diff --git a/delta_performer.cc b/delta_performer.cc
index 6466795..96bc7f4 100644
--- a/delta_performer.cc
+++ b/delta_performer.cc
@@ -554,10 +554,23 @@
   TEST_AND_RETURN_FALSE(signatures_message_data_.empty());
   TEST_AND_RETURN_FALSE(buffer_offset_ == manifest_.signatures_offset());
   TEST_AND_RETURN_FALSE(buffer_.size() >= manifest_.signatures_size());
-  signatures_message_data_.insert(
-      signatures_message_data_.begin(),
+  signatures_message_data_.assign(
       buffer_.begin(),
       buffer_.begin() + manifest_.signatures_size());
+
+  // Save the signature blob because if the update is interrupted after the
+  // download phase we don't go through this path anymore. Some alternatives to
+  // consider:
+  //
+  // 1. On resume, re-download the signature blob from the server and re-verify
+  // it.
+  //
+  // 2. Verify the signature as soon as it's received and don't checkpoint the
+  // blob and the signed sha-256 context.
+  LOG_IF(WARNING, !prefs_->SetString(kPrefsUpdateStateSignatureBlob,
+                                     string(&signatures_message_data_[0],
+                                            signatures_message_data_.size())))
+      << "Unable to store the signature blob.";
   // The hash of all data consumed so far should be verified against the signed
   // hash.
   signed_hash_context_ = hash_calculator_.GetContext();
@@ -726,6 +739,7 @@
     prefs->SetInt64(kPrefsUpdateStateNextDataOffset, -1);
     prefs->SetString(kPrefsUpdateStateSHA256Context, "");
     prefs->SetString(kPrefsUpdateStateSignedSHA256Context, "");
+    prefs->SetString(kPrefsUpdateStateSignatureBlob, "");
     prefs->SetInt64(kPrefsManifestMetadataSize, -1);
     prefs->SetInt64(kPrefsResumedUpdateFailures, 0);
   }
@@ -770,10 +784,15 @@
                         next_data_offset >= 0);
   buffer_offset_ = next_data_offset;
 
-  // The signed hash context may be empty if the interrupted update didn't reach
-  // the signature blob.
+  // The signed hash context and the signature blob may be empty if the
+  // interrupted update didn't reach the signature.
   prefs_->GetString(kPrefsUpdateStateSignedSHA256Context,
                     &signed_hash_context_);
+  string signature_blob;
+  if (prefs_->GetString(kPrefsUpdateStateSignatureBlob, &signature_blob)) {
+    signatures_message_data_.assign(signature_blob.begin(),
+                                    signature_blob.end());
+  }
 
   string hash_context;
   TEST_AND_RETURN_FALSE(prefs_->GetString(kPrefsUpdateStateSHA256Context,
diff --git a/delta_performer_unittest.cc b/delta_performer_unittest.cc
index df73e56..3bdb2d8 100644
--- a/delta_performer_unittest.cc
+++ b/delta_performer_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -412,6 +412,8 @@
   if (signature_test != kSignatureNone) {
     EXPECT_CALL(prefs, SetString(kPrefsUpdateStateSignedSHA256Context, _))
         .WillOnce(Return(true));
+    EXPECT_CALL(prefs, SetString(kPrefsUpdateStateSignatureBlob, _))
+        .WillOnce(Return(true));
   }
 
   // Update the A image in place.
diff --git a/prefs.cc b/prefs.cc
index 1bde4cd..94d0baa 100644
--- a/prefs.cc
+++ b/prefs.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -25,6 +25,7 @@
 const char kPrefsUpdateStateNextDataOffset[] = "update-state-next-data-offset";
 const char kPrefsUpdateStateNextOperation[] = "update-state-next-operation";
 const char kPrefsUpdateStateSHA256Context[] = "update-state-sha-256-context";
+const char kPrefsUpdateStateSignatureBlob[] = "update-state-signature-blob";
 const char kPrefsUpdateStateSignedSHA256Context[] =
     "update-state-signed-sha-256-context";
 
diff --git a/prefs_interface.h b/prefs_interface.h
index 8d07dde..ddebb3b 100644
--- a/prefs_interface.h
+++ b/prefs_interface.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -19,6 +19,7 @@
 extern const char kPrefsUpdateStateNextDataOffset[];
 extern const char kPrefsUpdateStateNextOperation[];
 extern const char kPrefsUpdateStateSHA256Context[];
+extern const char kPrefsUpdateStateSignatureBlob[];
 extern const char kPrefsUpdateStateSignedSHA256Context[];
 
 // The prefs interface allows access to a persistent preferences