Smart Contract Access Controls

Understanding smart contract access controls is important to ensure the security and integrity of automated contracts. When Bitcoin emerged as the first cryptocurrency in 2009, very few people recognized the potential of blockchain technology. As more decentralized currencies have come online and the NFT market has grown, the world has come to realize that blockchain will shape the online world for years to come. Each day, new companies introduce blockchain-based applications in the financial, medical, and supply chain management industries.

Understanding smart contract access controls is important to ensure the security and integrity of automated contracts.

What is a smart contract?

In 1996, computer scientist Nick Szabo coined the term “smart contract.” He did not base his definition on the contract being artificially intelligent. Instead, he imagined how parties could execute a digital contract more safely and intelligently than a written one. He likened smart contracts to vending machines. Only after the purchaser makes a selection and pays a fee will the vending machine make the product available. A smart contract would be a program that could only execute after certain conditions were met.

Incorporating smart contracts into a blockchain architecture would change the culture of the internet. Subscriptions, in-app purchases and many other transactions could happen in a decentralized manner that would increase security and decrease the influence of large technology companies.

How Smart Contract Access Controls Increase Security

As with any online platform or software product, security concerns are paramount. Most transactions on blockchain involve finances, and many include private data. Although the nature of blockchain technology makes attacks more difficult, it is not invulnerable. For example, a hacker stole more than $600 million from Poly Network, a cryptocurrency platform, in August of 2021. The hacker has since returned the funds explaining that he wanted to demonstrate the security flaw.

Access controls are a primary means of improving security for smart contracts. Properly executed controls determine who can manipulate the data within the contract and handle other administrative functions. Access controls may even limit who can interact with the contract at all. A company that uses smart contracts for shareholder votes will only grant access to an approved list of members.

Two Types of Smart Contract Access Controls

The extent of access controls needed for a smart contract depends on its complexity and purpose. There are two main models of access control: ownership and role-based access.


Small organizations or contracts with a small scope may only need management by a single account. This manager has ownership of the contract and administrative access by default. Typically, the account with ownership is the same one that put the contract online. However, there are some practical considerations in accounts with a single administrator.

  • Transferring ownership: A replacement protocol must be in place if the current administrator steps down to avoid getting locked out of the smart contract.
  • Removal: If the person who set up the contract is not going to be the administrator, a removal option is necessary to prevent a backdoor vulnerability.
  • Increasing complexity: An automated smart contract can serve as the owner of another contract. This nested approach can serve to protect sensitive data.

Role-Based Access

A smart contract launched by a larger organization will often have broader access requirements. However, the sponsoring group will not want every member to have full administrative access. Role-based access involves giving layers of permission to different members of the organization. At the top level, one or two accounts will have full administrative roles. Other members may be able to interact with individual parts of the contract.

In the shareholder voting model, administrators could launch the voting app in a smart contract and grant voting privileges. Those users with mid-level access might have the authority to input names on the ballot. At the lowest level are the shareholders who can only access the contract to register a vote.

A role-based approach adds an extra level of data security. The sponsoring organization still must have other safety protocols to prevent illicit access.

  • Clear role assignment: Assigning or revoking roles should belong only to those with high-level administrative access.
  • Protective time delays: An unfaithful administrator is a security nightmare with limited solutions. One preventive step is to build the contract with alerts and time delays for unexpected actions. For a financial contract, the program could notify the organization and delay the authorization of a transaction above a certain size.

Other Preventative Steps for Access-Based Security

In addition to access controls, other security steps can prevent unauthorized activity around smart contracts.

Modular Smart Contract Design

Using a modular contract architecture is a protective model for sensitive data or transactions. Dividing data among several contracts limits the amount that an unauthorized user can access.

Regular Smart Contract Monitoring

As an organization goes live with its contracts, it should have some sense of expected behavior. Developers can build failsafe protections into the program to shut things down if conditions vary too far from the norm. For example, unexpectedly high access may point to a security vulnerability.

Smart contracts will continue to grow as a popular way to automate secure transactions. Sensible access controls and other security measures will protect organizations as they embrace blockchain technology.

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