UID2 SDK for Java Reference Guide

You can use the UID2 SDK for Java on the server side to facilitate the following:

• Generating UID2 advertising tokens
• Refreshing UID2 advertising tokens
• Encrypting raw UID2s to create UID2 tokens for sharing
• Decrypting UID2 tokens to access the raw UID2s
• Mapping DII to raw UID2s

Functionality

This SDK simplifies integration with UID2 for any publishers, DSPs, advertisers, data providers, and UID2 sharers who are using Java for their server-side coding. The following table shows the functions it supports.

Encrypt Raw UID2 to UID2 Token	Decrypt UID2 Token	Generate UID2 Token from DII	Refresh UID2 Token	Map DII to a Raw UID2
Supported	Supported	Supported	Supported	Supported

API Permissions

To use this SDK, you'll need to complete the UID2 account setup by following the steps described in the Account Setup page.

You'll be granted permission to use specific functions offered by the SDK, and given credentials for that access. Bear in mind that there might be functions in the SDK that you don't have permission to use. For example, publishers get a specific API permission to generate and refresh tokens, but the SDK might support other activities that require a different API permission.

For details, see API Permissions.

Version

The SDK requires Java version 1.8 or later.

GitHub Repository/Binary

This SDK is in the following open-source GitHub repository:

• UID2 SDK for Java

The binary is published on the Maven repository:

• https://central.sonatype.com/artifact/com.uid2/uid2-client

Initialization

The initialization step depends on the role, as shown in the following table.

Role	Create Instance of Class	Link to Instructions
Publisher	PublisherUid2Client	Usage for Publishers
Advertiser/Data Provider	IdentityMapClient	Usage for Advertisers/Data Providers
DSP	BidstreamClient	Usage for DSPs
Sharer	SharingClient	Usage for UID2 Sharers

You will need to provide the values necessary for the SDK to authenticate with the UID2 service.

Parameter	Description
baseUrl/uid2BaseUrl	The endpoint for the UID2 service. See Environments.
clientApiKey	The API key. See UID2 Credentials.
base64SecretKey	The client secret. See UID2 Credentials.

Interface

The BidstreamClient class allows you to decrypt UID2 tokens into raw UID2s. For details on the bidding logic for handling user opt-outs, see DSP Integration Guide.

The SharingClient class allows you to encrypt raw UID2s into UID2 tokens and decrypt UID2 tokens into raw UID2s.

note

When you use an SDK, you do not need to store or manage decryption keys.

Encryption Response Content

When encrypting with the SharingClient class, the SDK returns the information shown in the following table.

Method	Description
getStatus()	The encryption result status. For a list of possible values and definitions, see Encryption Response Statuses.
getEncryptedData()	The encrypted UID2 token.

Encryption Response Statuses

Encryption response codes, and their meanings, are shown in the following table.

Value	Description
SUCCESS	The raw UID2 was successfully encrypted and a UID2 token was returned.
NOT_AUTHORIZED_FOR_KEY	The requester does not have authorization to use the encryption key.
NOT_AUTHORIZED_FOR_MASTER_KEY	The requester does not have authorization to use the master key.
NOT_INITIALIZED	The client library is waiting to be initialized.
KEYS_NOT_SYNCED	The client has failed to synchronize keys from the UID2 service.
ENCRYPTION_FAILURE	A generic encryption failure occurred.

Decryption Response Content

Whether decrypting with the BidstreamClient class or the SharingClient class, the SDK returns the information shown in the following table.

Methods	Description
getStatus()	The decryption result status. For a list of possible values and definitions, see Decryption Response Statuses.
getSiteId()	The raw UID2 for the corresponding UID2 token.
getEstablished()	The timestamp indicating when a user first established the UID2 with the publisher.

Decryption Response Statuses

Decryption response codes, and their meanings, are shown in the following table.

