Engineering · 2026-03-16

Physics-Anchored Identity Settlement Tokens: Proof of Presence

By J. W. Bouckaert

The problem with every token system in production

Physics-anchored identity settlement tokens are a research design described in PasskeyBridge's filed patent applications. The current product issues no tokens.

Every cryptographic token deployed at scale today derives its value and integrity from one of three proof mechanisms:

1. Proof-of-work (Bitcoin): value is anchored to computational expenditure. The more energy consumed, the more secure the network. The proof is thermodynamic, but the thermodynamics are artificial: the work being performed (iterating SHA-256 nonces) serves no purpose beyond the proof itself.

1. Proof-of-stake (Ethereum post-Merge): value is anchored to economic collateral. Validators lock capital to earn the right to propose blocks. The proof is financial: the more capital at risk, the less incentive to defect. This replaces energy expenditure with plutocratic governance.

1. Proof-of-authority (stablecoins, CBDCs): value is anchored to institutional backing. A central issuer guarantees redemption. The proof is legal and reputational: the token is worth what the issuer says it is worth, contingent on the issuer remaining solvent and trustworthy.

Each of these mechanisms has produced systems of extraordinary scale. Bitcoin's market capitalization has exceeded a trillion dollars, secured by proof-of-work. Ethereum's move to proof-of-stake reduced its energy consumption by about 99.95%. Stablecoins like USDC and USDT are widely used for payment and trading settlement.

None of them prove that a human being was physically present at the hardware that initiated the transaction.

That gap is the attack surface that enables every key-theft, SIM-swap, and credential-replay attack in the identity space. A stolen private key grants the same transactional authority as a legitimately held one. A compromised passkey passes the same cryptographic challenge as the original. There is no physics in the loop. The proof is purely mathematical, and mathematics does not care who is holding the device.

The fourth primitive: Proof-of-presence

Physics-Anchored Identity Settlement Tokens introduce a fundamentally different proof mechanism. Instead of proving that computational work was performed, that economic capital was staked, or that an institution authorized issuance, a token proves that a human being was physically present at specific hardware in a specific electromagnetic environment at the moment of minting.

This proof is derived from three independent physics channels, evaluated with strict AND logic:

Channel 1: Atomic Fingerprint. The minting device captures a multi-modal fingerprint comprising electromagnetic interference (EMI) spectral patterns, thermal noise variance from the device's processor, accelerometer micro-vibration signatures, and network jitter entropy. This capture completes within 100 milliseconds. Each channel is reduced to a SHA-256 digest on the device, and the channel digests are combined into one composite SHA-256 fingerprint. The server stores the composite and channel digests as the device sent them, without a key. The device identifier digest comes from guessable inputs such as user agent, screen size and timezone, so the server keys it with HMAC-SHA-256 under a server-held pepper before storage. At verification, the server compares the new capture with the enrolled baseline. A different device identifier fails the check, and so do EMI and thermal digests identical to the baseline, which the server treats as a suspected replay.

Channel 2: Kinematic Handshake. The system verifies the device's physical position through one of two modalities: LEO satellite Doppler-shift variance (when non-terrestrial network connectivity is available) or terrestrial carrier-signal jitter patterns (via the device's cellular radio). When both modalities are available simultaneously, the system operates in hybrid mode, producing a combined kinematic coefficient with elevated trust weight. This channel proves that the device exists in physical space, beyond the reach of a virtual machine, emulator, or replay environment.

Channel 3: Quorum Attestation. A minimum of two proximity-verified devices must independently confirm the minting event. Proximity is established through a cascade of ranging protocols: Ultra-Wideband (UWB) at centimeter precision, Bluetooth Low Energy (BLE) as fallback, and LEO Doppler-correlation as tertiary fallback. The quorum requirement eliminates single-device replay attacks: a stolen device alone cannot pass the attestation without a co-located senior quorum member.

All three channels must pass, and a single channel failure rejects the minting request.

Physics-based and mathematical proof

The distinction between physics-based and mathematics-based proof has direct security implications that cascade through the entire token lifecycle.

