def share_secret(num_players, reconstruction_threshold, max_secret_length, secret):
'''
Args:
num_players, the number of shares to be distributed
reconstruction_threshold, the number of shares needed for reconstruction
any collection of fewer shares will reveal no information about the secret
max_secret_length, the maximum length of the secret represented as a bytestring (ie, len(secret))
secret, a bytestring to be Shamir secret shared
Returns:
a list of strings, each representing an integer, that can be passed to reconstruct_secret
Raises:
ValueError, the input arguments fail validation
'''
secret_int = serialization.convert_bytestring_to_int(secret)
points = _share_secret_int(num_players, reconstruction_threshold, max_secret_length + 1, secret_int)
return [str(pairing.elegant_pair(*tup)) for tup in points]
def share_authenticated_secret(players, reconstruction_threshold, max_secret_length, secret):
'''
Args:
players, a list of unique string ids for all players
reconstruction_threshold, the number of shares needed for reconstruction
any collection of fewer shares will reveal no information about the secret
max_secret_length, the maximum length of the secret represented as a bytestring (ie, len(secret))
secret, a bytestring to be Shamir secret shared
Returns:
a dictionary of ids (from the players argument) to robust secret shares, which consist of
a share
a map of player ids to keys for the shares held by those players
a map of player ids to vectors for this share
that can be verified by keys held by those players
Raises:
ValueError, the input parameters fail validation (see share_secret of schemes/sss.py)
'''
num_players = len(players)
secret_int = serialization.convert_bytestring_to_int(secret)
# generate shares of the secret s: ((x_1, s_1), . . . , (x_n, s_n))
int_shares = [pairing.elegant_pair(*share) for share in
sss._share_secret_int(num_players,
reconstruction_threshold,
max_secret_length + 1, # conversion to an integer adds one byte
secret_int)]
# assign shares to players
shares_map = {player: share for (player, share) in zip(players, int_shares)}
batch_keys, batch_vectors = defaultdict(dict), defaultdict(dict)
for player in players: # generate n MAC keys k_ij and vectors t_ij = MAC(k_ij, s_j) per share s_j
keys, vectors = authentication.generate_batch(num_players, shares_map[player], max_secret_length + 1)
for player_id, key, vector in zip(players, keys, vectors):
batch_keys[player][player_id] = key
batch_vectors[player][player_id] = vector
return _make_robust_shares(shares_map, batch_keys, batch_vectors)
def run_pair_unpair(tup):
z = pairing.elegant_pair(tup[0], tup[1])
result = pairing.elegant_unpair(z)
return tup == result
