---
title: Generating JWS impressions
framework: adattributionkit
role: article
role_heading: Article
path: adattributionkit/generating-jws-impressions
---

# Generating JWS impressions

Create a JSON Web Signature (JWS) for use with app impressions in AdAttributionKit.

## Overview

Overview A JSON Web Signature (JWS) is an open standard (RFC 7515) that defines a way to securely transmit information. AdAttributionKit requires a JWS to create an AppImpression. You create the JWS and sign it with your private key. For more information about creating keys, see Registering an ad network To generate a signed compact JWS: Create the JOSE (JSON Object Signing and Encryption) header. Create the JWS payload. Sign the JWS. Create the JOSE header To create a JWS impression to use with AdAttributionKit, use the following fields and values in the header:  |   |   |  Here’s an example of a JOSE header:     {         "alg": "ES256",         "kid": "example.adattributionkit"     } Create the JWS payload The JWS payload contains information about the advertisement, such as the advertised app item ID, publisher app item ID, source identifier, and type of impression. Use the following fields to include these values in the JWS payload:  |   |   |   |   |   |   |   |   |  Here’s an example of a JWS payload: {  "impression-identifier": "7aa9f8cc-5689-4c02-b963-22ca22136015",  "publisher-item-identifier": 0,  "impression-type": "app-impression",  "ad-network-identifier": "example.adattributionkit",  "source-identifier": 5239,  "timestamp": 1679790422446,  "advertised-item-identifier": 1108187390 } To create impressions eligible for reengagement conversions, add the following field and value to the JWS payload: {     // Other payload properties.     "eligible-for-re-engagement": true } Sign the JWS Use the private key you generated during ad network registration to sign the JWS using ES256 encryption. You need to sign the JWS in the compact format outlined in section 5.1 of RFC 7515 that describes the JWS signature process and format, and conforms to the following format as a UTF-8 string: ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)) This renders a compact JWS impression like the example below that you can pass into the API: eyJraWQiOiJleGFtcGxlLmFkYXR0cmlidXRpb25raXQiLCJhbGciOiJFUzI1NiJ9.eyJhZHZlcnRpc2VkLWl0ZW0taWRlbnRpZmllciI6MTEwODE4NzM5MCwiYWQtbmV0d29yay1pZGVudGlmaWVyIjoiZXhhbXBsZS5hZGF0dHJpYnV0aW9ua2l0IiwiaW1wcmVzc2lvbi10eXBlIjoiYXBwLWltcHJlc3Npb24iLCJlbGlnaWJsZS1mb3ItcmUtZW5nYWdlbWVudCI6dHJ1ZSwidGltZXN0YW1wIjoxNzE5NTk5OTU3MjM5LCJwdWJsaXNoZXItaXRlbS1pZGVudGlmaWVyIjo1ODM4NDkyLCJpbXByZXNzaW9uLWlkZW50aWZpZXIiOiI1NDRCOEZBRC0wQUQ1LTQ0MzQtOThCMi0zMjcxMTNBRjg0REIiLCJzb3VyY2UtaWRlbnRpZmllciI6NTIzOX0.zxQ_HcpB7pK6lWOms4LZ8uK3sZu_0S-bPR0My7UY4QlEAYFP-wp5eN1WuHOmNwoPD5cgazpwA3o5xq-fhfpOEQ