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ecdh: Use gcry_md_read when KDF API is not available. 

* g10/ecdh.c [GCRYPT_VERSION_NUMBER] (derive_kek): Conditionalize.

--

Note that it's compile-time check.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka 2022-07-05 13:23:44 +09:00
parent c281bd9434
commit 219494c07b
1 changed files with 22 additions and 0 deletions
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22
g10/ecdh.c
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@ -189,6 +189,7 @@ derive_kek (size_t kek_size,
const unsigned char *kdf_params, size_t kdf_params_size)
{
gpg_error_t err;
#if GCRYPT_VERSION_NUMBER >= 0x010b00
gcry_kdf_hd_t hd;
unsigned long param[1];
@ -205,6 +206,27 @@ derive_kek (size_t kek_size,
/* Clean the tail before returning. */
memset (secret_x+kek_size, 0, secret_x_size - kek_size);
}
#else
gcry_md_hd_t h;
log_assert( gcry_md_get_algo_dlen (kdf_hash_algo) >= 32 );
err = gcry_md_open (&h, kdf_hash_algo, 0);
if (err)
{
log_error ("gcry_md_open failed for kdf_hash_algo %d: %s",
kdf_hash_algo, gpg_strerror (err));
return err;
}
gcry_md_write(h, "\x00\x00\x00\x01", 4); /* counter = 1 */
gcry_md_write(h, secret_x, secret_x_size); /* x of the point X */
gcry_md_write(h, kdf_params, kdf_params_size); /* KDF parameters */
gcry_md_final (h);
memcpy (secret_x, gcry_md_read (h, kdf_hash_algo), kek_size);
gcry_md_close (h);
/* Clean the tail before returning. */
memset (secret_x+kek_size, 0, secret_x_size - kek_size);
#endif
if (DBG_CRYPTO)
log_printhex (secret_x, kek_size, "ecdh KEK is:");
return err;