Abhishek S.
Shipping in public. Listening in private.

Abhishek

I lead women’s Indo-Western & Premium at Max Fashion. I also wrote the AI that runs the buying floor.

Rare profile. Category operator who ships production code.

Senior Buying Leader · Max Fashion Women’s Indo-Western & Premium · 530+ India stores NIFT ’12 · Twelve years on the floor

read the CV start a letter
abhishek@bengaluru ~ %
>role: senior buying lead
>dept: women’s indo-western + premium
>floor: 530+ stores india

Zero-Knowledge Proofs as Judicial Evidence — Proof Without Explanation

Courts have operated for millennia on an implicit assumption: conviction requires explanation. A verdict requires a jury to understand the reasoning, an alibi requires a witness or documentary trace, and evidence requires a chain of custody anyone can follow. Zero-knowledge cryptography is the first formal system that breaks this assumption — and a small but growing body of legal scholarship is starting to ask whether that matters for criminal defense.

The Setup

A zero-knowledge proof allows a prover to convince a verifier that a statement is true without revealing why it is true or any information beyond the truth value itself. Full technical background: concept zero knowledge proofs.

The judicial version of this question is: can a defendant prove innocence to a court without revealing the underlying facts of their private life?

The canonical scenario is the location alibi. A defendant is accused of committing a crime in City A at 11 PM. They were actually at a private address in City B — but the address reveals an affair, an undisclosed medical appointment, an illegal but victimless activity, or simply a relationship they don't want exposed. Standard alibi evidence (cell tower records, receipts, witness testimony) would prove their location and also expose the private information. A ZKP alibi would prove "I was not in City A at 11 PM" without revealing where they were.

What the Law Currently Requires

Alibi evidence has no formal proof standard beyond the reasonable-doubt threshold. Courts accept:

None of these require a formal proof of truth — they all rely on the credibility of the evidence source. Cell tower records can be falsified; witnesses can lie; receipts can be forged. Courts assess credibility, not mathematical proof. This is by design: the adversarial system is built around human judgment, not machine verification.

A ZKP alibi would be mathematically verifiable under the hardness assumptions of the cryptographic system. A valid proof cannot be forged without breaking the underlying mathematics (e.g., discrete logarithm or hash preimage). This is a qualitatively different standard from any existing evidence category.

Academic Precedent: Reconciling Secrecy and Fair Trial Rights

A 2022 paper by Bitan, Canetti, Goldwasser, and Wexler — "Using Zero-Knowledge to Reconcile Law Enforcement Secrecy and Fair Trial Rights in Criminal Cases" (ACM/SSRN 4074315) — addressed the law enforcement side of the same coin: how can police use proprietary forensic software as evidence without revealing the software's code (which they argue exposes investigative methods)?

Their proposal: ZKP allows a law enforcement prover to demonstrate that forensic software produced a specific output from a specific input without revealing the software itself. Defense experts can verify the computation without accessing the source code. This is the inverse of the alibi problem — law enforcement wants to prove something to the court without revealing how they know it — but the mathematical structure is identical.

The 2025 Springer chapter "Privacy Paradigm Shift: Zero Knowledge Proofs in Criminal e-Evidence Collection" extended this to the alibi direction: ZKPs in e-evidence collection frameworks that explicitly address location-based alibi defense without requiring full disclosure of location history.

What the Ilango 2025 Result Changes

Prior ZKP systems for large-scale deployment fell into two families:

Rahul Ilango's July 2025 result (IACR ePrint 2025/1296, "Gödel in Cryptography: Effectively Zero-Knowledge Proofs for NP with No Interaction, No Setup, and Perfect Soundness") removed the trusted-setup requirement entirely — and also removed the interaction requirement. A single message from prover to verifier, with no ceremony and with perfect soundness, is now achievable.

The judicial implication: a defendant could, in principle, generate their own ZKP proof of alibi without requiring any trusted third party, ceremony, or interactive exchange with the court. The proof would be a single document the court could verify. The defendant would retain their secrets.

