upstream: Add protection for private keys at rest in RAM against

speculation and memory sidechannel attacks like Spectre, Meltdown, Rowhammer
and Rambleed. This change encrypts private keys when they are not in use with
a symmetic key that is derived from a relatively large "prekey" consisting of
random data (currently 16KB).

Attackers must recover the entire prekey with high accuracy before
they can attempt to decrypt the shielded private key, but the current
generation of attacks have bit error rates that, when applied
cumulatively to the entire prekey, make this unlikely.

Implementation-wise, keys are encrypted "shielded" when loaded and then
automatically and transparently unshielded when used for signatures or
when being saved/serialised.

Hopefully we can remove this in a few years time when computer
architecture has become less unsafe.

been in snaps for a bit already; thanks deraadt@

ok dtucker@ deraadt@

OpenBSD-Commit-ID: 19767213c312e46f94b303a512ef8e9218a39bd4

1 files changed, 2 insertions, 2 deletions

diff --git a/krl.h b/krl.h
index 815a1df4..ce534a11 100644
--- a/krl.h
+++ b/krl.h
@@ -14,7 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $OpenBSD: krl.h,v 1.6 2018/09/12 01:21:34 djm Exp $ */
+/* $OpenBSD: krl.h,v 1.7 2019/06/21 04:21:04 djm Exp $ */
 
 #ifndef _KRL_H
 #define _KRL_H
@@ -56,7 +56,7 @@ int ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const u_char *p, size_t len);
 int ssh_krl_revoke_key_sha256(struct ssh_krl *krl, const u_char *p, size_t len);
 int ssh_krl_revoke_key(struct ssh_krl *krl, const struct sshkey *key);
 int ssh_krl_to_blob(struct ssh_krl *krl, struct sshbuf *buf,
-    const struct sshkey **sign_keys, u_int nsign_keys);
+    struct sshkey **sign_keys, u_int nsign_keys);
 int ssh_krl_from_blob(struct sshbuf *buf, struct ssh_krl **krlp,
     const struct sshkey **sign_ca_keys, size_t nsign_ca_keys);
 int ssh_krl_check_key(struct ssh_krl *krl, const struct sshkey *key);