# Thumbprints

A thumbprint, also known as a fingerprint or simply a hash, is a secure hash digests of a DiME item or envelope. These are generated by using a secure hash algorithm on the DiME encoded string of an envelope or item.

Thumbprints makes it possible to generate and store a thumbprint of an item, and then re-generate the thumbprint later to understand if an item is the same or if it has changed, all without the need for additional decoding or, depending on the thumbprint scope, signature verification.

Thumbprints are never not stored within a DiME envelope or item, as they should be re-generated when needed. An exception to this is when using [item links](/cryptography/item-links.md).

By using the following DiME item:

{% code overflow="wrap" %}

```
Di:KEY.eyJjYXAiOlsiZW5jcnlwdCJdLCJpYXQiOiIyMDIyLTEwLTIyVDEyOjI4OjA1LjA0MTI4NVoiLCJrZXkiOiJTVE4uQm1XRnFVVGRZcE1uNVRESkc2NEd5dDVMcm9XTnV0WnNHMmE4RFBIVFk4WGRleU5aayIsInVpZCI6IjZiOGY5NTM2LTljOGUtNDA2NC05NTdhLTM1MjJmNmMzYTkzZiJ9
```

{% endcode %}

… the following thumbprint is generated:

```
f31eecac1bf624d811e3bd09e3da87814b159fbc2b22eaeaf20e50919b373779
```

The above example is using the DiME standard cryptographic suite when generating the thumbprint and it then encoded as HEXADECIMAL.


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