scd: change_keyattr_from_string for ECC.
NIIBE Yutaka
gniibe at fsij.org
Fri Jul 17 06:07:07 CEST 2015
Hello,
Here is a change for ECC support.
With OpenPGPcard version 3.0, it is possible to change key attribute.
So far, GnuPG's scdaemon only changes the key attribute for RSA when
it's size is different. And that was done during processing
"keytocard" command.
In this change, I deliberately introduce an incompatible change not to
change key attribute during processing "keytocard" command.
I think that it is better for the gpg frontend to have a command
changing key attribute and a user should check if it's correctly
supported.
This change is only scdaemon part. It's comming soon for gpg frontend
part.
Tested with Gnuk. Following commands worked.
$ gpg-connect-agent "SCD SETATTR KEY-ATTR --force 1 19 nistp256" /bye
$ gpg-connect-agent "SCD SETATTR KEY-ATTR --force 2 18 nistp256" /bye
$ gpg-connect-agent "SCD SETATTR KEY-ATTR --force 3 22 ed25519" /bye
diff --git a/scd/app-openpgp.c b/scd/app-openpgp.c
index 1c6d6ec..5ca526c 100644
--- a/scd/app-openpgp.c
+++ b/scd/app-openpgp.c
@@ -57,12 +57,12 @@
#include "options.h"
#include "errors.h"
#include "memory.h"
-#include "util.h"
#include "cardglue.h"
#else /* GNUPG_MAJOR_VERSION != 1 */
#include "scdaemon.h"
#endif /* GNUPG_MAJOR_VERSION != 1 */
+#include "util.h"
#include "i18n.h"
#include "iso7816.h"
#include "app-common.h"
@@ -2818,54 +2818,25 @@ build_ecc_privkey_template (app_t app, int keyno,
/* Helper for do_writekley to change the size of a key. Not ethat
this deletes the entire key without asking. */
static gpg_error_t
-change_keyattr (app_t app, int keyno, unsigned int nbits,
+change_keyattr (app_t app, int keyno, const unsigned char *buf, size_t buflen,
gpg_error_t (*pincb)(void*, const char *, char **),
void *pincb_arg)
{
gpg_error_t err;
- unsigned char *buffer;
- size_t buflen;
- void *relptr;
assert (keyno >=0 && keyno <= 2);
- if (nbits > 4096)
- return gpg_error (GPG_ERR_TOO_LARGE);
-
- /* Read the current attributes into a buffer. */
- relptr = get_one_do (app, 0xC1+keyno, &buffer, &buflen, NULL);
- if (!relptr)
- return gpg_error (GPG_ERR_CARD);
- if (buflen < 6 || buffer[0] != PUBKEY_ALGO_RSA)
- {
- /* Attriutes too short or not an RSA key. */
- xfree (relptr);
- return gpg_error (GPG_ERR_CARD);
- }
-
- /* We only change n_bits and don't touch anything else. Before we
- do so, we round up NBITS to a sensible way in the same way as
- gpg's key generation does it. This may help to sort out problems
- with a few bits too short keys. */
- nbits = ((nbits + 31) / 32) * 32;
- buffer[1] = (nbits >> 8);
- buffer[2] = nbits;
-
/* Prepare for storing the key. */
err = verify_chv3 (app, pincb, pincb_arg);
if (err)
- {
- xfree (relptr);
- return err;
- }
+ return err;
/* Change the attribute. */
- err = iso7816_put_data (app->slot, 0, 0xC1+keyno, buffer, buflen);
- xfree (relptr);
+ err = iso7816_put_data (app->slot, 0, 0xC1+keyno, buf, buflen);
if (err)
- log_error ("error changing size of key %d to %u bits\n", keyno+1, nbits);
+ log_error ("error changing key attribute (key=%d)\n", keyno+1);
else
- log_info ("size of key %d changed to %u bits\n", keyno+1, nbits);
+ log_info ("key attribute changed (key=%d)\n", keyno+1);
flush_cache (app);
parse_algorithm_attribute (app, keyno);
app->did_chv1 = 0;
@@ -2875,18 +2846,21 @@ change_keyattr (app_t app, int keyno, unsigned int nbits,
}
-/* Helper to process an setattr command for name KEY-ATTR. It expects
- a string "--force <keyno> <algo> <nbits>" in (VALUE,VALUELEN). */
+/* Helper to process an setattr command for name KEY-ATTR.
