# Create a Subject DID

In decentralized identity systems, **Holders** (also referred to as **Subjects**) are the recipients of **Verifiable Credentials**—typically representing individuals, organisations, objects or devices.

To enable credential interactions such as **receiving**, **presenting**, and **proving control** over an identity, each Holder needs a unique cryptographic key pair. This key pair is used to create a **Decentralized Identifier (DID)** that represents their identity.

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## Use Cases for Holder Identity Keys

After generating a key pair using the API below, you can use it to:

* ✅ **Generate a `did:key` identifier**, an off-ledger, self-contained DID that is ideal for lightweight identity use cases

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## Why Use `did:key` for Holders?

The `did:key` method is a simple, deterministic DID method that embeds the Holder’s public key directly into the DID itself. It doesn’t require blockchain anchoring, making it:

* ⚡ **Fast and lightweight** – no on-ledger operations required
* 🔐 **Privacy-preserving** – good for ephemeral or throwaway identifiers
* 🧪 **Useful for testing and interoperability** – widely supported by wallets and agent frameworks
* 🧍 **Ideal for Holder/Subject identities** – where the main role is to receive and present credentials rather than issue them

Many ecosystems choose `did:key` for **wallet-based identities**, while keeping issuer DIDs on-ledger (e.g. `did:cheqd`) to ensure resolvability and public trust.

Take a deeper look into the `did:key` specification here:

<table data-card-size="large" data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><mark style="color:blue;"><strong>Create a  did:key DID</strong></mark></td><td>Create an off-ledger 'holder' or 'subject' DID, of the <code>did:key</code> method using the specification.</td><td><a href="https://w3c-ccg.github.io/did-key-spec/">https://w3c-ccg.github.io/did-key-spec/</a></td></tr></tbody></table>

{% hint style="success" %}
Note that there are also perfectly valid use cases for using a `did:cheqd` DID for a 'Holder' or 'Subject' DID as well, where it is valuable to have the 'Holder' / 'Subject' identifiable on-chain.&#x20;

For example, AI Agents, Organisations or products in a supply chain are good use cases for using `did:cheqd`. &#x20;

This is because the 'Holder' / 'Subject' does not have Personally Identifiable Information (PII) associated with it.
{% endhint %}

***

## Get Started

To create a `did:key` DID, you can generate an identity key pair using the API below on cheqd Studio.

## Create an identity key pair.

> This endpoint creates an identity key pair associated with the user's account for custodian-mode clients.

```json
{"openapi":"3.0.0","info":{"title":"cheqd Studio API for cheqd network","version":"2.0.0"},"tags":[{"name":"Keys"}],"servers":[{"url":"https://studio-api.cheqd.net","description":"Main (production) server"},{"url":"https://studio-api-staging.cheqd.net","description":"Staging server for testing"},{"url":"http://localhost:3000","description":"Local server for testing"}],"security":[{"ApiKeyAuth":[]}],"components":{"securitySchemes":{"ApiKeyAuth":{"type":"apiKey","name":"x-api-key","in":"header"}},"schemas":{"KeyResult":{"type":"object","properties":{"kid":{"type":"string"},"type":{"type":"string","enum":["Ed25519","Secp256k1"]},"publicKeyHex":{"type":"string"}}},"InvalidRequest":{"description":"A problem with the input fields has occurred. Additional state information plus metadata may be available in the response body.","type":"object","properties":{"error":{"type":"string"}}},"UnauthorizedError":{"description":"Access token is missing or invalid","type":"object","properties":{"error":{"type":"string"}}}}},"paths":{"/key/create":{"post":{"tags":["Keys"],"summary":"Create an identity key pair.","description":"This endpoint creates an identity key pair associated with the user's account for custodian-mode clients.","parameters":[{"name":"type","description":"Key type of the identity key pair to create.","in":"query","schema":{"type":"string","enum":["Ed25519"]}}],"responses":{"200":{"description":"The request was successful.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/KeyResult"}}}},"400":{"description":"A problem with the input fields has occurred. Additional state information plus metadata may be available in the response body.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/InvalidRequest"}}}},"401":{"$ref":"#/components/schemas/UnauthorizedError"},"500":{"description":"An internal error has occurred. Additional state information plus metadata may be available in the response body.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/InvalidRequest"}}}}}}}}}
```