gpg: New command --export-ssh-key

* g10/export.c: Include membuf.h and host2net.h.
(key_to_sshblob): New.
(export_ssh_key): New.
* g10/gpg.c (aExportSshKey): New.
(opts): Add command.
(main): Implement that command.
--

GnuPG-bug-id: 2212

I have done only a few tests rights now and the ECDSA curves do not
yet work.  However ssh-keygen -l accept RSA and ed25519 keys exported
using this command.

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2016-01-08 17:22:32 +01:00
parent 34bca9cd4b
commit 4970868d8d
No known key found for this signature in database
GPG Key ID: E3FDFF218E45B72B
3 changed files with 312 additions and 2 deletions

View File

@ -1,7 +1,7 @@
/* export.c - Export keys in the OpenPGP defined format.
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
* 2005, 2010 Free Software Foundation, Inc.
* Copyright (C) 1998-2015 Werner Koch
* Copyright (C) 1998-2016 Werner Koch
*
* This file is part of GnuPG.
*
@ -34,6 +34,8 @@
#include "util.h"
#include "main.h"
#include "i18n.h"
#include "membuf.h"
#include "host2net.h"
#include "trustdb.h"
#include "call-agent.h"
@ -1350,3 +1352,295 @@ do_export_stream (ctrl_t ctrl, iobuf_t out, strlist_t users, int secret,
log_info(_("WARNING: nothing exported\n"));
return err;
}
static gpg_error_t
key_to_sshblob (membuf_t *mb, const char *identifier, ...)
{
va_list arg_ptr;
gpg_error_t err = 0;
unsigned char nbuf[4];
unsigned char *buf;
size_t buflen;
gcry_mpi_t a;
ulongtobuf (nbuf, (ulong)strlen (identifier));
put_membuf (mb, nbuf, 4);
put_membuf_str (mb, identifier);
va_start (arg_ptr, identifier);
while ((a = va_arg (arg_ptr, gcry_mpi_t)))
{
err = gcry_mpi_aprint (GCRYMPI_FMT_SSH, &buf, &buflen, a);
if (err)
break;
if (!strcmp (identifier, "ssh-ed25519")
&& buflen > 5 && buf[4] == 0x40)
{
/* We need to strip our 0x40 prefix. */
put_membuf (mb, "\x00\x00\x00\x20", 4);
put_membuf (mb, buf+5, buflen-5);
}
else
put_membuf (mb, buf, buflen);
gcry_free (buf);
}
va_end (arg_ptr);
return err;
}
/* Export the key identified by USERID in the SSH public key format.
The function exports the latest subkey with Authentication
capability unless the '!' suffix is used to export a specific
key. */
gpg_error_t
export_ssh_key (ctrl_t ctrl, const char *userid)
{
gpg_error_t err;
kbnode_t keyblock = NULL;
KEYDB_SEARCH_DESC desc;
u32 latest_date;
u32 curtime = make_timestamp ();
kbnode_t latest_key, node;
PKT_public_key *pk;
const char *identifier;
membuf_t mb;
estream_t fp = NULL;
struct b64state b64_state;
const char *fname = "-";
init_membuf (&mb, 4096);
/* We need to know whether the key has been specified using the
exact syntax ('!' suffix). Thus we need to run a
classify_user_id on our own. */
err = classify_user_id (userid, &desc, 1);
/* Get the public key. */
if (!err)
{
getkey_ctx_t getkeyctx;
err = get_pubkey_byname (ctrl, &getkeyctx, NULL, userid, &keyblock,
NULL,
0 /* Only usable keys or given exact. */,
1 /* No AKL lookup. */);
if (!err)
{
err = getkey_next (getkeyctx, NULL, NULL);
if (!err)
err = gpg_error (GPG_ERR_AMBIGUOUS_NAME);
else if (gpg_err_code (err) == GPG_ERR_NO_PUBKEY)
err = 0;
}
getkey_end (getkeyctx);
}
if (err)
{
log_error (_("key \"%s\" not found: %s\n"), userid, gpg_strerror (err));
return err;
}
/* The finish_lookup code in getkey.c does not handle auth keys,
thus we have to duplicate the code here to find the latest
subkey. However, if the key has been found using an exact match
('!' notation) we use that key without any further checks and
even allow the use of the primary key. */
latest_date = 0;
latest_key = NULL;
for (node = keyblock; node; node = node->next)
{
if ((node->pkt->pkttype == PKT_PUBLIC_SUBKEY
|| node->pkt->pkttype == PKT_PUBLIC_KEY)
&& node->pkt->pkt.public_key->flags.exact)
{
latest_key = node;
break;
}
}
if (!latest_key)
