Announcing Hermes — Collateralized Token Bridging

There are 7 proprietary innovations that deliver Partisia Blockchain’s complete Layer 1+2 Blockchain. In this blog we present the third innovative feature — the token bridge — we call it, Hermes.

For an overview of all of the 7 features see the Zeus blog. We present each of the 7 innovations with a unique post leading up to TGE on May 31, 2022.

Hermes — Collateralized Token Bridging

The evolution and innovation around blockchain technologies has resulted in a variety of different blockchain networks with different strengths and weaknesses. This development will likely continue and interoperability and token bridges as the most prominent instrument, has become a major value creator in the blockchain ecosystem. Designing secure token bridges is, however, a significant challenge as values are moved out of the security model backing the involved tokens.

Partisia Blockchain has designed a new type of token bridge that addresses existing weaknesses. This is an important innovation as any use of Partisia Blockchain involves external coins, hence, token bridges are part of the very backbone of the blockchain network. We believe this is a superior foundation for a more solid token bridge.

The Partisia Blockchain token bridge model utilizes a number of cryptographic tools and basic economic principles. The core basic principle is a collateralized token transfer represented 1 to 1 across two independent blockchain networks, which basically mimics a double booking system that has proven its worth since the Medici Bank in the 14th century. The challenge is to simultaneously represent and work with states from two independent blockchains as efficiently and as securely as possible. The token bridge is illustrated and briefly described below.

The illustration captures the three main components of the token bridge around the two basic operations — depositing and withdrawing values.

The first part is the double bookkeeping principle within regularly expiring epochs: The process ensures that the information is persisted on both blockchains and establishes a straightforward auditability that is easily accessible by all users and node operators. Deposit and withdrawal is managed by a small set of independently selected Oracle nodes — the small Oracle — in expiring epochs as further described below.

The second part is the collateralized bridging within the regularly expiring epochs: The small Oracle consists of Oracle nodes with sufficiently available MPC tokens that function as locked collateral during an epoch. The epoch expires when the small Oracle runs out of MPC tokens as collateral. In the following epoch any holder of MPC tokens can stake to run a dispute in case of fraud.

The third part is a secure selection of small Oracles: An MPC based signature scheme operated by the large Oracle (i.e. all available baker nodes) ensures that the selection of the next small Oracle matches the security of the consensus model. The large Oracle is also responsible for delegating the job of mirroring the identity of the members of both the small and the large Oracle to the partner chain. With that in place, the double bookkeeping is securely established.

For more details, please checkout the yellow paper and software documentation.

Please let us know what you think and stay tuned for the next blog post about the zero-knowledge layer, called Athena.

Thank you to everyone in our community for your support!

Partisia Blockchain Team