hs_indexes.py (2910B)
1 # 2 # The hidden service subsystem has two type of index. The first type is a 3 # value that each node in the network gets assigned to using their identity 4 # key which is their position in the hashring. (hs_build_hsdir_index()). 5 # 6 # The second type is a value that both the client and service computes to 7 # store/fetch the descriptor on the hashring. (hs_build_hs_index()). 8 # 9 10 # Future imports for Python 2.7, mandatory in 3.0 11 from __future__ import division 12 from __future__ import print_function 13 from __future__ import unicode_literals 14 15 import sys 16 import hashlib 17 import struct 18 import base64 19 20 # Python 3.6+, the SHA3 is available in hashlib natively. Else this requires 21 # the pysha3 package (pip install pysha3). 22 if sys.version_info < (3, 6): 23 import sha3 24 # Test vector to make sure the right sha3 version will be used. pysha3 < 1.0 25 # used the old Keccak implementation. During the finalization of SHA3, NIST 26 # changed the delimiter suffix from 0x01 to 0x06. The Keccak sponge function 27 # stayed the same. pysha3 1.0 provides the previous Keccak hash, too. 28 TEST_VALUE = "e167f68d6563d75bb25f3aa49c29ef612d41352dc00606de7cbd630bb2665f51" 29 if TEST_VALUE != sha3.sha3_256(b"Hello World").hexdigest(): 30 print("pysha3 version is < 1.0. Please install from:") 31 print("https://github.com/tiran/pysha3https://github.com/tiran/pysha3") 32 sys.exit(1) 33 34 # The first index we'll build is the position index in the hashring that is 35 # constructed by the hs_build_hsdir_index() function. Construction is: 36 # SHA3-256("node-idx" | node_identity | 37 # shared_random_value | INT_8(period_length) | INT_8(period_num) ) 38 39 PREFIX = "node-idx".encode() 40 # 32 bytes ed25519 pubkey. 41 IDENTITY = ("\x42" * 32).encode() 42 # SRV is 32 bytes. 43 SRV = ("\x43" * 32).encode() 44 # Time period length is a 8 bytes value. 45 PERIOD_LEN = 1440 46 # Period number is a 8 bytes value. 47 PERIOD_NUM = 42 48 49 data = struct.pack('!8s32s32sQQ', PREFIX, IDENTITY, SRV, PERIOD_NUM, 50 PERIOD_LEN) 51 hsdir_index = hashlib.sha3_256(data).hexdigest() 52 53 print("[hs_build_hsdir_index] %s" % (hsdir_index)) 54 55 # The second index we'll build is where the HS stores and the client fetches 56 # the descriptor on the hashring. It is constructed by the hs_build_hs_index() 57 # function and the construction is: 58 # SHA3-256("store-at-idx" | blinded_public_key | 59 # INT_8(replicanum) | INT_8(period_num) | INT_8(period_length) ) 60 61 PREFIX = "store-at-idx".encode() 62 # 32 bytes ed25519 pubkey. 63 PUBKEY = ("\x42" * 32).encode() 64 # Replica number is a 8 bytes value. 65 REPLICA_NUM = 1 66 # Time period length is a 8 bytes value. 67 PERIOD_LEN = 1440 68 # Period number is a 8 bytes value. 69 PERIOD_NUM = 42 70 71 data = struct.pack('!12s32sQQQ', PREFIX, PUBKEY, REPLICA_NUM, PERIOD_LEN, 72 PERIOD_NUM) 73 hs_index = hashlib.sha3_256(data).hexdigest() 74 75 print("[hs_build_hs_index] %s" % (hs_index))