A mathematical proof (a digital signature, a hash preimage, a zero-knowledge proof) can be computed by any entity that possesses the correct inputs. If an attacker obtains a private key, they can produce signatures indistinguishable from the legitimate key holder's. The signature shows that the signer held the secret.

A physics-based proof encodes something that cannot be transferred: the physical state of specific hardware in a specific environment at a specific moment. The thermodynamic noise pattern of a processor is a function of its manufacturing tolerances, ambient temperature, power supply characteristics, and electromagnetic environment. The Doppler-shift signature of a LEO satellite pass is a function of the device's geographic position, the satellite's orbital parameters, and the precise moment of observation. The design relies on these signals being hard to reproduce without the hardware at that place and time.

This distinction has three consequences for token security:

1. Minting requires presence as well as the key. An attacker who compromises a device's private keys cannot mint new tokens without being physically present at the device, in the correct electromagnetic environment, with a co-located quorum member.

2. The physics channels take sensor evidence from the device. In the design, the three-channel AND gate accepts sensor evidence captured on the minting device, so AI-generated audio, video and biometric data have no input path to it.

3. Replay attacks are temporally bounded. In the design, each Atomic Fingerprint capture includes time-variant components (thermal drift, network jitter), so an earlier capture should not match a fresh one. In the current code, the server refuses a capture whose timestamp is more than 500 ms from server time, and it flags EMI and thermal digests identical to the enrolled baseline as a suspected replay.

The token lifecycle

A token progresses through a defined lifecycle, with every transition recorded in a quantum-resistant provenance chain:

Minting

In the filed design, the minting process would begin when a token holder initiates a mint request. The three-channel physics verification would execute in parallel, with the AND gate evaluating all channel results before proceeding. Upon successful verification, the design specifies that:

• A unique token identifier is generated via a quantum-seeded deterministic random bit generator (QRNG-DRBG), sourced from a four-tier entropy hierarchy
• The holder's identity binding is hashed with SHA-256, as filed. That is an unkeyed digest; the shipped product keys low-entropy identifiers with HMAC-SHA-256 under a server-held pepper instead
• A hybrid PQC signature is computed over the minting event: HMAC-SHA-256 for classical integrity, plus ML-DSA-65 (NIST FIPS 204) for quantum resistance
• The provenance chain receives its genesis entry, signed with a quantum-seeded nonce

In the filed design, the resulting token is recorded in a zero-PII settlement ledger as a tuple: token identifier, holder hash, denomination, attestation references, and provenance chain. The application describes a ledger that stores no personally identifiable information at any point, so that the ledger operator could not determine the real-world identity of any token holder from stored data alone. The current product has no such ledger.

Transfer

Token transfer introduces the mechanism that most fundamentally differentiates from existing token systems: dual proof-of-presence.

Both the sender and the recipient must independently complete a full three-channel physics verification before the transfer executes. The protocol operates as follows:

1. Sender and recipient establish a BLAST tunnel (X25519 ECDH, optionally combined with ML-KEM-768, with a quantum-seeded HKDF-SHA-256 salt) for encrypted communication with forward secrecy
2. Sender re-attests through three-channel physics verification
3. Recipient independently re-attests through three-channel physics verification
4. Both attestation results are verified by the settlement engine
5. The provenance chain receives a transfer entry signed by both parties' attestation hashes

In the filed design, moving a token requires the private key and the physical presence of both parties. Even if an attacker compromises the sender's private key, they cannot execute a transfer without the sender being physically present at their hardware. And even if the attacker physically possesses the sender's device, the transfer still requires the recipient to independently prove their own physical presence.

Splitting and merging

Settlement tokens support deterministic splitting and merging with full provenance chain inheritance:

• Split: A parent token of denomination N can be split into K child tokens whose denominations sum to N. Each child inherits the parent's full provenance chain and receives a fresh hybrid PQC signature at the split event. The parent transitions to a terminal "redeemed" status.
• Merge: Multiple tokens held by the same holder (verified by physics attestation) can be merged into a single token whose denomination equals the sum of the inputs. All input provenance chains are concatenated into the output token's provenance chain.

In both cases, the operation requires a fresh three-channel physics verification, ensuring that no splitting or merging occurs without the holder's physical presence.

