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agent: For ECC, use opaque MPI for key representation. 

* agent/cvt-openpgp.c (scan_pgp_format): New with SOS support.
(do_unprotect): Use scan_pgp_format, handle opaque MPI for ECC.
(convert_from_openpgp_main): Use opaque MPI for ECC.
(apply_protection): Set GCRYMPI_FLAG_USER1 flag for encrypted secret.
(extract_private_key): Use "/qd" for ECC, opaque MPI.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka 2020-06-05 10:09:05 +09:00
parent a7d46c78e2
commit 2b11851624
1 changed files with 69 additions and 20 deletions
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89
agent/cvt-openpgp.c
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@ -374,6 +374,38 @@ prepare_unprotect (int pubkey_algo, gcry_mpi_t *skey, size_t skeysize,
}
/* Scan octet string in the PGP format (length-in-two-octet octets) */
static int
scan_pgp_format (gcry_mpi_t *r_mpi, int pubkey_algo,
const unsigned char *buffer,
size_t buflen, size_t *r_nbytes)
{
/* Using gcry_mpi_scan with GCRYMPI_FLAG_PGP can be used if it is
MPI, but it will be "normalized" removing leading zeros. */
unsigned int nbits, nbytes;
if (pubkey_algo != GCRY_PK_ECC)
return gcry_mpi_scan (r_mpi, GCRYMPI_FMT_PGP, buffer, buflen, r_nbytes);
/* It's ECC, where we use SOS. */
if (buflen < 2)
return GPG_ERR_INV_OBJ;
nbits = (buffer[0] << 8) | buffer[1];
if (nbits >= 16384)
return GPG_ERR_INV_OBJ;
nbytes = (nbits + 7) / 8;
if (buflen < nbytes + 2)
return GPG_ERR_INV_OBJ;
*r_nbytes = nbytes + 2;
*r_mpi = gcry_mpi_set_opaque_copy (NULL, buffer+2, nbits);
return 0;
}
/* Note that this function modifies SKEY. SKEYSIZE is the allocated
size of the array including the NULL item; this is used for a
bounds check. On success a converted key is stored at R_KEY. */
@ -407,29 +439,43 @@ do_unprotect (const char *passphrase,
actual_csum = 0;
for (i=npkey; i < nskey; i++)
{
unsigned char *buffer;
if (!skey[i] || gcry_mpi_get_flag (skey[i], GCRYMPI_FLAG_USER1))
return gpg_error (GPG_ERR_BAD_SECKEY);
if (gcry_mpi_get_flag (skey[i], GCRYMPI_FLAG_OPAQUE))
{
unsigned int nbits;
const unsigned char *buffer;
buffer = gcry_mpi_get_opaque (skey[i], &nbits);
nbytes = (nbits+7)/8;
nbits = nbytes * 8;
if (*buffer)
if (nbits >= 8 && !(*buffer & 0x80))
if (--nbits >= 7 && !(*buffer & 0x40))
if (--nbits >= 6 && !(*buffer & 0x20))
if (--nbits >= 5 && !(*buffer & 0x10))
if (--nbits >= 4 && !(*buffer & 0x08))
if (--nbits >= 3 && !(*buffer & 0x04))
if (--nbits >= 2 && !(*buffer & 0x02))
if (--nbits >= 1 && !(*buffer & 0x01))
--nbits;
actual_csum += (nbits >> 8);
actual_csum += (nbits & 0xff);
actual_csum += checksum (buffer, nbytes);
}
else
{
unsigned char *buffer;
err = gcry_mpi_aprint (GCRYMPI_FMT_PGP, &buffer, &nbytes,
skey[i]);
if (!err)
actual_csum += checksum (buffer, nbytes);
if (err)
return err;
actual_csum += checksum (buffer, nbytes);
xfree (buffer);
}
if (err)
return err;
}
if (actual_csum != desired_csum)
@ -487,7 +533,7 @@ do_unprotect (const char *passphrase,
unsigned char *data;
u16 csum_pgp7 = 0;
if (!gcry_mpi_get_flag (skey[npkey], GCRYMPI_FLAG_OPAQUE ))
if (!gcry_mpi_get_flag (skey[npkey], GCRYMPI_FLAG_USER1))
{
gcry_cipher_close (cipher_hd);
return gpg_error (GPG_ERR_BAD_SECKEY);
@ -556,7 +602,7 @@ do_unprotect (const char *passphrase,
