Core Mechanism: Proof of Connection (PoC)

🔗 Core Mechanism: Proof of Connection (PoC)

Proof of Connection (PoC) is the mathematical expression of “serendipity.” We not only record “meetings,” but also the “quality of interactions.” PoC is the engine of the Butterfly economic system. It converts the qualitative “met someone” into quantitative, verifiable digital events.

🧬 Anatomy of PoC

A valid PoC is not just a handshake; it is an encrypted social data “block.”

1. Discovery: Node A broadcasts a BLE beacon that contains a temporary, encrypted identity.

2. Physical constraint check: Node B receives the beacon and measures RSSI. If the signal strength is above a threshold (for example -80 dBm), it is considered within physical range.

3. Challenge-response: Node B generates an encrypted random number Nonce and sends it to Node A.

4. Multi-signature: Node A uses its Ed25519 private key to sign Nonce + Timestamp + Geohash Node B performs the same operation.

5. On-chain anchoring: The signature pairs are combined, hashed, and ultimately submitted to the blockchain (via L2 batch submission).

📐 The three-dimensional vector of the "Serendipity" algorithm

A valid connection must simultaneously satisfy verification constraints in three dimensions:

🎉1. Spatial vector (Spatial)

To prevent “teleportation attacks,” Butterfly relies on the physical attenuation characteristics of radio waves. It usesthe Log-Normal Shadowing Model to estimate distance:

$RSSI = -(10n \log_{10}(d) + A) + X_{\sigma}$

• $d$: distance between transmitter and receiver.

• $n$: path loss exponent (2 for free space, up to 4–6 in crowded indoor environments).

• $A$: RSSI value at a 1 meter reference distance.

• $X_{\sigma}$: Gaussian random variable (representing environmental noise).

Validation logic: The protocol samples RSSI multiple times within a time window $t$Only when the moving average$\overline{RSSI}$ is greater than a specific threshold (for example -70 dBm) is it considered a valid contact.

🎉2. Temporal vector (Temporal)

To prevent “replay attacks,” the handshake packet includes a high-precision nanosecond timestamp and a one-time-use random number (Nonce).

$\text{Validity} = |T_{sender} - T_{receiver}| < \Delta_{max}$

where $\Delta_{max}$ tolerates slight clock drift but will reject any historical packets.

🎉3. Cryptographic vector (Cryptographic)

A valid PoC credential must contain digital signatures from both parties.

$\text{PoC}_{asset} = \text{Sign}_A(H(ID_A, ID_B, T, \text{Nonce})) + \text{Sign}_B(H(ID_A, ID_B, T, \text{Nonce}))$

This Mutual Signature mechanism eliminates the possibility of one-sided “volume inflation.”

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🛡️ Anti-fraud mechanisms

• Physical Layer Fingerprinting: Real mobile devices exhibit characteristic fluctuation patterns in RSSI when moving. The system analyzes the variance and entropy of the RSSI sequence and rejects connections that are “too stable.”

• Graph Analysis: The graphs of volume-inflating bots often form isolated, highly interconnected “gang” structures (cliques).

• Liveness Check: Before modifying core profile data or withdrawing tokens, users must pass a live identity check using the camera (paired with a UI scanline animation).