upstream: support PKCS8 as an optional format for storage of

private keys, enabled via "ssh-keygen -m PKCS8" on operations that save
private keys to disk.

The OpenSSH native key format remains the default, but PKCS8 is a
superior format to PEM if interoperability with non-OpenSSH software
is required, as it may use a less terrible KDF (IIRC PEM uses a single
round of MD5 as a KDF).

adapted from patch by Jakub Jelen via bz3013; ok markus

OpenBSD-Commit-ID: 027824e3bc0b1c243dc5188504526d73a55accb1

1 files changed, 14 insertions, 11 deletions

diff --git a/ssh-keygen.c b/ssh-keygen.c
index b019a02ff..5dcad1f61 100644
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keygen.c,v 1.335 2019/07/05 07:32:01 djm Exp $ */
+/* $OpenBSD: ssh-keygen.c,v 1.336 2019/07/15 13:16:29 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -147,11 +147,11 @@ static char *key_type_name = NULL;
 /* Load key from this PKCS#11 provider */
 static char *pkcs11provider = NULL;
 
-/* Use new OpenSSH private key format when writing SSH2 keys instead of PEM */
-static int use_new_format = 1;
+/* Format for writing private keys */
+static int private_key_format = SSHKEY_PRIVATE_OPENSSH;
 
 /* Cipher for new-format private keys */
-static char *new_format_cipher = NULL;
+static char *openssh_format_cipher = NULL;
 
 /*
  * Number of KDF rounds to derive new format keys /
@@ -1048,7 +1048,8 @@ do_gen_all_hostkeys(struct passwd *pw)
                 snprintf(comment, sizeof comment, "%s@%s", pw->pw_name,
                     hostname);
                 if ((r = sshkey_save_private(private, prv_tmp, "",
-                    comment, use_new_format, new_format_cipher, rounds)) != 0) {
+                    comment, private_key_format, openssh_format_cipher,
+                    rounds)) != 0) {
                         error("Saving key \"%s\" failed: %s",
                             prv_tmp, ssh_err(r));
                         goto failnext;
@@ -1391,7 +1392,7 @@ do_change_passphrase(struct passwd *pw)
 
         /* Save the file using the new passphrase. */
         if ((r = sshkey_save_private(private, identity_file, passphrase1,
-            comment, use_new_format, new_format_cipher, rounds)) != 0) {
+            comment, private_key_format, openssh_format_cipher, rounds)) != 0) {
                 error("Saving key \"%s\" failed: %s.",
                     identity_file, ssh_err(r));
                 explicit_bzero(passphrase1, strlen(passphrase1));
@@ -1480,7 +1481,7 @@ do_change_comment(struct passwd *pw, const char *identity_comment)
         }
 
         if (private->type != KEY_ED25519 && private->type != KEY_XMSS &&
-            !use_new_format) {
+            private_key_format != SSHKEY_PRIVATE_OPENSSH) {
                 error("Comments are only supported for keys stored in "
                     "the new format (-o).");
                 explicit_bzero(passphrase, strlen(passphrase));
@@ -1514,7 +1515,8 @@ do_change_comment(struct passwd *pw, const char *identity_comment)
 
         /* Save the file using the new passphrase. */
         if ((r = sshkey_save_private(private, identity_file, passphrase,
-            new_comment, use_new_format, new_format_cipher, rounds)) != 0) {
+            new_comment, private_key_format, openssh_format_cipher,
+            rounds)) != 0) {
                 error("Saving key \"%s\" failed: %s",
                     identity_file, ssh_err(r));
                 explicit_bzero(passphrase, strlen(passphrase));
@@ -2525,11 +2527,12 @@ main(int argc, char **argv)
                         }
                         if (strcasecmp(optarg, "PKCS8") == 0) {
                                 convert_format = FMT_PKCS8;
+                                private_key_format = SSHKEY_PRIVATE_PKCS8;
                                 break;
                         }
                         if (strcasecmp(optarg, "PEM") == 0) {
                                 convert_format = FMT_PEM;
-                                use_new_format = 0;
+                                private_key_format = SSHKEY_PRIVATE_PEM;
                                 break;
                         }
                         fatal("Unsupported conversion format \"%s\"", optarg);
@@ -2567,7 +2570,7 @@ main(int argc, char **argv)
                         add_cert_option(optarg);
                         break;
                 case 'Z':
-                        new_format_cipher = optarg;
+                        openssh_format_cipher = optarg;
                         break;
                 case 'C':
                         identity_comment = optarg;
@@ -2912,7 +2915,7 @@ passphrase_again:
 
         /* Save the key with the given passphrase and comment. */
         if ((r = sshkey_save_private(private, identity_file, passphrase1,
-            comment, use_new_format, new_format_cipher, rounds)) != 0) {
+            comment, private_key_format, openssh_format_cipher, rounds)) != 0) {
                 error("Saving key \"%s\" failed: %s",
                     identity_file, ssh_err(r));
                 explicit_bzero(passphrase1, strlen(passphrase1));