test: Unit test for the hs indexes

Using a test vector in python, test both hs_build_hsdir_index() and
hs_build_hs_index().

This commit also adds the hs_build_address.py to EXTRA_DIST which was missing.

Signed-off-by: David Goulet <dgoulet@torproject.org>

src/test/hs_indexes.py

@@ -0,0 +1,70 @@
+#
+# The hidden service subsystem has two type of index. The first type is a
+# value that each node in the network gets assigned to using their identity
+# key which is their position in the hashring. (hs_build_hsdir_index()).
+#
+# The second type is a value that both the client and service computes to
+# store/fetch the descriptor on the hashring. (hs_build_hs_index()).
+#
+
+import sys
+import hashlib
+import struct
+import base64
+
+# Python 3.6+, the SHA3 is available in hashlib natively. Else this requires
+# the pysha3 package (pip install pysha3).
+if sys.version_info < (3, 6):
+    import sha3
+    # Test vector to make sure the right sha3 version will be used. pysha3 < 1.0
+    # used the old Keccak implementation. During the finalization of SHA3, NIST
+    # changed the delimiter suffix from 0x01 to 0x06. The Keccak sponge function
+    # stayed the same. pysha3 1.0 provides the previous Keccak hash, too.
+    TEST_VALUE = "e167f68d6563d75bb25f3aa49c29ef612d41352dc00606de7cbd630bb2665f51"
+    if TEST_VALUE != sha3.sha3_256(b"Hello World").hexdigest():
+        print("pysha3 version is < 1.0. Please install from:")
+        print("https://github.com/tiran/pysha3https://github.com/tiran/pysha3")
+        sys.exit(1)
+
+# The first index we'll build is the position index in the hashring that is
+# constructed by the hs_build_hsdir_index() function. Construction is:
+#   SHA3-256("node-idx" | node_identity |
+#            shared_random_value | INT_8(period_length) | INT_8(period_num) )
+
+PREFIX = "node-idx".encode()
+# 32 bytes ed25519 pubkey.
+IDENTITY = ("\x42" * 32).encode()
+# SRV is 32 bytes.
+SRV = ("\x43" * 32).encode()
+# Time period length is a 8 bytes value.
+PERIOD_LEN = 1440
+# Period number is a 8 bytes value.
+PERIOD_NUM = 42
+
+data = struct.pack('!8s32s32sQQ', PREFIX, IDENTITY, SRV, PERIOD_NUM,
+                                  PERIOD_LEN)
+hsdir_index = hashlib.sha3_256(data).hexdigest()
+
+print("[hs_build_hsdir_index] %s" % (hsdir_index))
+
+# The second index we'll build is where the HS stores and the client fetches
+# the descriptor on the hashring. It is constructed by the hs_build_hs_index()
+# function and the construction is:
+#   SHA3-256("store-at-idx" | blinded_public_key |
+#            INT_8(replicanum) | INT_8(period_num) | INT_8(period_length) )
+
+PREFIX = "store-at-idx".encode()
+# 32 bytes ed25519 pubkey.
+PUBKEY = ("\x42" * 32).encode()
+# Replica number is a 8 bytes value.
+REPLICA_NUM = 1
+# Time period length is a 8 bytes value.
+PERIOD_LEN = 1440
+# Period number is a 8 bytes value.
+PERIOD_NUM = 42
+
+data = struct.pack('!12s32sQQQ', PREFIX, PUBKEY, REPLICA_NUM, PERIOD_LEN,
+                                   PERIOD_NUM)
+hs_index = hashlib.sha3_256(data).hexdigest()
+
+print("[hs_build_hs_index]   %s" % (hs_index))

src/test/include.am

@@ -332,6 +332,8 @@ EXTRA_DIST += \
 	src/test/bt_test.py \
 	src/test/ntor_ref.py \
 	src/test/hs_ntor_ref.py \
+	src/test/hs_build_address.py \
+	src/test/hs_indexes.py \
 	src/test/fuzz_static_testcases.sh \
 	src/test/slownacl_curve25519.py \
 	src/test/zero_length_keys.sh \

src/test/test_hs_common.c

@@ -1453,6 +1453,51 @@ helper_client_pick_hsdir(const ed25519_public_key_t *onion_identity_pk,
   ;
 }
 
+static void
+test_hs_indexes(void *arg)
+{
+  int ret;
+  uint64_t period_num = 42;
+  ed25519_public_key_t pubkey;
+
+  (void) arg;
+
+  /* Build the hs_index */
+  {
+    uint8_t hs_index[DIGEST256_LEN];
+    const char *b32_test_vector =
+      "37e5cbbd56a22823714f18f1623ece5983a0d64c78495a8cfab854245e5f9a8a";
+    char test_vector[DIGEST256_LEN];
+    ret = base16_decode(test_vector, sizeof(test_vector), b32_test_vector,
+                        strlen(b32_test_vector));
+    tt_int_op(ret, OP_EQ, sizeof(test_vector));
+    /* Our test vector uses a public key set to 32 bytes of \x42. */
+    memset(&pubkey, '\x42', sizeof(pubkey));
+    hs_build_hs_index(1, &pubkey, period_num, hs_index);
+    tt_mem_op(hs_index, OP_EQ, test_vector, sizeof(hs_index));
+  }
+
+  /* Build the hsdir_index */
+  {
+    uint8_t srv[DIGEST256_LEN];
+    uint8_t hsdir_index[DIGEST256_LEN];
+    const char *b32_test_vector =
+      "db475361014a09965e7e5e4d4a25b8f8d4b8f16cb1d8a7e95eed50249cc1a2d5";
+    char test_vector[DIGEST256_LEN];
+    ret = base16_decode(test_vector, sizeof(test_vector), b32_test_vector,
+                        strlen(b32_test_vector));
+    tt_int_op(ret, OP_EQ, sizeof(test_vector));
+    /* Our test vector uses a public key set to 32 bytes of \x42. */
+    memset(&pubkey, '\x42', sizeof(pubkey));
+    memset(srv, '\x43', sizeof(srv));
+    hs_build_hsdir_index(&pubkey, srv, period_num, hsdir_index);
+    tt_mem_op(hsdir_index, OP_EQ, test_vector, sizeof(hsdir_index));
+  }
+
+ done:
+  ;
+}
+
 #define EARLY_IN_SRV_TO_TP 0
 #define LATE_IN_SRV_TO_TP 1
 #define EARLY_IN_TP_TO_SRV 2
@@ -1751,6 +1796,9 @@ struct testcase_t hs_common_tests[] = {
     NULL, NULL },
   { "client_service_hsdir_set_sync", test_client_service_hsdir_set_sync,
     TT_FORK, NULL, NULL },
+  { "hs_indexes", test_hs_indexes, TT_FORK,
+    NULL, NULL },
+
   END_OF_TESTCASES
 };