> ## Documentation Index
> Fetch the complete documentation index at: https://developers.authlete.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Generating Encrypted ID Tokens

> Generating encrypted ID tokens for a particular client using Authlete and registering a JWK set for encryption.

## Preface

This article describes an example on how to configure Authlete to generate encrypted ID tokens for a particular client.

***

## Preparing and registering a JWK set

Prepare and register a JWK set to be used for encrypting ID tokens. See the following article for instructions.

* [JWK Set Settings for OAuth / OIDC Client](/configuration-reference/key-management/jwk-set-settings-for-an-oauth-oidc-client)

In this example, the following JWK set is registered.

```
{
    "keys": [
        {
            "kty": "EC",
            "use": "enc",
            "crv": "P-256",
            "kid": "_agec7UaYVN4c3RZQJQhUuR6nFSnqEXywv3QaIfFRFk",
            "x": "ilLNQ-Lcp_t5DBs9puJVI3JhwqlMndTILjkBrNd3Dsc",
            "y": "3Uy7NIHilkOWviGXMRIl2ZUE4L7Mc8ub4VhosE3l8t8"
        }
    ]
}
```

![](https://files.timelapsehc.com/attachments/attachment/5e4d2884-97c4-41b0-b4f9-fed3a5b18ee1/image.png)

***

## Configuring ID token encryption

Choose encryption algorithm of ID token for the client. See [Client Settings - JWK Set](/configuration-reference/key-management/jwk-set-settings-for-an-oauth-oidc-client)
for details.

In this example, the following settings in accordance with the registered public key are specified:

| Item                                   | Value              |
| -------------------------------------- | ------------------ |
| ID Token Encryption Algorithm          | **ECDH\_ES**       |
| ID Token Encryption Encoding Algorithm | **A128CBC\_HS256** |

<img src="https://mintcdn.com/authlete/EJDZNZMvOu_9CJHJ/configuration-reference/tokens-and-claims/encrypted-id-token_1.png?fit=max&auto=format&n=EJDZNZMvOu_9CJHJ&q=85&s=8cd10fde1556e42d9e5a2ded0fb4ef12" alt="encrypted-id-token_1" width="940" height="743" data-path="configuration-reference/tokens-and-claims/encrypted-id-token_1.png" />

*Settings for ID token encryption*

***

## Generating an encrypted ID token

With the settings above, Authlete will be encrypting ID tokens for the client, like the following value:

```
eyJlcGsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOiJDeVU3XzdMNlRaeHdmZzhBNkRUNUxMSz
1ZWlBSE1yTzJyYWt5WEY0TUFZIiwieSI6InZ6MkJZd1k1WmJFUkV2OGxTcWNuREpQVkdQMExyWXpUS2NiZUR2aTVKQlUifSw
ia2lkIjoiX2FnZWM3VWFZVk40YzNSWlFKUWhVdVI2bkZTbnFFWHl3djNRYUlmRlJGayIsImVuYyI6IkExMjhDQkMtSFMyNTY
iLCJhbGciOiJFQ0RILUVTIn0..e9rmLbmTkuaUL7AdUB9umw.-o4aia0O6FUarqN3Owssu6ko4v9YqjMJXm00Sj-w7oH7YjmgZDR
j7omoXSnmU19wYFhC70yzv8U2B0pXNxLqVZOv4vQchwslP6Ms55cmgvenCHcIbsXFirb8we-6Z0EfKiKmLCy0NU8kFE0fQ-6y9
n91WI9hGPVbw968FtA2y7x2JXGv93nPryshCp4HJz2HXQeb5F18RSsCAkY5nE7-GqD81DnmG6-rdVoOBAGM7LK_lc8gIhSozmNn7
8cFtfQrNn6S0VFWM2e8SyukQtdGk3um3mZAjRdDNtsACkztQJo.5S7YimrpLKuWnRM0hwdJzweyJlcGsiOnsia3R5IjoiRUMiLCJj
cnYiOiJQLTI1NiIsIngiOiIzUHNVT0lj
```

***

## Decrypting the ID token

On receiving the ID token above, the client will be decrypting it using the client's private key. The following is a sample JWK set for the decryption:

```
{
    "Keys": [
        {
            "kty": "EC",
            "d": "4AEnTq3H8gcIutIoJCCZuv9GgWdKRaoJIXQkdM8r0UA",
            "use": "enc",
            "crv": "P-256",
            "kid": "_agec7UaYVN4c3RZQJQhUuR6nFSnqEXywv3QaIfFRFk",
            "x": "ilLNQ-Lcp_t5DBs9puJVI3JhwqlMndTILjkBrNd3Dsc",
            "y": "3Uy7NIHilkOWviGXMRIl2ZUE4L7Mc8ub4VhosE3l8t8",
            "typ": "ECDH_ES"
        }
    ]
}
```

Here is an example using [José](https://github.com/latchset/jose) to decrypt and other commands to extract a payload part:

```
jose jwe dec -i <ID token> -k <JWK set> \
| cut -d"." -f2 \
| base64 --decode \
| jq

{
  "sub": "testuser01",
  "aud": [
      "17201083166161"
  ],
  "iss": "https://authlete.com",
  "exp": 1595921860,
  "iat": 1595835460
}
```