However, perfect soundness in Ilango's construction comes at a definitional cost: the security guarantee relies on the unprovability of the simulator's non-existence in ZFC. The proof is not "the simulator doesn't exist" but "it's impossible to prove the simulator doesn't exist." This is technically secure but is not the kind of guarantee a legal standard would naturally express.

The Due Process Tension

Legal systems don't just verify truth — they require explainable truth. The core due process right in adversarial systems is the right to confront evidence: to examine, test, and challenge it. A mathematical proof is opaque to a lay jury even if it is perfectly sound. Three tensions emerge:

1. Verifiability without comprehensibility

A judge could in principle have a court-appointed cryptographer verify a ZKP alibi. But the jury would need to accept the cryptographer's testimony on faith. This is analogous to DNA evidence — juries routinely accept forensic evidence they cannot independently assess. The ZKP case is stronger: unlike DNA evidence, a valid ZKP proof cannot be wrong under the security assumptions. But the jury has no way to distinguish a valid from an invalid proof except by trusting the verifier.

2. The Chinese Room in court

concept chinese room asks whether understanding accompanies verification: a system manipulating symbols correctly might understand nothing. A jury accepting a ZKP alibi confronts the same question institutionally: what does conviction require if it doesn't require comprehension of the evidence?

3. Range proofs and geographic vagueness

ZKP range proofs (using Bulletproofs or STARK constructions) allow proving membership in a set without revealing which member. Applied to location, this means proving "I was within 100 km of my home at 11 PM" without revealing the exact location. This is a weaker claim than a full alibi but may suffice for establishing "I was not in City A" — and it avoids exposing specific location. The graduated disclosure possibility — proving increasingly specific location claims under oath, stopping at the resolution that establishes innocence — is unexplored in legal scholarship.

Connections to the Wider Wiki

Cryptography × Philosophy (ZKP as Epistemological Wedge): The Voynich Manuscript achieves what concept voynich five scribes hoax calls an "accidental zero-knowledge proof" — it proves the existence of a generating mechanism without revealing what it is. The five scribes' production commits to a system no one can crack. A judicial ZKP would be the intentional version: a defendant commits to innocence (the system exists) without revealing their alibi (the mechanism). The manuscript and the alibi proof share the same deep structure.

Cryptography × Religion (Aniconic Deities as ZKPs): concept aniconic smith gods notes that the aniconic linga of Vishwakarma and Yahweh's absence of images function as commitment schemes — they prove the existence of sacred knowledge (the creative principle) without revealing the secret (the craft technique). The judicial ZKP is this structure formalized in mathematics: a commitment to truth without disclosure of the truth's content.

Physics × Cryptography (Gödel Machinery Applied Twice): The 2025 Ilango result imports Gödel's incompleteness theorems into cryptography. The same machinery appears in concept godel incompleteness as a limit on physics (the spectral gap of quantum Hamiltonians is undecidable). The pattern: Gödel's unprovability is a resource that can be exploited — in cryptography for security, and potentially in physics for fundamental limits. Courts requiring explainable proofs would be resisting the same mathematical structure that says the universe has irreducible true-but-unprovable propositions.

Privacy × Law: EU GDPR already creates legal pressure to minimize disclosed personal data. ZKP-based identity wallets (EU Digital Identity Wallet, active 2025–2026) prove attributes ("I am over 18") without disclosing birth dates. The judicial alibi use case is an extension of the same architecture to a higher-stakes context.

An Open Question

If a ZKP alibi becomes legally admissible, who administers the proof? The defendant needs to prove "I was at location X at time T." They presumably know X, but the court needs to trust that the proof was generated honestly against a real location trace, not a fabricated one. In standard ZKPs, the prover's knowledge of the witness is what grounds the proof. For a location alibi, the witness is the actual location — but location traces come from devices (phones, cards, cameras) controlled by third parties. Does a ZKP alibi require a trusted location-data custodian to act as the honest prover?

This is the institutional gap. The mathematics is solved. The infrastructure chain — honest location data → honest proof generation → court verification — requires a new kind of trusted party that doesn't yet exist in the legal system.

Key Sources

See Also