diff --git a/README.md b/README.md
index 7aa67d1..c6c8ea1 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,5 @@
 
 Maneja los certificados de sello y FIEL fácilmente
 
+
+## Software libre, NO gratis.
diff --git a/requirements.txt b/requirements.txt
index 204bb1d..c909f0e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,2 @@
 xmlsec
-cryptography
+cryptography==3.4.8