# Initiate Registration

To register a user with Passkeys using the API you first need to make sure you have the values for your request headers set up by following the [unauthenticated-requests](https://docs.0xpass.io/appendix/api-request-setup/unauthenticated-requests "mention") setup guide.

Once you have your values for `x-scope-id` and `x-encrypted-key` setup. You can now initiate a user registration. 

The initiateRegistration method initiates the user registration process within a specific scope. It generates a registration challenge that the user must solve to proceed with their registration. 

### **HTTP Method**: POST

* [Headers](https://docs.0xpass.io/appendix/api-request-setup/unauthenticated-requests)
  * X-Scope-Id: A UUID string representing the application scope.
  * X-Encrypted-Key: A string containing the encrypted key for secure communication.
* **Body**:
  * **encrypted\_user**: String - A base64-encoded string containing encrypted user data.

The `encrypted_user` is generated by RSA encrypting the user parameters with the non-encrypted AES key you generated when following [unauthenticated-requests](https://docs.0xpass.io/appendix/api-request-setup/unauthenticated-requests "mention"), and by using the following `aesEncrypt` function.

```typescript
const aesEncrypt = async (
  plainText: string,
  encryptionKey: BufferSource,
  keyFormat: "raw" = "raw",
  keyLength: number = 256
) => {
  if (!encryptionKey) {
    throw Error("Encryption key not initialized");
  }

  const encoder = new TextEncoder();
  const data = encoder.encode(plainText);
  let cryptoKey: CryptoKey;
  let encrypted: ArrayBuffer;

  try {
    cryptoKey = await importKey(keyFormat, encryptionKey, { name: "AES-GCM", length: keyLength }, [
      "encrypt",
    ]);

    const iv = cryptoObj.getRandomValues(new Uint8Array(12)); // Initialization vector
    
    // Same encrypt function from "Unauthenticated Requests" guide.
    encrypted = await encrypt({ name: "AES-GCM", iv }, cryptoKey, data);

    const combined = new Uint8Array(iv.length + encrypted.byteLength);
    combined.set(iv, 0);
    combined.set(new Uint8Array(encrypted), iv.length);

    return btoa(String.fromCharCode.apply(null, combined));
  } catch (error) {
    console.error("AES-GCM Encryption error:", error);
    throw error;
  }
};
```

Now we can encrypt our user parameters and pass that value as our `encrypted_user` in our API request.

```typescript
const params = {
    username: "test_user",
    userDisplayName: "test_user"
}

// Same aesKey created with `generateAesKey`
const encrypted_user = await aesEncrypt(JSON.stringify(params), aesKey);
```

### Response Spec

* **challenge\_id**: String - A UUID that uniquely identifies the registration challenge.
* **encrypted\_creation\_challenge**: String - A base64-encoded string representing the encrypted challenge that the user must solve to proceed with registration.

### Request Example

```http
POST / HTTP/1.1
Host: tiramisu.0xpass.io
Content-Type: application/json
x-scope-id: 123e4567-e89b-12d3-a456-426614174000
x-encrypted-key: jp6t2GVOvzltN+4VGc21ZKPIbLjEvitE34cFYDvVNrcmF2ukcKMTO8R/F0wbonGZM0NZBg2X94FvirH6Hi2U1zFlXN5srkOdvQL3lVNZ86gbfEtJFPOEAeZkxtTOKOsH4ZXPtUbFOjT2Niblo8njOKibOoAMRKIhtsNTTvRXjHRxnNqVs3QcSe7XbO1DbH/pdRgq+YZN13znlSRsupu4G/h/KBEZr98wXFo8PeDV9F8ZV56F90GqQ3wKzFUBwC9rJihGz0omH+eJA0jB/K7BYt30fhWDnqaLNP2eb1mbIjBCmv6sXqu2jtghr3ejl0YwjP9lCO+aVD7bophfb/IyKg==

{
    "jsonrpc": "2.0",
    "method": "initiateRegistration",
    "params": {
        "encrypted_user": "JZVjZw33OGoQDEMcbOdckx4TzspQEKP5j+iAGqf6b6gPleziY/Noyd4uW6KMSujq0HKP2Rb69p9Wi8ic5O8LZl9oTmmWk4op0CUKejqcV5DsNDp83PYzUg=="
    },
    "id": 1
}
```

### Response Example

```json
{
    "jsonrpc": "2.0",
    "result": {
        "challenge_id": "e0f8cbee-6d64-4a9b-af88-3d73a8b95b34",
        "encrypted_creation_challenge": "JZVjZw33OGoQDEMcbOdckx4TzspQEKP5j+iAGqf6b6gPleziY/Noyd4uW6KMSujq0HKP2Rb69p9Wi8ic5O8LZl9oTmmWk4op0CUKejqcV5DsNDp83PYzUg=="
    },
    "id": 1
}
```