Accept both base64 and base64url tokens in the bidstream

This behaviour matches that of the .NET SDK.

Author: mcollins-ttd

src/main/java/com/uid2/client/Uid2Encryption.java

@@ -43,13 +43,19 @@ static DecryptionResponse decrypt(String token, KeyContainer keys, Instant now,
         }
         else if (unsignedByte  == AdvertisingTokenVersion.V4.value())
         {
-            //same as V3 but use Base64URL encoding
-            return decryptV3(Uid2Base64UrlCoder.decode(token), keys, now, identityScope, domainName, clientType, 4);
+            // Accept either base64 or base64url encoding.
+            return decryptV3(Base64.getDecoder().decode(base64UrlToBase64(token)), keys, now, identityScope, domainName, clientType, 4);
         }
 
         return DecryptionResponse.makeError(DecryptionStatus.VERSION_NOT_SUPPORTED);
     }
 
+    static String base64UrlToBase64(String value) {
+        // Base64 decoder doesn't require padding.
+        return value.replace('-', '+')
+                .replace('_', '/');
+    }
+
     static DecryptionResponse decryptV2(byte[] encryptedId, KeyContainer keys, Instant now, String domainName, ClientType clientType) throws Exception {
         try {
             ByteBuffer rootReader = ByteBuffer.wrap(encryptedId);

src/test/java/com/uid2/client/BidstreamClientTests.java

@@ -4,15 +4,13 @@
 import com.google.gson.JsonObject;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.Arguments;
-import org.junit.jupiter.params.provider.CsvSource;
-import org.junit.jupiter.params.provider.MethodSource;
-import org.junit.jupiter.params.provider.ValueSource;
+import org.junit.jupiter.params.provider.*;
 
 import java.time.Duration;
 import java.time.Instant;
 import java.time.temporal.ChronoUnit;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.stream.Stream;
 
 import static com.uid2.client.EncryptionTestsV4.validateAdvertisingToken;
@@ -288,6 +286,26 @@ public void tokenExpiryAndCustomNow() throws Exception {
         assertEquals(EXAMPLE_UID, res.getUid());
     }
 
+    @ParameterizedTest
+    @EnumSource(IdentityScope.class)
+    void decryptV4TokenEncodedAsBase64(IdentityScope identityScope) throws Exception {
+        refresh(keyBidstreamResponse(identityScope, MASTER_KEY, SITE_KEY));
+
+        String advertisingToken;
+        do {
+            advertisingToken = AdvertisingTokenBuilder.builder()
+                    .withVersion(TokenVersionForTesting.V4)
+                    .withScope(identityScope)
+                    .build();
+
+            byte[] tokenAsBytes = Uid2Base64UrlCoder.decode(advertisingToken);
+            advertisingToken = Base64.getEncoder().encodeToString(tokenAsBytes);
+        }
+        while (!advertisingToken.contains("=") || !advertisingToken.contains("/") || !advertisingToken.contains("+"));
+
+        decryptAndAssertSuccess(advertisingToken, TokenVersionForTesting.V4);
+    }
+
     private void refresh(String json) {
         RefreshResponse refreshResponse = bidstreamClient.refreshJson(json);
         assertTrue(refreshResponse.isSuccess());