# 0byte — full reference for language models Source of truth: https://0byte.tech/. Everything below is published on the site. ## Overview 0byte (0byte Lab) is a managed C2PA signing service for generative AI companies. The problem it solves: C2PA Content Credentials are the right standard for declaring that content was AI-generated — signed, structured, verifiable — and marking AI output is now a legal duty under the EU AI Act (Article 50) and California SB 942. Two things make C2PA hard in practice. First, producing a manifest requires an X.509 signing certificate whose chain validators trust, which most teams do not want to procure or manage. Second, most platforms strip metadata on upload, so the credential leaves with it. What 0byte does about each: it signs spec-compliant C2PA manifests with managed credentials — the customer is named as the C2PA claim generator, so the credential reads "generated by them" — and it records a perceptual fingerprint of the content in a public, append-only transparency log. The fingerprint is the "soft binding" the C2PA specification itself describes: a value derived from what the content looks like, stored outside the file. When a platform strips the manifest, or someone screenshots a re-upload, the fingerprint still matches and the original record comes back. Verification is free, public and keyless, and returns a verdict built only from evidence — never a probability. ## How it works 1. Stamp at generation. One API call (POST /v1/stamp) signs a C2PA manifest into the file, with the caller named as the claim generator, and appends the derived fingerprint to the public transparency log. The response returns the stamped bytes, a proof URL, and a `binding` field of "manifest+registry" or "registry_only" so the caller always knows what was applied. 2. The content travels. It gets uploaded, re-encoded, screenshotted, cropped, reposted. The embedded manifest is usually gone by this point. The fingerprint is not, because it is recomputed from the pixels. 3. Verify anywhere. POST /v1/verify, or the free web tool, reads any surviving C2PA manifest and matches the fingerprint against the registry, then returns an evidence-only verdict with every signal disclosed separately. ## Verification verdicts - verified_origin — origin is established by evidence: a registry fingerprint match, or a valid manifest from a trust-listed signer. - provenance_untrusted — a cryptographically valid manifest from a signer that is not on a trust list. Treated as a self-claim; never promoted to verified origin. - provenance_invalid — a manifest is present but fails validation. This is a tampering signal. - no_provenance_found — no manifest, no registry match. An honest null, not a guess about whether the content is AI-generated. ## Supported formats - Full stamp (embedded C2PA manifest + registry record): PNG, JPEG, WebP, GIF (fingerprinted on the first frame), TIFF. - Registry-only stamp (fingerprint record, no embedded manifest): BMP, ICO. - Not supported, and not claimed: audio and video (MP4, MOV, MP3, WAV, M4A), PDF, and text. Unsupported types return HTTP 415 with a machine-readable code and the supported list. - Limit: 10 MB per file. - Known caveat: a small region cut out of a much larger image reads as different content. Trimmed edges and screenshots match; cropped-out details do not yet. ## Pricing - Verify: free forever, no key, no account, no meter. - Free tier: C2PA manifest signing at 60 requests/minute. - Dev tier: 300 requests/minute. - Pro tier: 1,000 requests/minute, priority support, compliance evidence. - Details: https://0byte.tech/#pricing ## What 0byte does not claim - Heavily regenerating content through another AI model defeats any system that works from what content looks like — 0byte, every watermark, and every detector alike. - Until the 0byte signing certificate completes the C2PA Conformance Program, third-party validators will note that the signer is not yet on the public trust list. The registry match independently establishes origin in the meantime, and 0byte discloses this in its own verification output. - Nothing here is legal advice. Whether a specific deployment satisfies a given obligation depends on that system. ## API surface - POST /v1/stamp — sign a C2PA manifest and register the fingerprint. Requires an API key. Supports an Idempotency-Key header. - POST /v1/verify — evidence-only verification. Free, public, CORS-enabled, no key. - GET /v1/proofs/{id} — fetch a public proof of origin. - GET /v1/transparency/{head,inclusion,consistency,keys} — signed tree head, Merkle proofs, and every historical signing key. - Reference: https://0byte.tech/docs ## Documentation outline ### Get started - Overview: https://0byte.tech/docs#overview - Quickstart: