diff --git a/modules/core/public/lib/validations/gpg.liquid b/modules/core/public/lib/validations/gpg.liquid
new file mode 100644
index 0000000..e4a809b
--- /dev/null
+++ b/modules/core/public/lib/validations/gpg.liquid
@@ -0,0 +1,8 @@
+{% liquid
+  assign valid_gpg = object[field_name]['key'] | is_gpg_valid
+  unless valid_gpg
+    assign message = 'modules/core/validation.invalid_gpg' | t
+    function c = 'modules/core/helpers/register_error', contract: c, field_name: field_name, message: message, key: key
+  endunless
+  return c
+%}
diff --git a/modules/core/public/translations/en/validation.yml b/modules/core/public/translations/en/validation.yml
index 06a1a48..87dde99 100644
--- a/modules/core/public/translations/en/validation.yml
+++ b/modules/core/public/translations/en/validation.yml
@@ -48,3 +48,4 @@ en:
       number: must include at least one number
     invalid: invalid
     not_exist: not exist
+    invalid_gpg: must be a valid GPG key