{
for (node = keyblock; node; node = node->next)
{
if (node->pkt->pkttype != PKT_PUBLIC_SUBKEY)
continue;
pk = node->pkt->pkt.public_key;
if (DBG_LOOKUP)
log_debug ("\tchecking subkey %08lX\n",
(ulong) keyid_from_pk (pk, NULL));
if (!(pk->pubkey_usage & PUBKEY_USAGE_AUTH))
{
if (DBG_LOOKUP)
log_debug ("\tsubkey not usable for authentication\n");
continue;
}
if (!pk->flags.valid)
{
if (DBG_LOOKUP)
log_debug ("\tsubkey not valid\n");
continue;
}
if (pk->flags.revoked)
{
if (DBG_LOOKUP)
log_debug ("\tsubkey has been revoked\n");
continue;
}
if (pk->has_expired)
{
if (DBG_LOOKUP)
log_debug ("\tsubkey has expired\n");
continue;
}
if (pk->timestamp > curtime && !opt.ignore_valid_from)
{
if (DBG_LOOKUP)
log_debug ("\tsubkey not yet valid\n");
continue;
}
if (DBG_LOOKUP)
log_debug ("\tsubkey might be fine\n");
/* In case a key has a timestamp of 0 set, we make sure that it
is used. A better change would be to compare ">=" but that
might also change the selected keys and is as such a more
intrusive change. */
if (pk->timestamp > latest_date || (!pk->timestamp && !latest_date))
{
latest_date = pk->timestamp;
latest_key = node;
}
}
}
if (!latest_key)
{
err = gpg_error (GPG_ERR_UNUSABLE_PUBKEY);
log_error (_("key \"%s\" not found: %s\n"), userid, gpg_strerror (err));
goto leave;
}
pk = latest_key->pkt->pkt.public_key;
if (DBG_LOOKUP)
log_debug ("\tusing key %08lX\n", (ulong) keyid_from_pk (pk, NULL));
switch (pk->pubkey_algo)
{
case PUBKEY_ALGO_DSA:
identifier = "ssh-dss";
err = key_to_sshblob (&mb, identifier,
pk->pkey[0], pk->pkey[1], pk->pkey[2], pk->pkey[3],
NULL);
break;
case PUBKEY_ALGO_RSA:
case PUBKEY_ALGO_RSA_S:
identifier = "ssh-rsa";
err = key_to_sshblob (&mb, identifier, pk->pkey[1], pk->pkey[0], NULL);
break;
case PUBKEY_ALGO_ECDSA:
{
char *curveoid;
const char *curve;
curveoid = openpgp_oid_to_str (pk->pkey[0]);
if (!curveoid)
err = gpg_error_from_syserror ();
else if (!(curve = openpgp_oid_to_curve (curveoid, 0)))
err = gpg_error (GPG_ERR_UNKNOWN_CURVE);
else
{
if (!strcmp (curve, "nistp256"))
identifier = "ecdsa-sha2-nistp256";
else if (!strcmp (curve, "nistp384"))
identifier = "ecdsa-sha2-nistp384";
else if (!strcmp (curve, "nistp521"))
identifier = "ecdsa-sha2-nistp521";
else
identifier = NULL;
if (!identifier)
err = gpg_error (GPG_ERR_UNKNOWN_CURVE);
else
err = key_to_sshblob (&mb, identifier, pk->pkey[1], NULL);
}
xfree (curveoid);
}
break;
case PUBKEY_ALGO_EDDSA:
if (!openpgp_oid_is_ed25519 (pk->pkey[0]))
err = gpg_error (GPG_ERR_UNKNOWN_CURVE);
else
{
identifier = "ssh-ed25519";
err = key_to_sshblob (&mb, identifier, pk->pkey[1], NULL);
}
break;
case PUBKEY_ALGO_ELGAMAL_E:
case PUBKEY_ALGO_ELGAMAL:
err = gpg_error (GPG_ERR_UNUSABLE_PUBKEY);
break;
default:
err = GPG_ERR_PUBKEY_ALGO;
break;
}
if (err)
goto leave;
if (opt.outfile && *opt.outfile && strcmp (opt.outfile, "-"))
fp = es_fopen ((fname = opt.outfile), "w");
else
fp = es_stdout;
if (!fp)
{
err = gpg_error_from_syserror ();
log_error (_("error creating '%s': %s\n"), fname, gpg_strerror (err));
goto leave;
}
es_fprintf (fp, "%s ", identifier);
err = b64enc_start_es (&b64_state, fp, "");
if (err)
goto leave;
{
void *blob;
size_t bloblen;
blob = get_membuf (&mb, &bloblen);
if (!blob)
err = gpg_error_from_syserror ();
else
err = b64enc_write (&b64_state, blob, bloblen);
xfree (blob);
if (err)
goto leave;
}
err = b64enc_finish (&b64_state);
if (err)
goto leave;
es_fprintf (fp, " openpgp:0x%08lX\n", (ulong)keyid_from_pk (pk, NULL));
if (es_ferror (fp))
err = gpg_error_from_syserror ();
else
{
if (es_fclose (fp))
err = gpg_error_from_syserror ();
fp = NULL;
}
if (err)
log_error (_("error writing '%s': %s\n"), fname, gpg_strerror (err));
leave:
es_fclose (fp);
xfree (get_membuf (&mb, NULL));
release_kbnode (keyblock);
return err;
}