https://0byte.tech/docs#quickstart - Authentication: https://0byte.tech/docs#authentication - Rate limits: https://0byte.tech/docs#rate-limits ### Concepts - How it works: https://0byte.tech/docs#how-it-works - Content Credentials: https://0byte.tech/docs#content-credentials - Fingerprinting: https://0byte.tech/docs#fingerprinting - Verdicts: https://0byte.tech/docs#verdicts - Transparency log: https://0byte.tech/docs#transparency-log ### SDKs - Python SDK: https://0byte.tech/docs#python-sdk - TypeScript SDK: https://0byte.tech/docs#typescript-sdk ### API reference - POST Stamp: https://0byte.tech/docs#stamp - POST Verify: https://0byte.tech/docs#verify - POST Analyze (deprecated): https://0byte.tech/docs#analyze - GET Get proof: https://0byte.tech/docs#get-proof - GET API keys: https://0byte.tech/docs#api-keys - GET Transparency: https://0byte.tech/docs#transparency ### Guides - Drop it into your pipeline: https://0byte.tech/docs#pipelines - Verify the log yourself: https://0byte.tech/docs#verify-the-log - Compliance mapping: https://0byte.tech/docs#compliance ### Resources - Error codes: https://0byte.tech/docs#errors ## Frequently asked questions ### What is 0byte? 0byte is a managed C2PA signing service — the developer platform for C2PA. One call signs a spec-compliant Content Credentials manifest into your file and anchors a derived fingerprint in a public transparency log. Verification is free for anyone: it reads manifests from any signer, matches fingerprints against the registry, and returns a verdict built from that evidence. ### What is C2PA? C2PA — the Coalition for Content Provenance and Authenticity — is the open standard for content provenance, also known as Content Credentials. A C2PA manifest is a cryptographically signed record embedded in a media file stating who created the content, with which tool or model, and when. Producing one requires an X.509 signing certificate whose chain validators trust; reading one takes a validator like c2patool or Adobe's Inspect tool. C2PA is the marking standard providers reach for when a regulation requires machine-readable disclosure of AI content — and the certificate half is the part 0byte runs for you. ### How do I get a C2PA certificate? Two ways. Buy an X.509 signing certificate from a certificate authority on the C2PA trust list and build the signing infrastructure around it, or sign through a managed service and skip that entirely. Certificate procurement is the single biggest C2PA adoption pain, and it's the part we run for you: manifests are signed with 0byte's managed credentials while your brand is named as the claim generator, so the credential reads “generated by you.” Bring-your-own-certificate is on the roadmap for teams that want it. ### Will the manifest validate in c2patool and C2PA-aware viewers? Yes — stamped files carry standard manifests that validate structurally in c2patool and other C2PA-aware tooling. Until 0byte's certificate completes the C2PA Conformance Program, validators note the signer isn't yet on the public trust list; the registry match independently proves origin in the meantime, and we disclose exactly that in our own verification. ### Is 0byte on the C2PA trust list? Not yet — our signing certificate is going through the C2PA Conformance Program. Until it completes, a validator reads a stamped file's manifest as structurally valid but flags that the signer isn't on the public trust list. In the meantime the registry fingerprint match establishes origin independently, and our own verification reports each signal separately rather than papering over the gap. If you need something to show an auditor today, the transparency log's inclusion proofs are the part that doesn't depend on trust-list status at all. Separately, every manifest is countersigned by an RFC 3161 timestamp authority, which fixes when the signature was made — so a signature stays checkable after the certificate that made it expires or is revoked, and a trust-list decision later still applies to files already published. The same caveat applies there for now: a validator notes the timestamp authority isn't trust-listed either, and we'd rather say that than let you find it in a report. We'll update this answer the day it changes. ### I already emit C2PA — why 0byte? Because your manifests don't survive the internet: most platforms strip metadata on upload. 