{
for (i=npkey; i < nskey; i++ )
{
if (gcry_mpi_scan (&tmpmpi, GCRYMPI_FMT_PGP, p, ndata, &nbytes))
if (scan_pgp_format (&tmpmpi, pubkey_algo, p, ndata, &nbytes))
{
/* Checksum was okay, but not correctly decrypted. */
desired_csum = 0;
@ -587,7 +633,7 @@ do_unprotect (const char *passphrase,
size_t ndata;
unsigned int ndatabits;
if (!skey[i] || !gcry_mpi_get_flag (skey[i], GCRYMPI_FLAG_OPAQUE))
if (!skey[i] || !gcry_mpi_get_flag (skey[i], GCRYMPI_FLAG_USER1))
{
gcry_cipher_close (cipher_hd);
return gpg_error (GPG_ERR_BAD_SECKEY);
@ -614,7 +660,7 @@ do_unprotect (const char *passphrase,
buffer[1] = p[1];
gcry_cipher_decrypt (cipher_hd, buffer+2, ndata-2, p+2, ndata-2);
actual_csum += checksum (buffer, ndata);
err = gcry_mpi_scan (&tmpmpi, GCRYMPI_FMT_PGP, buffer, ndata, &ndata);
err = scan_pgp_format (&tmpmpi, pubkey_algo, buffer, ndata, &nbytes);
xfree (buffer);
if (err)
{
@ -837,13 +883,14 @@ convert_from_openpgp_main (ctrl_t ctrl, gcry_sexp_t s_pgp, int dontcare_exist,
value = gcry_sexp_nth_data (list, ++idx, &valuelen);
if (!value || !valuelen)
goto bad_seckey;
if (is_enc)
if (is_enc || npkey == 1 /* This is ECC */)
{
/* Encrypted parameters need to be stored as opaque. */
skey[skeyidx] = gcry_mpi_set_opaque_copy (NULL, value, valuelen*8);
if (!skey[skeyidx])
goto outofmem;
gcry_mpi_set_flag (skey[skeyidx], GCRYMPI_FLAG_USER1);
if (is_enc)
/* Encrypted parameters need to have a USER1 flag. */
gcry_mpi_set_flag (skey[skeyidx], GCRYMPI_FLAG_USER1);
}
else
{
@ -1171,6 +1218,7 @@ apply_protection (gcry_mpi_t *array, int npkey, int nskey,
array[i] = NULL;
}
array[npkey] = gcry_mpi_set_opaque (NULL, data, ndata*8);
gcry_mpi_set_flag (array[npkey], GCRYMPI_FLAG_USER1);
return 0;
}
@ -1199,7 +1247,7 @@ extract_private_key (gcry_sexp_t s_key, int req_private_key_data,
gpg_error_t err;
gcry_sexp_t list, l2;
char *name;
const char *algoname, *format;
const char *algoname, *format, *elems;
int npkey, nskey;
gcry_sexp_t curve = NULL;
gcry_sexp_t flags = NULL;
@ -1244,7 +1292,7 @@ extract_private_key (gcry_sexp_t s_key, int req_private_key_data,
if (!strcmp (name, "rsa"))
{
algoname = "rsa";
format = "ned?p?q?u?";
format = elems = "ned?p?q?u?";
npkey = 2;
nskey = 6;
err = gcry_sexp_extract_param (list, NULL, format,
@ -1254,7 +1302,7 @@ extract_private_key (gcry_sexp_t s_key, int req_private_key_data,
else if (!strcmp (name, "elg"))
{
algoname = "elg";
format = "pgyx?";
format = elems = "pgyx?";
npkey = 3;
nskey = 4;
err = gcry_sexp_extract_param (list, NULL, format,
@ -1264,7 +1312,7 @@ extract_private_key (gcry_sexp_t s_key, int req_private_key_data,
else if (!strcmp (name, "dsa"))
{
algoname = "dsa";
format = "pqgyx?";
format = elems = "pqgyx?";
npkey = 4;
nskey = 5;
err = gcry_sexp_extract_param (list, NULL, format,
@ -1274,7 +1322,8 @@ extract_private_key (gcry_sexp_t s_key, int req_private_key_data,
else if (!strcmp (name, "ecc") || !strcmp (name, "ecdsa"))
{
algoname = "ecc";
format = "qd?";
format = "/qd?";
elems = "qd?";
npkey = 1;
nskey = 2;
curve = gcry_sexp_find_token (list, "curve", 0);
@ -1298,7 +1347,7 @@ extract_private_key (gcry_sexp_t s_key, int req_private_key_data,
{
*r_algoname = algoname;
if (r_elems)
*r_elems = format;
*r_elems = elems;
*r_npkey = npkey;
if (r_nskey)
*r_nskey = nskey;