Time Towers are a key component of StateMesh’s mechanism to facilitate the bootstrapping of nodes without reliance on traditional mechanisms such as token sales, node sales or airdrops, while simultaneously mitigating vulnerability to attacks.

This approach eliminates financial incentives to promote robust and fair network participation, enabling anyone to become a node operator.

Overview

Time Towers are StateMesh’s mechanism to ensure persistent, secure identities and verifiable metrics for node operators. Time Towers are essentially puzzle towers that act as a proof of elapsed time leveraging verifiable delay functions (VDF). A VDF is a cryptographic delay function that is designed to be computationally intensive and time-consuming to reverse engineer, making it ideal for generating secure, unique identifiers for nodes. It cannot be parallelized, ahs has no substantial benefit by using more computational resources.

Each node operator locally executes a VDF to generate proofs at regular intervals, and these proofs are chained to build its Time Tower, i.e., each proof executes from the hash of the previous proof. In addition, StateMesh reconfigures nodes participating in consensus at regular intervals by punishing unwanted behavior, for example, eliminating failed nodes.

Time Towers are stored on the StateMesh blockchain, and each node operator can have only one Time Tower. The Time Tower is used to:

• identify the node operator and to ensure that the node operator is who they say they are.
• establish a persistent identity for the node operator across reboots and network failures.
• provide a tamper-evident record of the node operator’s activity over time.
• provide a way to record node metrics and reward node operators for their contributions to the network.
• provide a way to punish node operators for malicious behavior.

The nodes which actively generate Time Tower proofs are given higher preference to execute customer workloads. Though this approach has similarities to proof of stake (PoS), it does not rely on staking financial assets to establish identities.

VDFs as Proofs of Time

Time Towers extend the traditional notion of puzzle towers by incorporating Verifiable Delay Functions (VDFs). The utilization of VDFs addresses several sustainability challenges inherent in Proof of Work (PoW) puzzles, including vulnerability to mining attacks and environmental concerns associated with excessive energy consumption.

Time Towers constitute a sequential series of cryptographic proofs, each building upon its predecessor. The process of constructing these towers is formally referred to as Proof of Time (PoT) mining, with each participating node designated as a PoT miner.

In contrast to Proof of Work (PoW) algorithms, which are inherently parallelizable and probabilistic, PoT mining is characterized by its sequential and deterministic nature. The underlying Verifiable Delay Functions (VDFs) employed in PoT mining are resistant to parallelization, thereby negating any significant advantages that might be conferred by superior hardware configurations, such as GPUs.

The construction of a Time Tower involves the iterative extension of each proof from its immediate predecessor, resulting in a rigorously ordered sequence of computational work. This architecture facilitates the establishment of persistent, verifiable identities within the network. These identities are distinguished by their permissionless and non-forgeable attributes, achievable with minimal capital investment.

Time Towers serve as a tangible manifestation of Proof of Time (PoT), with the tower’s height serving as a quantifiable metric of a node’s sustained participation in the network. This height not only demonstrates the node’s commitment to the network but also provides a robust criterion for evaluating, ranking and jailing.

Mode details on the implementation details can be found in the StateMesh documentation.

Jailing

To detect and mitigate non-compliant behavior, StateMesh employs a quantitative metric termed liveness, which serves as an indicator of a node’s active participation within a cluster. The liveness of a node is defined as the ratio of consecutive valid proofs submitted by the node during an epoch to the maximum possible number of proofs in that epoch.

At the end of each epoch, StateMesh performs a liveness assessment for all nodes. Nodes failing to meet a predetermined liveness threshold are classified as non-compliant and subjected to a jailing mechanism.

Jailed nodes forfeit their node operator status for the subsequent epoch and incur a penalty period, measured in epochs. . To regain operational status, jailed nodes must demonstrate consistent proof generation by submitting a threshold number of proofs in each epoch throughout the duration of their penalty period.

Conclusion

The Time Towers mechanism offers several advantages that merit consideration. Firstly, it significantly reduces barriers to entry by minimizing capital requirements; the ability to mine Time Towers is accessible to any individual with access to a CPU. Of particular note is the environmental sustainability of Proof of Time (PoT) mining for time towers, which utilizes minimal computational resources. This efficiency is attributed to its sequential nature, which precludes any advantages from parallelization.

Moreover, the linear growth characteristic of time towers results in a gradual diminution of the initial advantage held by genesis peers over time. This feature promotes long-term equity in participation opportunities for all interested parties.

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