diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..6434aaf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+./key
+./key.pub
diff --git a/functions b/functions
index 1f0f68e..809fc40 100644
--- a/functions
+++ b/functions
@@ -6,5 +6,22 @@ get_stack () {
 	fi
 }
 
+# Generar una llave privada ECDSA si no existe
+generate_private_key () {
+  test -f "$private_key" && return 1
 
+  ssh-keygen -t ecdsa -f "$private_key" -N "" -C "$@"
+}
 
+# Firmar el archivo usando la llave privada.
+#
+# Uso: sign_file archivo.json
+# Devuelve: La firma
+sign_file () {
+  local _file="$1"
+
+  test ! -f "$_file" && return 1
+  test -f "$_file.sig" || ssh-keygen -Y sign -f "$private_key" -n file "$_file" 2>&1 >/dev/null
+
+  cat "${_file}.sig" | grep -v SIGNATURE | tr -d "\n"
+}
diff --git a/nodemecu.conf.sample b/nodemecu.conf.sample
index bfb5883..84b73a1 100644
--- a/nodemecu.conf.sample
+++ b/nodemecu.conf.sample
@@ -14,3 +14,4 @@ stack=$install_dir/stack
 historical=$install_dir/historical
 log=$install_dir/errors.log
 corrupt=$install_dir/corrupt
+private_key=$install_dir/key