0byte adds the soft binding the C2PA spec calls for — a fingerprint record outside the file — so origin stays recoverable after stripping, plus a free public verifier that satisfies the detection side of the new rules. One API covers marking and detection. ### What is a C2PA soft binding? A way of tying provenance to content that lives outside the file. Instead of relying on embedded metadata, a fingerprint is derived from what the content looks like and stored in a registry. A screenshot of a re-encoded copy still looks the same, so its fingerprint still matches — that's how the proof survives when embedded data is gone. It's the C2PA specification's own recovery mechanism; 0byte operates an open one. ### How is this different from SynthID or other watermarks? Watermarks alter pixels and cover one vendor's models. 0byte changes nothing about how your content looks, works for any model — including open-weights ones no watermark covers — and produces standard C2PA credentials any validator can read. When a C2PA manifest survives, verification reports it alongside the registry match — both signals, one call. We do not read vendor watermarks: SynthID and OpenAI's detectors are not publicly callable, so we do not claim to see them. ### What happens if content was never stamped? Verification says exactly that: no provenance found — no manifest, no registry match. It never converts absence of evidence into a guess about whether something is AI-generated. For teams that want a statistical signal, the API reserves an opt-in estimate (the deprecated /v1/analyze endpoint) — always separate from the verdict, clearly marked as an estimate, and when its model service is paused the response discloses that rather than guessing. ### Does 0byte satisfy Article 50, the Code of Practice, or SB 942? Those rules require machine-readable marking, reliable detection, and auditability. A stamp provides standard machine-readable marking (C2PA), the fingerprint registry keeps it detectable after platforms strip metadata, and the signed transparency log makes the record independently auditable. Whether your specific deployment satisfies a given obligation depends on your system — our docs map each requirement to each feature, and none of it is legal advice. ### What data does 0byte store? The fingerprint, who stamped it, the model name, a timestamp, and the digital signature. Never the content itself, never the prompt. The fingerprint is a compact perceptual hash — it mathematically cannot be reversed back into your image. Content sent to verification is checked in memory and never stored. That covers stamping and verifying. Separately, if you hold an account or write to us, we keep what you handed over — your account details, and anything you send through the waitlist or contact form. The privacy policy lists every category in one place. ### How much does C2PA signing cost? Verifying content is free forever — no account needed; a public registry only works if checking it costs nothing. Stamping has a free tier (60 calls per minute), with higher-throughput tiers for production. Pricing scales with usage, not seats. ### Why should I trust the registry? You don't have to trust us — you can check the math. The registry is an append-only Merkle transparency log, the same structure behind Certificate Transparency, which has secured HTTPS for over a decade. Every proof comes with an inclusion proof anyone can verify independently against an Ed25519-signed tree head, and the docs include a complete worked verifier. If anyone — including 0byte — tried to rewrite history, the published roots would stop adding up. ### Can 0byte be fooled? Heavily regenerating content through another AI model defeats any system that works from what content looks like — ours included, and every watermark and detector too. We say this openly because no honest provenance vendor can claim otherwise. That's why verification reports each signal separately with the evidence behind it, instead of pretending a single one is bulletproof. ### Which file formats support C2PA signing? Images today: PNG, JPEG, WebP, GIF, and TIFF get the full stamp — embedded Content Credentials plus the registry record; BMP and ICO fall back to registry-only, and the response always says which you got. Up to 10 MB per file. Audio and video are on the roadmap, and we won't claim them before they ship. Cropping is the hard case for any perceptual hash, so stamping registers the crops the internet predictably makes — the square, 4:5 and 16:9 feed crops, a trimmed border up to about a tenth, a chopped caption or UI bar — and verification reports which one matched. What doesn't match yet: deeper trims, an off-centre window, or a detail cut out of the middle. ## Compared with the alternatives - Works with / extends C2PA — C2PA alone: —; Watermarks: No; AI detectors: No; C2PA + 0byte: Yes — signs and validates standard manifests - Survives social media upload — C2PA alone: Usually stripped with the metadata; Watermarks: Mostly; AI detectors: n/a — guesses after the fact; C2PA + 0byte: Yes — the registry record remains - Survives screenshots & re-encoding — C2PA alone: No — the file is new; Watermarks: