updated for version 7.4.509

Problem:    Users are not aware their encryption is weak.
Solution:   Give a warning when prompting for the key.

src/crypt.c

@@ -503,6 +503,26 @@ crypt_free_key(key)
     }
 }
 
+/*
+ * Check the crypt method and give a warning if it's outdated.
+ */
+    void
+crypt_check_method(method)
+    int method;
+{
+    if (method < CRYPT_M_BF2)
+    {
+	msg_scroll = TRUE;
+	MSG(_("Warning: Using a weak encryption method; see :help 'cm'"));
+    }
+}
+
+    void
+crypt_check_current_method()
+{
+    crypt_check_method(crypt_get_method_nr(curbuf));
+}
+
 /*
  * Ask the user for a crypt key.
  * When "store" is TRUE, the new key is stored in the 'key' option, and the

src/ex_docmd.c

@@ -11524,6 +11524,7 @@ ex_match(eap)
 ex_X(eap)
     exarg_T	*eap UNUSED;
 {
+    crypt_check_current_method();
     (void)crypt_get_key(TRUE, TRUE);
 }
 #endif

src/fileio.c

@@ -2958,6 +2958,7 @@ check_for_cryptkey(cryptkey, ptr, sizep, filesizep, newfile, fname, did_ask)
 		 * Happens when retrying to detect encoding. */
 		smsg((char_u *)_(need_key_msg), fname);
 		msg_scroll = TRUE;
+		crypt_check_method(method);
 		cryptkey = crypt_get_key(newfile, FALSE);
 		*did_ask = TRUE;
 

src/main.c

@@ -854,6 +854,7 @@ vim_main2(int argc UNUSED, char **argv UNUSED)
 #ifdef FEAT_CRYPT
     if (params.ask_for_key)
     {
+	crypt_check_current_method();
 	(void)crypt_get_key(TRUE, TRUE);
 	TIME_MSG("getting crypt key");
     }

src/proto/crypt.pro

@@ -19,6 +19,8 @@ void crypt_decode __ARGS((cryptstate_T *state, char_u *from, size_t len, char_u
 void crypt_encode_inplace __ARGS((cryptstate_T *state, char_u *buf, size_t len));
 void crypt_decode_inplace __ARGS((cryptstate_T *state, char_u *buf, size_t len));
 void crypt_free_key __ARGS((char_u *key));
+void crypt_check_method __ARGS((int method));
+void crypt_check_current_method __ARGS((void));
 char_u *crypt_get_key __ARGS((int store, int twice));
 void crypt_append_msg __ARGS((buf_T *buf));
 /* vim: set ft=c : */

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    509,
 /**/
     508,
 /**/