gpg: Clean up ECDH code path (5).

* g10/ecdh.c (pk_ecdh_encrypt_with_shared_point): Now, it's only for
encrytion.
(pk_ecdh_decrypt): Use prepare_ecdh_with_shared_point and move decrypt
code path in original pk_ecdh_encrypt_with_shared_point here.
* g10/pkglue.h (pk_ecdh_encrypt_with_shared_point): Change API.
* g10/pkglue.c (pk_encrypt): Follow the change.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka 2020-05-22 11:58:21 +09:00
parent 64d93271bf
commit 510bda7d37
3 changed files with 141 additions and 122 deletions

View File

@ -330,15 +330,14 @@ prepare_ecdh_with_shared_point (gcry_mpi_t shared_mpi,
return err;
}
/* Encrypts/decrypts DATA using a key derived from the ECC shared
point SHARED_MPI using the FIPS SP 800-56A compliant method
key_derivation+key_wrapping. If IS_ENCRYPT is true the function
encrypts; if false, it decrypts. PKEY is the public key and PK_FP
the fingerprint of this public key. On success the result is
stored at R_RESULT; on failure NULL is stored at R_RESULT and an
error code returned. */
/* Encrypts DATA using a key derived from the ECC shared point
SHARED_MPI using the FIPS SP 800-56A compliant method
key_derivation+key_wrapping. PKEY is the public key and PK_FP the
fingerprint of this public key. On success the result is stored at
R_RESULT; on failure NULL is stored at R_RESULT and an error code
returned. */
gpg_error_t
pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
pk_ecdh_encrypt_with_shared_point (gcry_mpi_t shared_mpi,
const byte pk_fp[MAX_FINGERPRINT_LEN],
gcry_mpi_t data, gcry_mpi_t *pkey,
gcry_mpi_t *r_result)
@ -349,6 +348,7 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
byte *data_buf;
int data_buf_size;
gcry_mpi_t result;
byte *in;
*r_result = NULL;
@ -357,7 +357,7 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
return err;
data_buf_size = (gcry_mpi_get_nbits(data)+7)/8;
if ((data_buf_size & 7) != (is_encrypt ? 0 : 1))
if ((data_buf_size & 7) != 0)
{
log_error ("can't use a shared secret of %d bytes for ecdh\n",
data_buf_size);
@ -373,117 +373,50 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
return err;
}
if (is_encrypt)
in = data_buf+1+data_buf_size+8;
/* Write data MPI into the end of data_buf. data_buf is size
aeswrap data. */
err = gcry_mpi_print (GCRYMPI_FMT_USG, in,
data_buf_size, &nbytes, data/*in*/);
if (err)
{
byte *in = data_buf+1+data_buf_size+8;
/* Write data MPI into the end of data_buf. data_buf is size
aeswrap data. */
err = gcry_mpi_print (GCRYMPI_FMT_USG, in,
data_buf_size, &nbytes, data/*in*/);
if (err)
{
log_error ("ecdh failed to export DEK: %s\n", gpg_strerror (err));
gcry_cipher_close (hd);
xfree (data_buf);
return err;
}
if (DBG_CRYPTO)
log_printhex (in, data_buf_size, "ecdh encrypting :");
err = gcry_cipher_encrypt (hd, data_buf+1, data_buf_size+8,
in, data_buf_size);
memset (in, 0, data_buf_size);
