试点·C2PA 审核中 · 韩国 2027.03 · 日本 2027.06 · 模范法为韩国法
版权 C-2026-036487 · 专利申请 10-2026-0100026（尚未注册）
Learn C2PA, step by step
C2PA is the international standard that tells you where a photo or video came from. You learn it in 10 chapters: each one gives a plain explanation, then something you try yourself on this site.
The 10-chapter course
The course comes in four parts. Open a chapter to see its explanation and practice.
Learn
Chapters 1–3 · get the ideas- Chapter 1
What is C2PA, and why do we need it?
How can you tell where a file came from?No sign-in neededDoneOpen this chapter - Chapter 2
File fingerprints (hashes) and practice certificates
Why does the fingerprint change when a file changes?No sign-in neededDoneOpen this chapter - Chapter 3
Five layers of stamps that protect the source
Why use five layers of stamps and not just one?Some steps need sign-inDoneOpen this chapter
- Chapter 1
Try
Chapters 4–6 · practice in a safe setting- Chapter 4
A signature tells you who made it
How does a digital signature prove “who”?Some steps need sign-inDoneOpen this chapter - Chapter 5
Trust links together like a chain
How can you trust the person who signed?Some steps with your mentorDoneOpen this chapter - Chapter 6
The stamp you see and the stamp you don't
If you shrink or re-save a photo, does the stamp stay?Some steps with your mentorDoneOpen this chapter
- Chapter 4
Issue
Chapter 7 · your mentor demonstrates a real issuanceCheck
Chapters 8–10 · check and sum up- Chapter 8
How other people check your file
What can a third party check, and what can't they?Some steps with your mentorDoneOpen this chapter - Chapter 9
Getting onto the international official list
What more is needed to go from a pilot to an official listing?Some steps with your mentorDoneOpen this chapter - Chapter 10
Improvement ideas and honest notices
How do you tell people about trust information without overstating it?Some steps with your mentorDoneOpen this chapter
- Chapter 8
Each chapter uses what the one before it taught. That is why it is easiest to go in order, starting at chapter 1.
Intro film
Read the film as text
- Here is one photo. Who made it, when, and with which tool?
- A file has a fingerprint, called a hash. Change one spot and the hash changes completely. 63 of 64 characters changed.
- Five layers protect the source: hidden mark, trace mark, fingerprint, C2PA credential, archive.
- A signature tells you who made it. A trust chain tells you whether you can trust that signer.
- Shrink or re-save a photo, and some marks stay while others disappear. The hash changes, the C2PA credential is often removed, a hidden mark can weaken, and a fingerprint (look-alike) stays similar.
- A practice (SAMPLE) certificate is not a real one. A technical score of A+ is not an official certification.
- When you check a file for someone else, say what was confirmed and what was not. Confirmed: the signer, and no change since signing. Not confirmed: whether the scene is true, and what happened before signing.
- The 10-chapter C2PA practice course. Start with chapter 1.
Four things worth knowing first
Each chapter explains the hard words one at a time. Here you just see the big picture.
C2PA is a shipping label for a file
It says who made the file, when, and with which tool. It does not promise that the content is true.Learn it in chapter 1Manifest = ingredients label
That record (the manifest) travels inside the file. If the file changes even a little, its fingerprint (hash) changes, and that shows.Learn it in chapter 2A signature is a personal seal plus a tamper tape
It shows who stamped it, and tearing it shows. But a real seal does not make the content true.Learn it in chapter 4Checking is like a receipt-number lookup
Anyone who receives a file can check it without signing in. It tells you only whether there is an issuance record and whether the file is unchanged.Learn it in chapter 8
This site's pilot certificate is not on the international official trust list (the C2PA Trust List) yet, so other checking tools may show the signature as untrusted. Chapters 7 and 9 explain the difference.
Using it in a company or team
Companies or teams that want to put C2PA signatures in their products apply for a certificate. In the Korea and Japan pilot, nothing is issued instantly: a person at the registration authority (RA) reviews the request first. Production service is planned for March 2027 in Korea and June 2027 in Japan.
More to read
- GuidesShort reads on provenance records.
- Provenance labTry watermark, fingerprint and C2PA checks on sample media.
- When it doesn't workAn honest list of cases where provenance records do not hold.
- DevelopersThe certificate API guide and its OpenAPI 3.1 document.
- Generate a CSRMake a certificate request (CSR). The private key stays on your computer.
For experts: the five layers of protection (XMSE)
When a file passes through messaging apps or social media, its C2PA record can be wiped. That is why this site protects provenance in five layers. Chapter 3 goes through them one by one.
- Hidden markinvisible watermark
- Trace markforensic mark
- File fingerprintlook-alike fingerprint
- C2PA credentialrecord + signature
- Archiveclosed hash chain
C1/C2 and C1b (the internal ledger) are records this site operates. C3 is a public timestamp from an external time-stamping authority (TSA). Bitcoin is not used.
When several people collude and mix files together, tracing gets harder. When the evidence is not certain, no one is named.
Chapter 1 needs no sign-in, so you can start right away. If you have a file at hand, you can also check it first.