Security Model & Bitcoin Settlement Anchoring
7.1 Security Philosophy
The Bitcoin Everlight security model is designed to complement—not replace—Bitcoin’s robust consensus mechanism. This complementary approach recognizes Bitcoin’s unparalleled security guarantees while addressing its practical limitations for everyday transactions. Everlight implements a layered security architecture that provides rapid “soft confirmations” for immediate transaction assurance, while leveraging Bitcoin’s settlement layer for ultimate finality when required.
This dual-layer approach enables a pragmatic balance between transaction speed and security assurances. By separating immediate confirmation from final settlement, Everlight creates a practical solution for everyday Bitcoin payments without compromising Bitcoin’s fundamental security properties. This separation acknowledges that different transaction contexts require different security thresholds—a small retail purchase may require only lightweight confirmation, while a high-value transfer may warrant full Bitcoin settlement.
7.2 Threat Model (High-Level)
The Everlight security model addresses specific threat vectors relevant to a lightweight transaction layer while acknowledging the boundaries of its security guarantees.
Everlight protects against the following threats:
Invalid Lightweight Transactions: The node verification process ensures that all transactions meet basic validity requirements, including proper formatting, valid signatures, and sufficient balance.
Routing Manipulation: The quorum-based confirmation model prevents individual nodes from manipulating transaction routing by requiring agreement from multiple independent nodes.
Low-Uptime Nodes: The node eligibility and reward mechanisms incentivize consistent uptime, reducing the risk of network degradation due to unreliable nodes.
Inconsistent Node Behavior: Performance monitoring and the stake-weighted reward system discourage erratic or malicious node behavior by aligning economic incentives with network reliability.
It is equally important to clarify what Everlight does NOT attempt to protect against:
Bitcoin-Level Consensus Attacks: Everlight does not provide protection against 51% attacks or other consensus-level threats to the Bitcoin network.
Deep Reorganizations: Everlight does not prevent deep blockchain reorganizations on the Bitcoin network, though the anchoring mechanism provides a reference point for reconciliation.
Protocol-Level Censorship on Bitcoin: Everlight cannot circumvent censorship that might occur at the Bitcoin protocol level, though it reduces the need for frequent Bitcoin transactions.
This clearly defined threat model establishes realistic security expectations and focuses resources on addressing the most relevant risks for a lightweight transaction layer.
7.3 Anchoring Mechanism Overview
The Bitcoin Settlement Anchoring mechanism provides a security bridge between Everlight’s lightweight confirmation layer and Bitcoin’s robust consensus. This mechanism operates through Settlement Anchoring Batches (SAB), which aggregate multiple Everlight transactions into efficient Bitcoin commitments.
A Settlement Anchoring Batch can be formally represented as:
$$\text{SAB}_n = \text{hash}({T_1, T_2, \ldots, T_k})$$
Where:
$\text{SAB}_n$ represents the $n$-th settlement anchoring batch
$\text{hash}(\cdot)$ represents a cryptographic hash function
${T_1, T_2, \ldots, T_k}$ represents a set of $k$ Everlight transactions
This batch hash is periodically committed to the Bitcoin blockchain through a standard Bitcoin transaction, creating an immutable reference that can be used to verify the integrity of the Everlight transaction history. The anchoring process is designed to be efficient, with a single Bitcoin transaction potentially representing thousands of Everlight transactions.
The anchoring mechanism is optional but provides valuable security reinforcement for scenarios requiring higher assurance levels. It creates a verifiable link between Everlight’s rapid confirmations and Bitcoin’s settlement finality without requiring every transaction to incur Bitcoin’s latency and fee costs.
7.4 Integrity Function
The overall integrity of the Everlight system can be represented through a symbolic integrity function that combines local confirmation data with Bitcoin-anchored batch data:
$$I = g(C_{\text{local}}, A_{\text{anchor}})$$
Where:
$I$ represents the integrity assurance level
$g(\cdot)$ represents the integrity evaluation function
$C_{\text{local}}$ represents local node-level confirmation data
$A_{\text{anchor}}$ represents Bitcoin-anchored batch data
This function expresses the relationship between fast local confirmations and slower base-layer anchoring. For most everyday transactions, $C_{\text{local}}$ provides sufficient integrity assurance through the quorum confirmation process. For transactions requiring higher security guarantees, $A_{\text{anchor}}$ provides additional assurance through Bitcoin’s immutable ledger.
The integrity function can be expanded to include time-dependent security considerations:
$$I(t) = \alpha \cdot C_{\text{local}}(t) + (1 - \alpha) \cdot A_{\text{anchor}}(t)$$
Where:
$I(t)$ represents the time-dependent integrity level
$\alpha$ represents a weighting coefficient $(0 \leq \alpha \leq 1)$
$t$ represents time
As $t$ increases, the contribution of $A_{\text{anchor}}$ to the overall integrity level increases, reflecting the growing security assurance provided by Bitcoin settlement over time.
