# Verify an Object

The **vBase Verify** tool checks whether a file—or its content ID (SHA3 hash)—has previously been stamped on the blockchain using vBase. If a match is found, the app displays the full stamp details, including the timestamp, blockchain address, and other stamp details.

## How to Verify a Stamp

For a quick overview, [🎥 Watch the How-To Video](https://youtu.be/nzbC3UphfGM)

#### Step-by-Step Instructions

1. Visit [vBase Verify](https://app.vbase.com/verify)
2. Select the file you want to verify
3. The app calculates the file’s content ID ([SHA3 hash](https://csrc.nist.gov/publications/detail/fips/202/final)) in your browser
4. It queries the blockchain (currently [Polygon](https://polygon.technology/)) for any stamp matching that content ID
5. If a match is found, full stamp details are displayed

## What Happens Behind the Scenes

When you verify a file:

1. The **SHA3 hash** (also called the content ID or digital fingerprint) is calculated **locally in your browser**
2. vBase uses this content ID to search for matching stamp transactions on the relevant blockchains (currently Polygon)
3. If a match is found, the app retrieves and displays the following **on-chain stamp metadata**:

   | 🔗 Data Type              | Description                                                                     |
   | ------------------------- | ------------------------------------------------------------------------------- |
   | 📅 **Timestamp**          | When the stamp was recorded on-chain                                            |
   | 👤 **Blockchain Address** | The blockchain address associated with the vBase account that created the stamp |
   | 🧩 **Content ID**         | A hash (unique fingerprint) of the file                                         |
   | 🗂️ **Collection ID**     | A hash of the name of the collection to which the file belongs (if applicable)  |
   | 🔗 **Transaction Hash**   | Blockchain transaction ID for the stamp                                         |

> 💡 This information is pulled directly from the blockchain and is independently verifiable.

In some cases, **off-chain metadata** from the vBase database (e.g., **Username**, **Collection Name**, **Identity Verification Status**) may also be shown if available.

<figure><img src="https://4101148087-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fq4MLOHYMJWnZwBvFYFky%2Fuploads%2Fgit-blob-f6c90db7ec2e0f4eb2fec69965afc57d3fb94870%2FExample_VerifyStamp_Output.png?alt=media" alt="" width="500"><figcaption><p>Example of vBase Verify Output</p></figcaption></figure>

> **User Notes**
>
> * Your file’s hash is always calculated **locally in your browser**
> * The file itself is **never uploaded** or seen by vBase during verification
> * All stamps are currently recorded on the Polygon blockchain and are independently verifiable
> * Advanced users can query stamps directly via tools like [Dune](https://dune.com/), [Polygonscan](https://polygonscan.com/), or publicly available Polygon nodes<br>

## Frequently Asked Questions

#### What If My File Doesn’t Match?

Even a **1-character or 1-byte change** to a file will produce a completely different content ID.

This means:

* The file must match **exactly**—bit-for-bit—with the originally stamped version
* If you've re-saved, edited, or reformatted the file in any way, the hash will not match
* You can calculate the SHA3 hash locally using tools like `sha3sum`, `openssl`, or browser-based hash calculators to compare with the content ID. A few public calculators are available [here](https://emn178.github.io/online-tools/sha3_256_checksum.html) and [here](https://www.browserling.com/tools/sha3-hash).

#### Can I Verify a Content ID Without Loading a File?

Yes! If you already know your file’s **SHA3 hash**, you can paste it into the **"Verify by Content ID"** field:

1. Go to [vBase Verify](https://app.vbase.com/verify/?method=hash)
2. Click **"Verify by Hash"**
3. Paste the SHA3 hash (hex format, e.g., `0xabc123...`)
4. The app will search for a match and display any corresponding stamp

#### How Are Collections Handled?

If the file was originally stamped as part of a **Collection**, the Verify app will:

* Display the **Collection ID** associated with the file
* Show the **Collection Name**, if available

> 📌 This is especially useful when verifying which files belong to specific projects, datasets, or deliverables.

#### Can multiple people stamp the same file?

Yes. If a user stamps the same file twice or two users stamp an identical file, it will produce the same content ID. The blockchain will show multiple transactions for that content ID, each with its own timestamp and blockchain address. For real-world data with any reasonable amount of entropy, this is extremely unlikely.

#### Is there an API for verification?

Yes, see the Python SDK samples for verifying via the API.

#### What happens if a stamp is deleted from vBase?

Stamp records on the **blockchain are permanent**. If the original copy of the file is lost, then the associated Stamp will not be verifiable, however it will still be visible on-chain.

## Glossary

| Term               | Meaning                                           |
| ------------------ | ------------------------------------------------- |
| **SHA3 Hash**      | A unique fingerprint for a file                   |
| **Content ID**     | A vBase-specific name for an object's fingerprint |
| **On-chain Data**  | Info permanently stored on the blockchain         |
| **Off-chain Data** | Extra metadata, not on the blockchain             |

## Need Help?

* 📖 [How to Stamp a File](https://docs.vbase.com/web-tools/how-to-use-vbase-stamper)
* 🧩 [What Is a SHA3 Hash?](https://en.wikipedia.org/wiki/SHA-3)