Generate and use .vbprivk files for signing now.

build_image

Index: build_image
diff --git a/build_image b/build_image
index 983aa707fc4c56e828953fbd4f7c5336af8375c7..05d4a517322efda10929766bd062b48daf5b41c6 100755
--- a/build_image
+++ b/build_image
@@ -558,7 +558,7 @@ EOF
   if [[ "${ARCH}" = "x86" ]]; then
     # Verify the final image.
     load_kernel_test "${OUTPUT_DIR}/${image_name}" \
-      "${OUTPUT_DIR}/key_alg8.vbpubk"
+      "${OUTPUT_DIR}/kernel_subkey.vbpubk"
   fi
 }
 
@@ -602,8 +602,11 @@ fi
 
 # Clean up temporary files.
 rm -f "${ROOT_FS_IMG}" "${STATEFUL_FS_IMG}" "${OUTPUT_DIR}/vmlinuz.image" \
-  "${ESP_FS_IMG}" "${OUTPUT_DIR}/data4_sign8.keyblock" \
-  "${OUTPUT_DIR}/key_alg4.vbpubk" "${OUTPUT_DIR}/key_alg8.vbpubk" \
+  "${ESP_FS_IMG}" "${OUTPUT_DIR}/kernel.keyblock" \
+  "${OUTPUT_DIR}/kernel_subkey.vbpubk" \
+  "${OUTPUT_DIR}/kernel_subkey.vbprivk" \
+  "${OUTPUT_DIR}/kernel_data_key.vbpubk" \
+  "${OUTPUT_DIR}/kernel_data_key.vbprivk" \
   "${OEM_FS_IMG}"
 rmdir "${ROOT_FS_DIR}" "${STATEFUL_FS_DIR}" "${OEM_FS_DIR}" "${ESP_FS_DIR}"