7.5 Confirmation Levels
The Everlight security model implements a tiered confirmation structure that provides progressive security assurances based on transaction requirements:
L1: Instant Lightweight Confirmation (Everlight)
Initial confirmation by the first receiving node
Provides basic transaction validity assurance
Typically completed in milliseconds to seconds
L2: Quorum Confirmation (Everlight)
Confirmation by a quorum of nodes in the routing cluster
Provides strong assurance against routing manipulation
Typically completed in seconds
L3: Anchored Confirmation (Bitcoin)
Inclusion of the transaction batch in a Bitcoin settlement anchor
Provides Bitcoin-level settlement finality
Completed according to the anchoring schedule (minutes to hours)
The time relationship between these confirmation levels can be expressed as:
$$\tau_{\text{L1}} \ll \tau_{\text{L2}} \ll \tau_{\text{L3}}$$
Where $\tau$ represents the time to reach each confirmation level.
This tiered structure allows users to select the appropriate confirmation level based on their specific security requirements and time constraints. For most everyday transactions, L2 confirmation provides sufficient security assurance with minimal latency.
7.6 Quorum Safety
The quorum-based confirmation model is a core security mechanism in the Everlight system. It requires agreement from a sufficient subset of nodes before a transaction is considered confirmed, reducing the risk of manipulation by individual nodes.
The quorum rule can be formally expressed as:
$$|N_{\text{confirm}}| \geq Q = \lceil k \cdot N_{\text{cluster}} \rceil$$
Where:
$|N_{\text{confirm}}|$ represents the number of confirming nodes
$Q$ represents the minimum quorum threshold
$k$ represents the quorum coefficient $(0 < k \leq 1)$
$N_{\text{cluster}}$ represents the total number of nodes in the routing cluster
$\lceil \cdot \rceil$ represents the ceiling function
This quorum approach provides security against manipulation attempts by requiring an attacker to control a significant portion of the node network. The specific value of $k$ is a critical security parameter that balances confirmation speed with security assurance.
The security properties of the quorum system can be analyzed using a probabilistic model:
$$P(\text{manipulation}) \leq \binom{N_{\text{cluster}}}{Q} \cdot p^Q \cdot (1-p)^{N_{\text{cluster}}-Q}$$
Where:
$P(\text{manipulation})$ represents the probability of successful manipulation
$p$ represents the probability of a node being compromised
$\binom{N_{\text{cluster}}}{Q}$ represents the binomial coefficient
This model demonstrates that as $Q$ increases relative to $N_{\text{cluster}}$, the probability of successful manipulation decreases exponentially, providing strong security guarantees for the quorum confirmation process.
7.7 Anchor Frequency Model
The frequency of Bitcoin settlement anchoring is a configurable parameter that balances security assurance with operational efficiency. This frequency can be expressed as:
$$f_{\text{anchor}} = \frac{1}{\Delta}$$
Where:
$f_{\text{anchor}}$ represents the anchoring frequency
$\Delta$ represents the anchoring interval (measured in time or transaction volume)
The anchoring interval $\Delta$ is adjustable based on network conditions, security requirements, and operational considerations. During periods of high transaction volume or elevated security concerns, $\Delta$ may be decreased to provide more frequent anchoring. Conversely, during normal operations, $\Delta$ may be increased to optimize for efficiency.
The anchoring frequency can also be expressed in terms of transaction volume:
$$f_{\text{anchor}} = \frac{1}{\max(T_{\text{min}}, \min(T_{\text{current}}, T_{\text{max}}))}$$
Where:
$T_{\text{min}}$ represents the minimum transaction threshold for anchoring
$T_{\text{current}}$ represents the current transaction count since last anchoring
$T_{\text{max}}$ represents the maximum transaction threshold for anchoring
This adaptive approach ensures that anchoring occurs at appropriate intervals based on actual network usage, providing efficient security reinforcement without unnecessary Bitcoin transactions.
7.8 Conceptual Diagram
The relationship between Everlight’s lightweight confirmation layer and Bitcoin’s settlement layer can be visualized through the following conceptual diagram:
This diagram illustrates the progressive security model, where transactions receive rapid confirmation through the Everlight node network, followed by optional settlement anchoring to the Bitcoin blockchain for additional security assurance.
7.9 Security Assumptions
These security assumptions form the foundation of Everlight’s security model. They establish realistic expectations about the system’s security properties while acknowledging the inherent trade-offs involved in a lightweight transaction layer.
7.10 Summary
The Bitcoin Everlight security model creates a pragmatic balance between transaction speed and security assurance through a layered approach:
Everlight offers speed via lightweight confirmation, enabling near-instantaneous transaction assurance for everyday payments without the latency of Bitcoin block confirmations.
Bitcoin provides long-term settlement assurance through the optional anchoring mechanism, leveraging Bitcoin’s robust consensus for ultimate transaction finality when required.
Together, they create a practical, secure, and scalable Bitcoin payment experience that addresses the limitations of existing approaches while maintaining compatibility with Bitcoin’s security foundation.
This dual-layer security model acknowledges that different transaction contexts require different security thresholds. By providing a spectrum of confirmation levels from rapid lightweight verification to full Bitcoin settlement, Everlight enables users to select the appropriate security-speed trade-off for their specific use case.
The security model is deliberately conservative in its claims, focusing on practical payment scenarios rather than attempting to replicate Bitcoin’s full security guarantees at the lightweight layer. This pragmatic approach recognizes Bitcoin’s role as the ultimate settlement layer while extending its practical utility through a complementary lightweight transaction layer.
Last updated