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gnupg/common/ssh-utils.c
Werner Koch b4cb20cfc3 ssh: Support ECDSA keys.
* agent/command-ssh.c (SPEC_FLAG_IS_ECDSA): New.
(struct ssh_key_type_spec): Add fields CURVE_NAME and HASH_ALGO.
(ssh_key_types): Add types ecdsa-sha2-nistp{256,384,521}.
(ssh_signature_encoder_t): Add arg spec and adjust all callers.
(ssh_signature_encoder_ecdsa): New.
(sexp_key_construct, sexp_key_extract, ssh_receive_key)
(ssh_convert_key_to_blob): Support ecdsa.
(ssh_identifier_from_curve_name): New.
(ssh_send_key_public): Retrieve and pass the curve_name.
(key_secret_to_public): Ditto.
(data_sign): Add arg SPEC and change callers to pass it.
(ssh_handler_sign_request): Get the hash algo from SPEC.
* common/ssh-utils.c (get_fingerprint): Support ecdsa.

* agent/protect.c (protect_info): Add flag ECC_HACK.
(agent_protect): Allow the use of the "curve" parameter.
* agent/t-protect.c (test_agent_protect): Add a test case for ecdsa.

* agent/command-ssh.c (ssh_key_grip): Print a better error code.
--

The 3 standard curves are now supported in gpg-agent's ssh-agent
protocol implementation.  I tested this with all 3 curves and keys
generated by OpenSSH 5.9p1.

Using existing non-ssh generated keys will likely fail for now. To fix
this, the code should first undergo some more cleanup; then the fixes
are pretty straightforward.  And yes, the data structures are way too
complicated.

(cherry picked from commit 649b31c663b8674bc874b4ef283d714a13dc8cfe)

Solved conflicts:

	agent/protect.c
	agent/t-protect.c
        common/ssh-utils.c (different variabale name)
2013-07-01 20:31:16 +02:00

