commit ba928e1ac8f13714aa6b619dd6f12ae89240d6ff Author: George Kadianakis desnacked@riseup.net Date: Tue May 2 16:18:10 2017 +0300
Refactor the HS ntor key expansion to fit the e2e circuit API.
We want to use the circuit_init_cpath_crypto() function to setup our cpath, and that function accepts a key array as input. So let's make our HS ntor key expansion function also return a key array as output, instead of a struct.
Also, we actually don't need KH from the key expansion, so the key expansion output can be one DIGEST256_LEN shorter. See here for more info: https://trac.torproject.org/projects/tor/ticket/22052#comment:3 --- src/or/hs_ntor.c | 39 +++++++++------------------------------ src/or/hs_ntor.h | 23 ++++++----------------- 2 files changed, 15 insertions(+), 47 deletions(-)
diff --git a/src/or/hs_ntor.c b/src/or/hs_ntor.c index 1198998..668ef22 100644 --- a/src/or/hs_ntor.c +++ b/src/or/hs_ntor.c @@ -578,49 +578,28 @@ hs_ntor_client_rendezvous2_mac_is_good(
/* Input length to KDF for key expansion */ #define NTOR_KEY_EXPANSION_KDF_INPUT_LEN (DIGEST256_LEN + M_HSEXPAND_LEN) -/* Output length of KDF for key expansion */ -#define NTOR_KEY_EXPANSION_KDF_OUTPUT_LEN (DIGEST256_LEN*3+CIPHER256_KEY_LEN*2) - -/** Given the rendezvous key material in <b>hs_ntor_rend_cell_keys</b>, do the - * circuit key expansion as specified by section '4.2.1. Key expansion' and - * return a hs_ntor_rend_circuit_keys_t structure with the computed keys. */ -hs_ntor_rend_circuit_keys_t * -hs_ntor_circuit_key_expansion( - const hs_ntor_rend_cell_keys_t *hs_ntor_rend_cell_keys) + +/** Given the rendezvous key seed in <b>ntor_key_seed</b> (of size + * DIGEST256_LEN), do the circuit key expansion as specified by section + * '4.2.1. Key expansion' and place the keys in <b>keys_out</b> (which must be + * of size HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN). */ +void +hs_ntor_circuit_key_expansion(const uint8_t *ntor_key_seed, uint8_t *keys_out) { uint8_t *ptr; uint8_t kdf_input[NTOR_KEY_EXPANSION_KDF_INPUT_LEN]; - uint8_t keys[NTOR_KEY_EXPANSION_KDF_OUTPUT_LEN]; crypto_xof_t *xof; - hs_ntor_rend_circuit_keys_t *rend_circuit_keys = NULL;
/* Let's build the input to the KDF */ ptr = kdf_input; - APPEND(ptr, hs_ntor_rend_cell_keys->ntor_key_seed, DIGEST256_LEN); + APPEND(ptr, ntor_key_seed, DIGEST256_LEN); APPEND(ptr, M_HSEXPAND, strlen(M_HSEXPAND)); tor_assert(ptr == kdf_input + sizeof(kdf_input));
/* Generate the keys */ xof = crypto_xof_new(); crypto_xof_add_bytes(xof, kdf_input, sizeof(kdf_input)); - crypto_xof_squeeze_bytes(xof, keys, sizeof(keys)); + crypto_xof_squeeze_bytes(xof, keys_out, HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN); crypto_xof_free(xof); - - /* Generate keys structure and assign keys to it */ - rend_circuit_keys = tor_malloc_zero(sizeof(hs_ntor_rend_circuit_keys_t)); - ptr = keys; - memcpy(rend_circuit_keys->KH, ptr, DIGEST256_LEN); - ptr += DIGEST256_LEN;; - memcpy(rend_circuit_keys->Df, ptr, DIGEST256_LEN); - ptr += DIGEST256_LEN; - memcpy(rend_circuit_keys->Db, ptr, DIGEST256_LEN); - ptr += DIGEST256_LEN; - memcpy(rend_circuit_keys->Kf, ptr, CIPHER256_KEY_LEN); - ptr += CIPHER256_KEY_LEN; - memcpy(rend_circuit_keys->Kb, ptr, CIPHER256_KEY_LEN); - ptr += CIPHER256_KEY_LEN; - tor_assert(ptr == keys + sizeof(keys)); - - return rend_circuit_keys; }
diff --git a/src/or/hs_ntor.h b/src/or/hs_ntor.h index cd75f46..3a97e17 100644 --- a/src/or/hs_ntor.h +++ b/src/or/hs_ntor.h @@ -6,6 +6,10 @@
#include "or.h"
+/* Output length of KDF for key expansion */ +#define HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN \ + (DIGEST256_LEN*2 + CIPHER256_KEY_LEN*2) + /* Key material needed to encode/decode INTRODUCE1 cells */ typedef struct { /* Key used for encryption of encrypted INTRODUCE1 blob */ @@ -23,21 +27,6 @@ typedef struct { uint8_t ntor_key_seed[DIGEST256_LEN]; } hs_ntor_rend_cell_keys_t;
-/* Key material resulting from key expansion as detailed in section "4.2.1. Key - * expansion" of rend-spec-ng.txt. */ -typedef struct { - /* Per-circuit key material used in ESTABLISH_INTRO cell */ - uint8_t KH[DIGEST256_LEN]; - /* Authentication key for outgoing RELAY cells */ - uint8_t Df[DIGEST256_LEN]; - /* Authentication key for incoming RELAY cells */ - uint8_t Db[DIGEST256_LEN]; - /* Encryption key for outgoing RELAY cells */ - uint8_t Kf[CIPHER256_KEY_LEN]; - /* Decryption key for incoming RELAY cells */ - uint8_t Kb[CIPHER256_KEY_LEN]; -} hs_ntor_rend_circuit_keys_t; - int hs_ntor_client_get_introduce1_keys( const ed25519_public_key_t *intro_auth_pubkey, const curve25519_public_key_t *intro_enc_pubkey, @@ -66,8 +55,8 @@ int hs_ntor_service_get_rendezvous1_keys( const curve25519_public_key_t *client_ephemeral_enc_pubkey, hs_ntor_rend_cell_keys_t *hs_ntor_rend_cell_keys_out);
-hs_ntor_rend_circuit_keys_t *hs_ntor_circuit_key_expansion( - const hs_ntor_rend_cell_keys_t *hs_ntor_rend_cell_keys); +void hs_ntor_circuit_key_expansion(const uint8_t *ntor_key_seed, + uint8_t *keys_out);
int hs_ntor_client_rendezvous2_mac_is_good( const hs_ntor_rend_cell_keys_t *hs_ntor_rend_cell_keys,