Value	Description
SUCCESS	The UID2 token was decrypted successfully and a raw UID2 was returned.
NOT_AUTHORIZED_FOR_KEY	The requester does not have authorization to decrypt this UID2 token.
NOT_INITIALIZED	The client library is waiting to be initialized.
INVALID_PAYLOAD	The incoming UID2 token is not a valid payload.
EXPIRED_TOKEN	The incoming UID2 token has expired.
KEYS_NOT_SYNCED	The client has failed to synchronize keys from the UID2 service.
VERSION_NOT_SUPPORTED	The client library does not support the version of the encrypted token.
INVALID_TOKEN_LIFETIME	The token has an invalid timestamp.

Usage for Publishers

As a publisher, there are two ways to use the UID2 SDK for Java:

1. Basic Usage is for publishers who want to use this SDK's HTTP implementation (synchronous OkHttp).
2. Advanced Usage is for publishers who prefer to use their own HTTP library.

For an example application that demonstrates both Basic and Advanced usage, see Java UID2 Integration Example.

Basic Usage

If you're using the SDK's HTTP implementation, follow these steps.

1. Create an instance of PublisherUid2Client as an instance variable:

   private final PublisherUid2Client publisherUid2Client = new PublisherUid2Client(UID2_BASE_URL, UID2_API_KEY, UID2_SECRET_KEY);

2. Call a function that takes the user's email address or phone number as input and generates a TokenGenerateResponse object. The following example uses an email address:

   TokenGenerateResponse tokenGenerateResponse = publisherUid2Client.generateTokenResponse(TokenGenerateInput.fromEmail(emailAddress).doNotGenerateTokensForOptedOut());
   important

   Always apply doNotGenerateTokensForOptedOut(). This applies a parameter similar to setting optout_check=1 in the call to the POST /token/generate endpoint (see Unencrypted JSON Body Parameters).

Client-Server Integration

If you're using client-server integration (see Client-Server Integration Guide for JavaScript), follow this step:

• Send this identity as a JSON string back to the client (to use in the identity field), using the following:

  tokenGenerateResponse.getIdentityJsonString()
  note

  If the user has opted out, this method returns null, so be sure to handle that case.

Server-Side Integration

If you're using server-side integration (see Publisher Integration Guide, Server-Side), follow these steps:

1. Store this identity as a JSON string in the user's session, using the tokenGenerateResponse.getIdentityJsonString() function.

   If the user has opted out, this method returns null, so be sure to handle that case.

2. To retrieve the user's UID2 token, use the following:

   IdentityTokens identity = tokenGenerateResponse.getIdentity();
   if (identity != null) { String advertisingToken = identity.getAdvertisingToken(); }

3. When the user accesses another page, or on a timer, determine whether a refresh is needed:

   1. Retrieve the identity JSON string from the user's session, and then call the following function that takes the identity information as input and generates an IdentityTokens object:

      IdentityTokens identity = IdentityTokens.fromJsonString(identityJsonString);

   2. Determine if the identity can be refreshed (that is, the refresh token hasn't expired):

      if (identity == null || !identity.isRefreshable()) { we must no longer use this identity (for example, remove this identity from the user's session) }

   3. Determine if a refresh is needed:

      if (identity.isDueForRefresh()) {..}

4. If needed, refresh the token and associated values:

   TokenRefreshResponse tokenRefreshResponse = publisherUid2Client.refreshToken(identity);

5. Store tokenRefreshResponse.getIdentityJsonString() in the user's session.

   If the user has opted out, this method returns null, indicating that the user's identity should be removed from the session. To confirm optout, you can use the tokenRefreshResponse.isOptout() function.

