Commit 6583d1e7 authored by George Kadianakis's avatar George Kadianakis Committed by David Goulet
Browse files

HSv3: Add subcredential in client auth KDF on the client-side.

parent 1e9428dc
......@@ -1427,13 +1427,15 @@ decrypt_descriptor_cookie(const hs_descriptor_t *desc,
sizeof(desc->superencrypted_data.auth_ephemeral_pubkey)));
tor_assert(!tor_mem_is_zero((char *) client_auth_sk,
sizeof(*client_auth_sk)));
tor_assert(!tor_mem_is_zero((char *) desc->subcredential, DIGEST256_LEN));
/* Calculate x25519(client_x, hs_Y) */
curve25519_handshake(secret_seed, client_auth_sk,
&desc->superencrypted_data.auth_ephemeral_pubkey);
/* Calculate KEYS = KDF(SECRET_SEED, 40) */
/* Calculate KEYS = KDF(subcredential | SECRET_SEED, 40) */
xof = crypto_xof_new();
crypto_xof_add_bytes(xof, desc->subcredential, DIGEST256_LEN);
crypto_xof_add_bytes(xof, secret_seed, sizeof(secret_seed));
crypto_xof_squeeze_bytes(xof, keystream, sizeof(keystream));
crypto_xof_free(xof);
......@@ -2539,9 +2541,8 @@ hs_desc_decode_plaintext(const char *encoded,
}
/* Fully decode an encoded descriptor and set a newly allocated descriptor
* object in desc_out. Subcredentials are used if not NULL else it's ignored.
* Client secret key is used to decrypt the "encrypted" section if not NULL
* else it's ignored.
* object in desc_out. Client secret key is used to decrypt the "encrypted"
* section if not NULL else it's ignored.
*
* Return 0 on success. A negative value is returned on error and desc_out is
* set to NULL. */
......@@ -2558,8 +2559,9 @@ hs_desc_decode_descriptor(const char *encoded,
desc = tor_malloc_zero(sizeof(hs_descriptor_t));
/* Subcredentials are optional. */
if (BUG(!subcredential)) {
/* Subcredentials are not optional. */
if (BUG(!subcredential ||
tor_mem_is_zero((char*)subcredential, DIGEST256_LEN))) {
log_warn(LD_GENERAL, "Tried to decrypt without subcred. Impossible!");
goto err;
}
......
......@@ -303,7 +303,8 @@ link_specifier_t *hs_desc_lspec_to_trunnel(
const hs_desc_link_specifier_t *spec);
hs_desc_authorized_client_t *hs_desc_build_fake_authorized_client(void);
void hs_desc_build_authorized_client(const curve25519_public_key_t *
void hs_desc_build_authorized_client(const uint8_t *subcredential,
const curve25519_public_key_t *
client_auth_pk,
const curve25519_secret_key_t *
auth_ephemeral_sk,
......
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