+ In (VALUE,VALUELEN), it expects following string:
+ RSA: "--force <keyno> <algo> <nbits>"
+ ECC: "--force <keyno> <algo> <curvename>"
+ */
static gpg_error_t
change_keyattr_from_string (app_t app,
gpg_error_t (*pincb)(void*, const char *, char **),
void *pincb_arg,
const void *value, size_t valuelen)
{
- gpg_error_t err;
+ gpg_error_t err = 0;
char *string;
int keyno, algo;
- unsigned int nbits;
+ int n = 0;
/* VALUE is expected to be a string but not guaranteed to be
terminated. Thus copy it to an allocated buffer first. */
@@ -2899,17 +2873,91 @@ change_keyattr_from_string (app_t app,
/* Because this function deletes the key we require the string
"--force" in the data to make clear that something serious might
happen. */
- if (sscanf (string, " --force %d %d %u", &keyno, &algo, &nbits) != 3)
- err = gpg_error (GPG_ERR_INV_DATA);
- else if (keyno < 1 || keyno > 3)
+ sscanf (string, " --force %d %d %n", &keyno, &algo, &n);
+ if (n < 13)
+ {
+ err = gpg_error (GPG_ERR_INV_DATA);
+ goto leave;
+ }
+
+ if (keyno < 1 || keyno > 3)
err = gpg_error (GPG_ERR_INV_ID);
- else if (algo != PUBKEY_ALGO_RSA)
- err = gpg_error (GPG_ERR_PUBKEY_ALGO);
- else if (nbits < 1024)
- err = gpg_error (GPG_ERR_TOO_SHORT);
+ else if (algo == PUBKEY_ALGO_RSA)
+ {
+ unsigned int nbits;
+
+ errno = 0;
+ nbits = strtoul (string+n, NULL, 10);
+ if (errno)
+ err = gpg_error (GPG_ERR_INV_DATA);
+ else if (nbits < 1024)
+ err = gpg_error (GPG_ERR_TOO_SHORT);
+ else if (nbits > 4096)
+ err = gpg_error (GPG_ERR_TOO_LARGE);
+ else
+ {
+ unsigned char *buf;
+ size_t buflen;
+ void *relptr;
+
+ /* Read the current attributes into a buffer. */
+ relptr = get_one_do (app, 0xC1+keyno, &buf, &buflen, NULL);
+ if (!relptr)
+ {
+ err = gpg_error (GPG_ERR_CARD);
+ goto leave;
+ }
+ if (buflen < 6 || buf[0] != PUBKEY_ALGO_RSA)
+ {
+ /* Attriutes too short or not an RSA key. */
+ xfree (relptr);
+ err = gpg_error (GPG_ERR_CARD);
+ goto leave;
+ }
+
+ /* We only change n_bits and don't touch anything else. Before we
+ do so, we round up NBITS to a sensible way in the same way as
+ gpg's key generation does it. This may help to sort out problems
+ with a few bits too short keys. */
+ nbits = ((nbits + 31) / 32) * 32;
+ buf[1] = (nbits >> 8);
+ buf[2] = nbits;
+ err = change_keyattr (app, keyno-1, buf, buflen, pincb, pincb_arg);
+ xfree (relptr);
+ }
+ }
+ else if (algo == PUBKEY_ALGO_ECDH || algo == PUBKEY_ALGO_ECDSA
+ || algo == PUBKEY_ALGO_EDDSA)
+ {
+ const char *oidstr;
+
+ oidstr = openpgp_curve_to_oid (string+n, NULL);
+ if (!oidstr)
+ err = gpg_error (GPG_ERR_INV_DATA);
+ else
+ {
+ gcry_mpi_t m;
+
+ err = openpgp_oid_from_str (oidstr, &m);
+ if (!err)
+ {
+ unsigned int len;
+ const unsigned char *buf = gcry_mpi_get_opaque (m, &len);
+
+ /* We have enough room at STRING. */
+ len = buf[0];
+ string[0] = algo;
+ memcpy (string+1, buf+1, len++);
+ err = change_keyattr (app, keyno-1, string, len,
+ pincb, pincb_arg);
+ gcry_mpi_release (m);
+ }
+ }
+ }
else
- err = change_keyattr (app, keyno-1, nbits, pincb, pincb_arg);
+ err = gpg_error (GPG_ERR_PUBKEY_ALGO);
+ leave:
xfree (string);
return err;
}
@@ -3032,14 +3080,6 @@ rsa_writekey (app_t app, gpg_error_t (*pincb)(void*, const char *, char **),
if (opt.verbose)
log_info ("RSA modulus size is %u bits (%u bytes)\n",
nbits, (unsigned int)rsa_n_len);
- if (nbits && nbits != maxbits
- && app->app_local->extcap.algo_attr_change)
- {
- /* Try to switch the key to a new length. */
- err = change_keyattr (app, keyno, nbits, pincb, pincb_arg);
- if (!err)
- maxbits = app->app_local->keyattr[keyno].rsa.n_bits;
- }
if (nbits != maxbits)
{
log_error (_("RSA modulus missing or not of size %d bits\n"),
--
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