Advanced Usage

1. Create an instance of PublisherUid2Helper as an instance variable:

   private final PublisherUid2Helper publisherUid2Helper = new PublisherUid2Helper(UID2_SECRET_KEY);

2. Call a function that takes the user's email address or phone number as input and creates a secure request data envelope. See Encrypting requests. The following example uses an email address:

   EnvelopeV2 envelope = publisherUid2Helper.createEnvelopeForTokenGenerateRequest(TokenGenerateInput.fromEmail(emailAddress).doNotGenerateTokensForOptedOut());

3. Using an HTTP client library of your choice, post this envelope to the POST token/generate endpoint, including headers and body:

   1. Headers: Depending on your HTTP library, this might look something like the following:

      .putHeader("Authorization", "Bearer " + UID2_API_KEY)
.putHeader("X-UID2-Client-Version", PublisherUid2Helper.getVersionHeader())

   2. Body: envelope.getEnvelope()

   important

   Always apply doNotGenerateTokensForOptedOut(). This applies a parameter similar to setting optout_check=1 in the call to the POST /token/generate endpoint (see Unencrypted JSON Body Parameters).

4. If the HTTP response status code is not 200, see Response Status Codes to determine next steps. Otherwise, convert the UID2 identity response content into a TokenGenerateResponse object:

   TokenGenerateResponse tokenGenerateResponse = publisherUid2Helper.createTokenGenerateResponse({response body}, envelope);

Client-Server Integration

If you're using client-server integration (see Client-Server Integration Guide for JavaScript), follow this step:

• Send this identity as a JSON string back to the client (to use in the identity field) using the following:

  tokenGenerateResponse.getIdentityJsonString()
  caution

  This method returns null if the user has opted out, so be sure to handle that case.

Server-Side Integration

If you're using server-side integration (see Publisher Integration Guide, Server-Side):

1. Store this identity as a JSON string in the user's session, using: tokenGenerateResponse.getIdentityJsonString().

   This method returns null if the user has opted out, so be sure to handle that case.

2. To retrieve the user's UID2 token, use:

   IdentityTokens identity = tokenGenerateResponse.getIdentity();
   if (identity != null) { String advertisingToken = identity.getAdvertisingToken(); }

3. When the user accesses another page, or on a timer, determine whether a refresh is needed:

   1. Retrieve the identity JSON string from the user's session, and then call the following function that generates an IdentityTokens object:

      IdentityTokens identity = IdentityTokens.fromJsonString(identityJsonString);

   2. Determine whether the identity can be refreshed (that is, the refresh token hasn't expired):

      if (identity == null || !identity.isRefreshable()) { we must no longer use this identity (for example, remove this identity from the user's session) }

   3. Determine whether a refresh is needed:

      if (identity.isDueForRefresh()) {..}

4. If a refresh is needed, call the POST token/refresh endpoint, with the following:

   1. Headers: Depending on your HTTP library, this might look something like the following:

      .putHeader("Authorization", "Bearer " + UID2_API_KEY)
.putHeader("X-UID2-Client-Version", PublisherUid2Helper.getVersionHeader()).

   2. Body: identity.getRefreshToken()

5. If the refresh HTTP response status code is 200:

   TokenRefreshResponse tokenRefreshResponse = PublisherUid2Helper.createTokenRefreshResponse({response body}, identity);

6. Store tokenRefreshResponse.getIdentityJsonString() in the user's session.

   If the user has opted out, this method returns null, indicating that the user's identity should be removed from the session. To confirm optout, you can use the tokenRefreshResponse.isOptout() function.

Usage for Advertisers/Data Providers

1. Create an instance of IdentityMapClient as an instance variable.

   final private IdentityMapClient identityMapClient = new IdentityMapClient(UID2_BASE_URL, UID2_API_KEY, UID2_SECRET_KEY);

2. Call a function that takes email addresses or phone numbers as input and generates an IdentityMapResponse object. The following example uses email addresses:

   IdentityMapResponse identityMapResponse = identityMapClient.generateIdentityMap(IdentityMapInput.fromEmails(Arrays.asList("email1@example.com", "email2@example.com")));

Note: The SDK hashes input values before sending them. This ensures that raw email addresses and phone numbers do not leave your server.