216 lines
6.0 KiB
C

/* ssh-utils.c - Secure Shell helper functions
* Copyright (C) 2011 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include <assert.h>
#include "util.h"
#include "ssh-utils.h"
/* Return the Secure Shell type fingerprint for KEY. The length of
the fingerprint is returned at R_LEN and the fingerprint itself at
R_FPR. In case of a error code is returned and NULL stored at
R_FPR. This function is usually called via the ssh_get_fingerprint
macro which makes sure to use the correct value for ERRSOURCE. */
static gpg_error_t
get_fingerprint (gcry_sexp_t key, void **r_fpr, size_t *r_len,
gpg_err_source_t errsource, int as_string)
{
gpg_error_t err;
gcry_sexp_t list = NULL;
gcry_sexp_t l2 = NULL;
const char *s;
char *name = NULL;
int idx;
const char *elems;
gcry_md_hd_t md = NULL;
*r_fpr = NULL;
*r_len = 0;
/* Check that the first element is valid. */
list = gcry_sexp_find_token (key, "public-key", 0);
if (!list)
list = gcry_sexp_find_token (key, "private-key", 0);
if (!list)
list = gcry_sexp_find_token (key, "protected-private-key", 0);
if (!list)
list = gcry_sexp_find_token (key, "shadowed-private-key", 0);
if (!list)
{
err = gpg_err_make (errsource, GPG_ERR_UNKNOWN_SEXP);
goto leave;
}
l2 = gcry_sexp_cadr (list);
gcry_sexp_release (list);
list = l2;
l2 = NULL;
name = gcry_sexp_nth_string (list, 0);
if (!name)
{
err = gpg_err_make (errsource, GPG_ERR_INV_SEXP);
goto leave;
}
err = gcry_md_open (&md, GCRY_MD_MD5, 0);
if (err)
goto leave;
switch (gcry_pk_map_name (name))
{
case GCRY_PK_RSA:
elems = "en";
gcry_md_write (md, "\0\0\0\x07ssh-rsa", 11);
break;
case GCRY_PK_DSA:
elems = "pqgy";
gcry_md_write (md, "\0\0\0\x07ssh-dss", 11);
break;
case GCRY_PK_ECDSA:
/* We only support the 3 standard curves for now. It is just a
quick hack. */
elems = "q";
gcry_md_write (md, "\0\0\0\x13" "ecdsa-sha2-nistp", 20);
l2 = gcry_sexp_find_token (list, "curve", 0);
if (!l2)
elems = "";
else
{
gcry_free (name);
name = gcry_sexp_nth_string (l2, 1);
gcry_sexp_release (l2);
l2 = NULL;
if (!name)
elems = "";
else if (!strcmp (name, "NIST P-256") || !strcmp (name, "nistp256"))
gcry_md_write (md, "256\0\0\0\x08nistp256", 15);
else if (!strcmp (name, "NIST P-384") || !strcmp (name, "nistp384"))
gcry_md_write (md, "384\0\0\0\x08nistp521", 15);
else if (!strcmp (name, "NIST P-521") || !strcmp (name, "nistp521"))
gcry_md_write (md, "521\0\0\0\x08nistp521", 15);
else
elems = "";
}
if (!*elems)
err = gpg_err_make (errsource, GPG_ERR_UNKNOWN_CURVE);
break;
default:
elems = "";
err = gpg_err_make (errsource, GPG_ERR_PUBKEY_ALGO);
break;
}
if (err)
goto leave;
for (idx = 0, s = elems; *s; s++, idx++)
{
gcry_mpi_t a;
unsigned char *buf;
size_t buflen;
l2 = gcry_sexp_find_token (list, s, 1);
if (!l2)
{
err = gpg_err_make (errsource, GPG_ERR_INV_SEXP);
goto leave;
}
a = gcry_sexp_nth_mpi (l2, 1, GCRYMPI_FMT_USG);
gcry_sexp_release (l2);
l2 = NULL;
if (!a)
{
err = gpg_err_make (errsource, GPG_ERR_INV_SEXP);
goto leave;
}
err = gcry_mpi_aprint (GCRYMPI_FMT_SSH, &buf, &buflen, a);
gcry_mpi_release (a);
if (err)
goto leave;
gcry_md_write (md, buf, buflen);
gcry_free (buf);
}
*r_fpr = gcry_malloc (as_string? 61:20);
if (!*r_fpr)
{
err = gpg_err_make (errsource, gpg_err_code_from_syserror ());
goto leave;
}
if (as_string)
{
bin2hexcolon (gcry_md_read (md, GCRY_MD_MD5), 16, *r_fpr);
*r_len = 3*16+1;
strlwr (*r_fpr);
}
else
{
memcpy (*r_fpr, gcry_md_read (md, GCRY_MD_MD5), 16);
*r_len = 16;
}
err = 0;
leave:
gcry_free (name);
gcry_sexp_release (l2);
gcry_md_close (md);
gcry_sexp_release (list);
return err;
}
/* Return the Secure Shell type fingerprint for KEY. The length of
the fingerprint is returned at R_LEN and the fingerprint itself at
R_FPR. In case of an error an error code is returned and NULL
stored at R_FPR. This function is usually called via the
ssh_get_fingerprint macro which makes sure to use the correct value
for ERRSOURCE. */
gpg_error_t
_ssh_get_fingerprint (gcry_sexp_t key, void **r_fpr, size_t *r_len,
gpg_err_source_t errsource)
{
return get_fingerprint (key, r_fpr, r_len, errsource, 0);
}
/* Return the Secure Shell type fingerprint for KEY as a string. The
fingerprint is mallcoed and stored at R_FPRSTR. In case of an
error an error code is returned and NULL stored at R_FPRSTR. This
function is usually called via the ssh_get_fingerprint_string macro
which makes sure to use the correct value for ERRSOURCE. */
gpg_error_t
_ssh_get_fingerprint_string (gcry_sexp_t key, char **r_fprstr,
gpg_err_source_t errsource)
{
gpg_error_t err;
size_t dummy;
void *string;
err = get_fingerprint (key, &string, &dummy, errsource, 1);
*r_fprstr = string;
return err;
}