in mind.