3. Retrieve the mapped and unmapped results as follows:

   Map<String, IdentityMapResponse.MappedIdentity> mappedIdentities = identityMapResponse.getMappedIdentities();
   Map<String, IdentityMapResponse.UnmappedIdentity> unmappedIdentities = identityMapResponse.getUnmappedIdentities();`

4. Iterate through the mapped and unmapped results, or do a lookup. The following example does a lookup:

   IdentityMapResponse.MappedIdentity mappedIdentity = mappedIdentities.get("email1@example.com");
   if (mappedIdentity != null) {
        String rawUid = mappedIdentity.getRawUid();
   } else {
        IdentityMapResponse.UnmappedIdentity unmappedIdentity = unmappedIdentities.get("email1@example.com");
        String reason = unmappedIdentity.getReason();
   }

Usage for DSPs

The following instructions provide an example of how a DSP can decode bidstream tokens using the UID2 SDK for Java.

1. Create a BidstreamClient:

Bidstream client = new BidstreamClient(UID2_BASE_URL, UID2_API_KEY, UID2_SECRET_KEY);

2. Refresh once at startup, and then periodically (recommended refresh interval is hourly):

client.refresh();

3. Decrypt a token into a raw UID2. Pass the token, and then do one of the following:

• If the bid request originated from a publisher's website, pass the domain name. The domain name must be all lower case, without spaces and without subdomain. For example, for Subdomain.DOMAIN.com, pass domain.com instead.
• If the bid request originated from a mobile app, pass the app name.
• Otherwise, pass null.

DecryptionResponse decrypted = client.decryptTokenIntoRawUid(uidToken, domainOrAppName); 
//If decryption succeeded, use the raw UID2.
if (decrypted.isSuccess()) 
{
    //Use decrypted.getUid()
}
else 
{
    // Check decrypted.getStatus() for the failure reason.
}

For a full example, see the ExampleBidStreamClient method in test/IntegrationExamples.java.

Usage for UID2 Sharers

A UID2 sharing participant is a company that takes part in sharing, either as a sender or a receiver, to share UID2s with another participant.

Advertisers and data providers can use this SDK to share UID2s with other authorized UID2 sharing participants (tokenized sharing). They can encrypt raw UID2s into UID2 tokens and then send them to another participant for sharing in pixels (see Tokenized Sharing in Pixels). If you are not sending data in pixels, you can take part in UID2 sharing as long as you follow the requirements laid out in Security Requirements for UID2 Sharing.

important

The UID2 token generated during this process is for sharing only—you cannot use it in the bidstream. There is a different workflow for generating tokens for the bidstream: see Tokenized Sharing in the Bidstream.

The following instructions provide an example of how you can implement sharing using the UID2 SDK for Java, either as a sender or a receiver.

1. Create a SharingClient:

SharingClient client = new SharingClient(UID2_BASE_URL, UID2_API_KEY, UID2_SECRET_KEY);

2. Refresh once at startup, and then periodically. Recommended refresh interval is hourly: for details, see Decryption Key Refresh Cadence for Sharing.

client.refresh();

3. If you are a sender, call encryptRawUidIntoToken:

EncryptionDataResponse encrypted = client.encryptRawUidIntoToken(raw_uid);
// If encryption succeeded, send the UID2 token to the receiver.
if (encrypted.isSuccess())
{
        // Send encrypted.getEncryptedData() to receiver
}
else
{
        // Check encrypted.getStatus() for the failure reason.
}

If you are a receiver, call decryptTokenIntoRawUid:

DecryptionResponse decrypted = client.decryptTokenIntoRawUid(uid_token);
// If decryption succeeded, use the raw UID2.
if (decrypted.isSuccess())
{
    //  Use decrypted.getUid()
}
else
{
    // Check decrypted.getStatus() for the failure reason.
}

For a full example, see the ExampleSharingClient method in test/IntegrationExamples.java.

FAQs

For a list of frequently asked questions for DSPs, see FAQs for DSPs.