View File

@ -1,6 +1,6 @@
/* gpg.c - The GnuPG utility (main for gpg)
* Copyright (C) 1998-2011 Free Software Foundation, Inc.
* Copyright (C) 1997-2014 Werner Koch
* Copyright (C) 1997-2016 Werner Koch
* Copyright (C) 2015 g10 Code GmbH
*
* This file is part of GnuPG.
@ -141,6 +141,7 @@ enum cmd_and_opt_values
aExport,
aExportSecret,
aExportSecretSub,
aExportSshKey,
aCheckKeys,
aGenRevoke,
aDesigRevoke,
@ -453,6 +454,7 @@ static ARGPARSE_OPTS opts[] = {
ARGPARSE_c (aFetchKeys, "fetch-keys" , "@" ),
ARGPARSE_c (aExportSecret, "export-secret-keys" , "@" ),
ARGPARSE_c (aExportSecretSub, "export-secret-subkeys" , "@" ),
ARGPARSE_c (aExportSshKey, "export-ssh-key", "@" ),
ARGPARSE_c (aImport, "import", N_("import/merge keys")),
ARGPARSE_c (aFastImport, "fast-import", "@"),
#ifdef ENABLE_CARD_SUPPORT
@ -2400,6 +2402,7 @@ main (int argc, char **argv)
case aListSigs:
case aExportSecret:
case aExportSecretSub:
case aExportSshKey:
case aSym:
case aClearsign:
case aGenRevoke:
@ -4184,6 +4187,17 @@ main (int argc, char **argv)
free_strlist(sl);
break;
case aExportSshKey:
if (argc != 1)
wrong_args ("--export-ssh-key <user-id>");
rc = export_ssh_key (ctrl, argv[0]);
if (rc)
{
write_status_failure ("export-ssh-key", rc);
log_error (_("export as ssh key failed: %s\n"), gpg_strerror (rc));
}
break;
case aSearchKeys:
sl = NULL;
for (; argc; argc--, argv++)

View File

@ -368,6 +368,8 @@ gpg_error_t receive_seckey_from_agent (ctrl_t ctrl, gcry_cipher_hd_t cipherhd,
char **cache_nonce_addr, const char *hexgrip,
PKT_public_key *pk);
gpg_error_t export_ssh_key (ctrl_t ctrl, const char *userid);
/*-- dearmor.c --*/
int dearmor_file( const char *fname );
int enarmor_file( const char *fname );