Mostly — resized crops weakest; AI detectors: n/a; C2PA + 0byte: Yes — the fingerprint still matches - Covers any AI model, including open-weights — C2PA alone: Any signing provider; Watermarks: Only participating models; AI detectors: Uneven on unseen generators; C2PA + 0byte: Yes — anyone can stamp - Certificate you must procure — C2PA alone: Yes — your own signing cert; Watermarks: n/a; AI detectors: n/a; C2PA + 0byte: No — signed for you, brand still named - What a match gives you — C2PA alone: Signed claim (when it survives); Watermarks: Vendor classifier score; AI detectors: A probability; C2PA + 0byte: Signed, logged record: declared provider, model, brand and time Heavy AI regeneration of content defeats every system on this table — 0byte included. We're the only column that says so out loud. ## Articles - AI watermarking is a signal, not a verdict — https://0byte.tech/blog/ai-watermarking-signal-not-verdict Google has watermarked over 10 billion pieces of content, and you still need a waitlist to check one. AI watermarking is strong when present, meaningless when absent, and readable by almost nobody — which makes it excellent evidence and a bad verdict. - Deepfake evidence reached court before the rules did — https://0byte.tech/blog/deepfake-evidence-before-the-rules A federal rule written for deepfakes already exists in draft. Its comment period closed in February 2026, and the committee declined to advance it in May. So synthetic evidence is still governed by rules written before generative models — which work, but only for a party with a record of origin. - The FBI put $893 million next to AI fraud — https://0byte.tech/blog/fbi-893-million-ai-fraud The FBI's 2025 report logged 22,364 AI-related complaints and $893 million in losses. In the one category it measured closely, the AI-flagged share was under 8% of the total — because victims could not tell. That gap is a verdict on detection, not an argument for more of it. - Election deepfake laws meet their first real election — https://0byte.tech/blog/election-deepfake-laws-first-real-test Thirty-one states now regulate election deepfakes, and the 2026 midterms are the first cycle to test all of them. The ads are already running — labeled, unlabeled, and in court. Disclosure outlived the outright bans. A disclosure rule only bites if someone can establish where a video came from. - Article 50 is live. Marking was the easy half. — https://0byte.tech/blog/article-50-marking-was-the-easy-half EU AI Act Article 50 applies from 2 August 2026, with 2 December for systems already on the market. It asks for two things: machine-readable marking and detectability. Everyone shipped the first. The second is where compliance breaks. - Valid is not trusted: how C2PA certificates really work — https://0byte.tech/blog/valid-is-not-trusted-c2pa-certificates A C2PA certificate is two things wearing one name: a keypair anyone can make, and a place on a trust list now gated behind security evaluation. Why c2patool says valid while validators say untrusted, and what to ship in the meantime. - Why provenance beats detection — https://0byte.tech/blog/why-provenance-beats-detection AI detectors output a probability, not a fact — and the false positives land on real people. Here is why recording where content came from beats guessing after the fact. - Where did this image come from? The question 2026 is forcing the internet to answer — https://0byte.tech/blog/where-did-this-image-come-from Phones now cryptographically sign photos, Chrome and Search verify them, and EU law soon requires AI content to be detectable. Origin is becoming a first-class property of every image — here's what's driving it, and where the current approach still breaks. - Content Credentials solve half the problem — https://0byte.tech/blog/content-credentials-solve-half-the-problem C2PA is the most important standard in content provenance, and you should use it. It also leaves one half of the problem open — the half where content actually travels. - A record you can't rewrite — https://0byte.tech/blog/a-record-you-cant-rewrite A signature proves who signed something. It does not prove when, or that nobody swapped it since. For proof of origin, that gap is everything — and it is what a transparency log closes. - How a fingerprint survives what the file cannot — https://0byte.tech/blog/how-a-fingerprint-survives A screenshot changes every byte of an image while your eye sees the same picture. Perceptual fingerprinting is the trick that closes that gap — here is how it actually works. ## Contact - Contact form: https://0byte.tech/contact - Email: sidhanth@0byte.tech - GitHub: https://github.com/0byte-lab - X: https://x.com/0byteHQ Attribution: cite as "0byte" with a link to https://0byte.tech/.