session-android/library/src/org/whispersystems/textsecure/push/SignedPreKeyEntity.java

package org.whispersystems.textsecure.push;

import com.google.thoughtcrimegson.GsonBuilder;
import com.google.thoughtcrimegson.JsonDeserializationContext;
import com.google.thoughtcrimegson.JsonDeserializer;
import com.google.thoughtcrimegson.JsonElement;
import com.google.thoughtcrimegson.JsonParseException;
import com.google.thoughtcrimegson.JsonPrimitive;
import com.google.thoughtcrimegson.JsonSerializationContext;
import com.google.thoughtcrimegson.JsonSerializer;

import org.whispersystems.libaxolotl.ecc.ECPublicKey;
import org.whispersystems.textsecure.util.Base64;

import java.io.IOException;
import java.lang.reflect.Type;

public class SignedPreKeyEntity extends PreKeyEntity {

  private byte[] signature;

  public SignedPreKeyEntity() {}

  public SignedPreKeyEntity(int keyId, ECPublicKey publicKey, byte[] signature) {
    super(keyId, publicKey);
    this.signature = signature;
  }

  public byte[] getSignature() {
    return signature;
  }

  public static GsonBuilder forBuilder(GsonBuilder builder) {
    return PreKeyEntity.forBuilder(builder)
                       .registerTypeAdapter(byte[].class, new ByteArrayJsonAdapter());

  }

  private static class ByteArrayJsonAdapter
      implements JsonSerializer<byte[]>, JsonDeserializer<byte[]>
  {
    @Override
    public JsonElement serialize(byte[] signature, Type type,
                                 JsonSerializationContext jsonSerializationContext)
    {
      return new JsonPrimitive(Base64.encodeBytesWithoutPadding(signature));
    }

    @Override
    public byte[] deserialize(JsonElement jsonElement, Type type,
                              JsonDeserializationContext jsonDeserializationContext)
        throws JsonParseException
    {
      try {
        return Base64.decodeWithoutPadding(jsonElement.getAsJsonPrimitive().getAsString());
      } catch (IOException e) {
        throw new JsonParseException(e);
      }
    }
  }
}