log_error ("ecdh failed to export DEK: %s\n", gpg_strerror (err));
gcry_cipher_close (hd);
if (err)
{
log_error ("ecdh failed in gcry_cipher_encrypt: %s\n",
gpg_strerror (err));
xfree (data_buf);
return err;
}
data_buf[0] = data_buf_size+8;
if (DBG_CRYPTO)
log_printhex (data_buf+1, data_buf[0], "ecdh encrypted to:");
result = gcry_mpi_set_opaque (NULL, data_buf, 8 * (1+data_buf[0]));
if (!result)
{
err = gpg_error_from_syserror ();
xfree (data_buf);
log_error ("ecdh failed to create an MPI: %s\n",
gpg_strerror (err));
return err;
}
*r_result = result;
}
else
{
byte *in;
const void *p;
unsigned int nbits;
p = gcry_mpi_get_opaque (data, &nbits);
nbytes = (nbits+7)/8;
if (!p || nbytes > data_buf_size || !nbytes)
{
xfree (data_buf);
gcry_cipher_close (hd);
return gpg_error (GPG_ERR_BAD_MPI);
}
memcpy (data_buf, p, nbytes);
if (data_buf[0] != nbytes-1)
{
log_error ("ecdh inconsistent size\n");
xfree (data_buf);
gcry_cipher_close (hd);
return gpg_error (GPG_ERR_BAD_MPI);
}
in = data_buf+data_buf_size;
data_buf_size = data_buf[0];
if (DBG_CRYPTO)
log_printhex (data_buf+1, data_buf_size, "ecdh decrypting :");
err = gcry_cipher_decrypt (hd, in, data_buf_size, data_buf+1,
data_buf_size);
gcry_cipher_close (hd);
if (err)
{
log_error ("ecdh failed in gcry_cipher_decrypt: %s\n",
gpg_strerror (err));
xfree (data_buf);
return err;
}
data_buf_size -= 8;
if (DBG_CRYPTO)
log_printhex (in, data_buf_size, "ecdh decrypted to :");
/* Padding is removed later. */
/* if (in[data_buf_size-1] > 8 ) */
/* { */
/* log_error ("ecdh failed at decryption: invalid padding." */
/* " 0x%02x > 8\n", in[data_buf_size-1] ); */
/* return gpg_error (GPG_ERR_BAD_KEY); */
/* } */
err = gcry_mpi_scan (&result, GCRYMPI_FMT_USG, in, data_buf_size, NULL);
xfree (data_buf);
if (err)
{
log_error ("ecdh failed to create a plain text MPI: %s\n",
gpg_strerror (err));
return err;
}
*r_result = result;
return err;
}
if (DBG_CRYPTO)
log_printhex (in, data_buf_size, "ecdh encrypting :");
err = gcry_cipher_encrypt (hd, data_buf+1, data_buf_size+8,
in, data_buf_size);
memset (in, 0, data_buf_size);
gcry_cipher_close (hd);
if (err)
{
log_error ("ecdh failed in gcry_cipher_encrypt: %s\n",
gpg_strerror (err));
xfree (data_buf);
return err;
}
data_buf[0] = data_buf_size+8;
if (DBG_CRYPTO)
log_printhex (data_buf+1, data_buf[0], "ecdh encrypted to:");
result = gcry_mpi_set_opaque (NULL, data_buf, 8 * (1+data_buf[0]));
if (!result)
{
err = gpg_error_from_syserror ();
xfree (data_buf);
log_error ("ecdh failed to create an MPI: %s\n",
gpg_strerror (err));
return err;
}
*r_result = result;
return err;
}
@ -538,12 +471,98 @@ pk_ecdh_generate_ephemeral_key (gcry_mpi_t *pkey, gcry_mpi_t *r_k)
/* Perform ECDH decryption. */
int
pk_ecdh_decrypt (gcry_mpi_t * result, const byte sk_fp[MAX_FINGERPRINT_LEN],
gcry_mpi_t data, gcry_mpi_t shared, gcry_mpi_t * skey)
pk_ecdh_decrypt (gcry_mpi_t *r_result, const byte sk_fp[MAX_FINGERPRINT_LEN],
