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gpg: Clean up ECDH code path (4).

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* g10/ecdh.c (prepare_ecdh_with_shared_point): New.
(pk_ecdh_encrypt_with_shared_point): Fixing error paths for closing
the cipher handle, use prepare_ecdh_with_shared_point.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka 2020-05-22 11:44:36 +09:00
parent 80c02d13d9
commit 64d93271bf
1 changed files with 165 additions and 146 deletions
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67
g10/ecdh.c
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@ -209,19 +209,13 @@ derive_kek (size_t kek_size,
}
/* 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. */
gpg_error_t
pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
/* Prepare ECDH using SHARED_MPI, PK_FP fingerprint, and PKEY array.
Returns the cipher handle in R_HD, which needs to be closed by
the caller. */
static gpg_error_t
prepare_ecdh_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)
gcry_mpi_t *pkey, gcry_cipher_hd_t *r_hd)
{
gpg_error_t err;
byte *secret_x;
@ -234,8 +228,9 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
unsigned char kdf_params[256];
size_t kdf_params_size;
size_t kek_size;
gcry_cipher_hd_t hd;
*r_result = NULL;
*r_hd = NULL;
if (!gcry_mpi_get_flag (pkey[2], GCRYMPI_FLAG_OPAQUE))
return gpg_error (GPG_ERR_BUG);
@ -311,15 +306,6 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
}
/* And, finally, aeswrap with key secret_x. */
{
gcry_cipher_hd_t hd;
size_t nbytes;
byte *data_buf;
int data_buf_size;
gcry_mpi_t result;
err = gcry_cipher_open (&hd, kdf_encr_algo, GCRY_CIPHER_MODE_AESWRAP, 0);
if (err)
{
@ -337,14 +323,45 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
gcry_cipher_close (hd);
log_error ("ecdh failed in gcry_cipher_setkey: %s\n",
gpg_strerror (err));
return err;
}
else
*r_hd = hd;
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. */
gpg_error_t
pk_ecdh_encrypt_with_shared_point (int is_encrypt, 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)
{
gpg_error_t err;
gcry_cipher_hd_t hd;
size_t nbytes;
byte *data_buf;
int data_buf_size;
gcry_mpi_t result;
*r_result = NULL;
err = prepare_ecdh_with_shared_point (shared_mpi, pk_fp, pkey, &hd);
if (err)
return err;
data_buf_size = (gcry_mpi_get_nbits(data)+7)/8;
if ((data_buf_size & 7) != (is_encrypt ? 0 : 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);
}
@ -407,12 +424,14 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
{
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);
@ -420,6 +439,7 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
{
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;
@ -463,7 +483,6 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
*r_result = result;
}
}
return err;
}