Hopr – Hoprnet Token Security Audit

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Summary

ChainSecurity performed a smart contract audit of the HOPR token smart contracts.

The HOPR token implementation extends the ERC777 with a snapshot ability. Because of the data types employed, a maximum of 3.4*10^20 tokens (with 18 decimals) can exist. An additional distribution contract manages different vesting schemes. The token must be minted via a minter role, since the distribution contract calls the mint function to distribute the token. Additionally, a default admin role exists to grant permissions to the minter role. The token distribution is flexible and one account can be part of different distribution schemes.

No critical severity findings were reported. There were two high severity findings, one medium severity finding and six low severity findings. All have now been fixed in the code, with the exception of one low severity finding related to theoretical snapshotting gas costs, where the risk has been temporarily accepted.

See the report for more information on our findings.

About Hopr – Hoprnet Token

“The HOPR protocol is a layer-0 privacy foundation for anyone to build on, providing network-level and metadata privacy for every kind of data exchange. A mixnet protects the identity of both sender and recipient by routing data via multiple intermediate relay hops that mix traffic. Payments are handled via probabilistic micropayments, HOPR’s custom layer-2 scaling solution. Relay mix nodes are rewarded for their work in HOPR tokens. HOPR’s proof-of-relay mechanism protects the network from dishonest behaviour, providing everyone with economic incentives to run a global privacy network sustainably and at scale without compromising privacy.”

For more information, visit https://hoprnet.org

The ChainSecurity team went the extra mile to ensure the HOPR token and distributor contracts are secure. They even identified and resolved a complex issue in the ERC777 implementation by OpenZeppelin that's used by many projects in the space.
Dr Sebastian Bürgel, HOPR Founder