From 48d92bcc8870f5750fb66351f3623f9d874d08fa Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Wed, 25 Jun 2014 20:25:28 +0200
Subject: [PATCH] gpg: Limit keysize for unattended key generation to useful
 values.

* g10/keygen.c (gen_elg): Enforce keysize 1024 to 4096.
(gen_rsa): Enforce keysize 1024 to 4096.
(gen_dsa): Enforce keysize 768 to 3072.
--

It was possible to create 16k RSA keys in batch mode. In addition to the
silliness of such keys, they have the major drawback that under GnuPG
and Libgcrypt, with their limited amount of specially secured memory
areas, the use of such keys may lead to an "out of secure memory"
condition.
---
 g10/keygen.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/g10/keygen.c b/g10/keygen.c
index a786beb08..6d3dfa69b 100644
--- a/g10/keygen.c
+++ b/g10/keygen.c
@@ -1170,11 +1170,16 @@ gen_elg (int algo, unsigned int nbits,
 
   assert( is_ELGAMAL(algo) );
 
-  if (nbits < 512)
+  if (nbits < 1024)
     {
       nbits = 2048;
       log_info (_("keysize invalid; using %u bits\n"), nbits );
     }
+  else if (nbits > 4096)
+    {
+      nbits = 4096;
+      log_info (_("keysize invalid; using %u bits\n"), nbits );
+    }
 
   if ((nbits % 32))
     {
@@ -1281,7 +1286,7 @@ gen_dsa (unsigned int nbits, KBNODE pub_root, KBNODE sec_root, DEK *dek,
   gcry_sexp_t misc_key_info;
   unsigned int qbits;
 
-  if ( nbits < 512)
+  if (nbits < 768)
     {
       nbits = 2048;
       log_info(_("keysize invalid; using %u bits\n"), nbits );
@@ -1437,6 +1442,11 @@ gen_rsa (int algo, unsigned nbits, KBNODE pub_root, KBNODE sec_root, DEK *dek,
       nbits = 2048;
       log_info (_("keysize invalid; using %u bits\n"), nbits );
     }
+  else if (nbits > 4096)
+    {
+      nbits = 4096;
+      log_info (_("keysize invalid; using %u bits\n"), nbits );
+    }
 
   if ((nbits % 32))
     {