Write identity key into 'account' object.

This is the beginning of a migration to storing one identity
key per account, instead of the braindead duplication we're
doing now.  Part one of a two-part deployment in the schema
migration process.

src/main/java/org/whispersystems/textsecuregcm/controllers/KeysController.java

@@ -70,7 +70,14 @@ public class KeysController {
   @PUT
   @Consumes(MediaType.APPLICATION_JSON)
   public void setKeys(@Auth Account account, @Valid PreKeyList preKeys)  {
-    Device device = account.getAuthenticatedDevice().get();
+    Device device      = account.getAuthenticatedDevice().get();
+    String identityKey = preKeys.getLastResortKey().getIdentityKey();
+
+    if (!identityKey.equals(account.getIdentityKey())) {
+      account.setIdentityKey(identityKey);
+      accounts.update(account);
+    }
+
     keys.store(account.getNumber(), device.getId(), preKeys.getKeys(), preKeys.getLastResortKey());
   }
 

src/main/java/org/whispersystems/textsecuregcm/entities/PreKeyList.java

@@ -17,6 +17,7 @@
 package org.whispersystems.textsecuregcm.entities;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.annotations.VisibleForTesting;
 import org.hibernate.validator.constraints.NotEmpty;
 
 import javax.validation.Valid;
@@ -27,6 +28,7 @@ public class PreKeyList {
 
   @JsonProperty
   @NotNull
+  @Valid
   private PreKey lastResortKey;
 
   @JsonProperty
@@ -38,7 +40,17 @@ public class PreKeyList {
     return keys;
   }
 
+  @VisibleForTesting
+  public void setKeys(List<PreKey> keys) {
+    this.keys = keys;
+  }
+
   public PreKey getLastResortKey() {
     return lastResortKey;
   }
+
+  @VisibleForTesting
+  public void setLastResortKey(PreKey lastResortKey) {
+    this.lastResortKey = lastResortKey;
+  }
 }

src/main/java/org/whispersystems/textsecuregcm/storage/Account.java

@@ -28,7 +28,7 @@ import java.util.List;
 
 public class Account implements Serializable {
 
-  public static final int MEMCACHE_VERION = 2;
+  public static final int MEMCACHE_VERION = 3;
 
   @JsonIgnore
   private long id;
@@ -42,16 +42,14 @@ public class Account implements Serializable {
   @JsonProperty
   private List<Device> devices = new LinkedList<>();
 
+  @JsonProperty
+  private String identityKey;
+
   @JsonIgnore
   private Optional<Device> authenticatedDevice;
 
   public Account() {}
 
-  public Account(String number, boolean supportsSms) {
-    this.number      = number;
-    this.supportsSms = supportsSms;
-  }
-
   @VisibleForTesting
   public Account(String number, boolean supportsSms, List<Device> devices) {
     this.number      = number;
@@ -142,4 +140,12 @@ public class Account implements Serializable {
   public Optional<String> getRelay() {
     return Optional.absent();
   }
+
+  public void setIdentityKey(String identityKey) {
+    this.identityKey = identityKey;
+  }
+
+  public String getIdentityKey() {
+    return identityKey;
+  }
 }