Revocation

Settlement tokens integrate with the parametric revocation cascade. When a Hard Signal is detected from the carrier signal ingestion pipeline (Pillar I), the design has all tokens associated with the compromised identity hash move atomically to a "frozen" status. That would sit beside what a hard signal does in the product today: it deactivates every active agent delegate in the tenant, revokes the tenant's A2A negotiations and freezes the subject's shadow identities, and the tenant's playbook can also tear down BLAST sessions.

Unfreezing requires the holder to complete a full three-channel physics re-verification, proving that the physical human is still in control of the hardware constellation.

Hardware succession

Token ownership must persist across hardware transitions. Devices break, are lost, or are upgraded. The Entropy Succession Token (EST) mechanism enables this without centralized recovery:

1. The holder initiates succession from their existing hardware constellation
2. Both old and new hardware independently complete three-channel physics verification
3. The holder hash is re-derived under the new constellation's attestation data
4. A succession event is appended to every token's provenance chain, signed by both old and new constellations' hybrid PQC signatures

This is the Ship of Theseus for digital identity: the holder's identity persists even as every physical component is replaced, because the design binds the identity to the physics of the holder's relationship with hardware.

The zero-PII settlement ledger design

Patent application describes a settlement ledger design that stores only hashes and non-identifying fields. The current product has no such ledger. As filed, it stores the following for each token:

Under the filed design, the ledger operator, even with full database access, could not determine who holds a token, where they are located, or what device they used. Ownership would be proven by a combination of knowledge (the holder's identity binding inputs) and presence (three-channel physics verification). That is a different trust model from blockchain systems, where ownership is proven solely by knowledge of a private key.

Quantum resistance

Every signature in the lifecycle uses a hybrid construction: HMAC-SHA-256 for classical integrity, plus ML-DSA-65 (NIST FIPS 204, formerly CRYSTALS-Dilithium) for post-quantum resistance. ML-DSA-87 (FIPS 204 security category 5, the parameter set CNSA 2.0 specifies for national security systems) is already available to Enterprise tenants for credentials, and the design would use it where CNSA 2.0 applies.

The provenance chain is append-only by construction. Each entry's signature covers the hash of the previous entry, creating a hash chain that cannot be retroactively modified without invalidating all subsequent entries. This property holds even against a cryptographically relevant quantum computer (CRQC), because the ML-DSA component of the hybrid signature is lattice-based and resistant to Shor's algorithm.

Prior art and differentiation

The mechanism builds on and differentiates from existing systems:

The fundamental innovation is the scarcity primitive. Bitcoin's scarcity derives from computational difficulty. Ethereum's derives from economic stake. Stablecoin scarcity is institutional. scarcity would derive from physics: the design requires a human being physically present at hardware to mint a token, and is meant to make that presence hard to fake, replay, or delegate without physical cooperation.

The earning model

In the filed design, tokens are earned through verified physical presence during platform engagement and authentication events. Each successful three-channel physics verification during an identity authentication ceremony adds to the holder's trust credits, which record verified proof-of-presence events and carry settlement value. Trust credits and their settlement value are a design in the filed patents; the current product issues no tokens and records no trust credits.

Cryptocurrency mining rewards computational work and binds no identity. In the filed design, a credit is recorded only after a three-channel physics verification at the holder's hardware.

Implications

In the filed design, the unit of value is a verified presence event at specific hardware.

The filed design has these implications:

• Data minimization: a settlement token that proves physical presence without storing PII fits the data-minimization principles of GDPR and CCPA. It does not replace KYC (know your customer), which needs identity evidence.
• Anti-fraud: a transfer requires proof of presence from both sender and recipient, so a stolen private key alone cannot move a token.
• Sensor binding: a spatial verification compares the new sensor digests with the enrolled baseline. In the current code, it fails when the device identifier differs from the baseline or when the EMI and thermal digests repeat the baseline exactly. The server receives digests of the readings, so it checks consistency with enrollment. How the readings were produced is outside what it checks.

Proof-of-work proves computation, proof-of-stake proves capital at risk, and a guarantee proves an issuer's commitment. This design is meant to prove presence at specific hardware.

Start free · Test the API