gcry_mpi_t data, gcry_mpi_t shared_mpi, gcry_mpi_t * skey)
{
gpg_error_t err;
gcry_cipher_hd_t hd;
size_t nbytes;
byte *data_buf;
int data_buf_size;
byte *in;
const void *p;
unsigned int nbits;
if (!data)
return gpg_error (GPG_ERR_BAD_MPI);
return pk_ecdh_encrypt_with_shared_point (0 /*=decryption*/, shared,
sk_fp, data/*encr data as an MPI*/,
skey, result);
*r_result = NULL;
err = prepare_ecdh_with_shared_point (shared_mpi, sk_fp, skey, &hd);
if (err)
return err;
data_buf_size = (gcry_mpi_get_nbits(data)+7)/8;
if ((data_buf_size & 7) != 1)
{
log_error ("can't use a shared secret of %d bytes for ecdh\n",
data_buf_size);
gcry_cipher_close (hd);
return gpg_error (GPG_ERR_BAD_DATA);
}
data_buf = xtrymalloc_secure( 1 + 2*data_buf_size + 8);
if (!data_buf)
{
err = gpg_error_from_syserror ();
gcry_cipher_close (hd);
return err;
}
p = gcry_mpi_get_opaque (data, &nbits);
nbytes = (nbits+7)/8;
if (!p || nbytes > data_buf_size || !nbytes)
{
xfree (data_buf);
gcry_cipher_close (hd);
return gpg_error (GPG_ERR_BAD_MPI);
}
memcpy (data_buf, p, nbytes);
if (data_buf[0] != nbytes-1)
{
log_error ("ecdh inconsistent size\n");
xfree (data_buf);
gcry_cipher_close (hd);
return gpg_error (GPG_ERR_BAD_MPI);
}
in = data_buf+data_buf_size;
data_buf_size = data_buf[0];
if (DBG_CRYPTO)
log_printhex (data_buf+1, data_buf_size, "ecdh decrypting :");
err = gcry_cipher_decrypt (hd, in, data_buf_size, data_buf+1,
data_buf_size);
gcry_cipher_close (hd);
if (err)
{
log_error ("ecdh failed in gcry_cipher_decrypt: %s\n",
gpg_strerror (err));
xfree (data_buf);
return err;
}
data_buf_size -= 8;
if (DBG_CRYPTO)
log_printhex (in, data_buf_size, "ecdh decrypted to :");
/* Padding is removed later. */
/* if (in[data_buf_size-1] > 8 ) */
/* { */
/* log_error ("ecdh failed at decryption: invalid padding." */
/* " 0x%02x > 8\n", in[data_buf_size-1] ); */
/* return gpg_error (GPG_ERR_BAD_KEY); */
/* } */
err = gcry_mpi_scan (r_result, GCRYMPI_FMT_USG, in, data_buf_size, NULL);
xfree (data_buf);
if (err)
{
log_error ("ecdh failed to create a plain text MPI: %s\n",
gpg_strerror (err));
return err;
}
return err;
}

View File

@ -330,7 +330,7 @@ pk_encrypt (pubkey_algo_t algo, gcry_mpi_t *resarr, gcry_mpi_t data,
if (fpn != 20)
rc = gpg_error (GPG_ERR_INV_LENGTH);
else
rc = pk_ecdh_encrypt_with_shared_point (1 /*=encrypton*/, shared,
rc = pk_ecdh_encrypt_with_shared_point (shared,
fp, data, pkey, &result);
gcry_mpi_release (shared);
if (!rc)

View File

@ -36,7 +36,7 @@ int pk_check_secret_key (pubkey_algo_t algo, gcry_mpi_t *skey);
gcry_mpi_t pk_ecdh_default_params (unsigned int qbits);
gpg_error_t pk_ecdh_generate_ephemeral_key (gcry_mpi_t *pkey, gcry_mpi_t *r_k);
gpg_error_t pk_ecdh_encrypt_with_shared_point
/* */ (int is_encrypt, gcry_mpi_t shared_mpi,
/* */ (gcry_mpi_t shared_mpi,
const byte pk_fp[MAX_FINGERPRINT_LEN],
gcry_mpi_t data, gcry_mpi_t *pkey,
gcry_mpi_t *out);