def read_cut_verifier_challenges(sbb_dict, sbb, db):
""" Read verifier challenges from proof:cutandchoose_verifier_challenges; save into db.
"""
chs = sbb_dict['proof:cutandchoose_verifier_challenges']['challenges']
assert isdict(chs, ['cut'])
assert isdict(chs['cut'], ['icl', 'opl'])
icl = chs['cut']['icl']
assert isinstance(icl, list)
assert len(icl) == db['n_reps'] // 2
assert set(icl).issubset(db['k_list'])
opl = chs['cut']['opl']
assert isinstance(opl, list)
assert len(opl) == db['n_reps'] // 2
assert set(opl).issubset(db['k_list'])
assert set(icl).isdisjoint(set(opl))
db['icl'] = icl
db['opl'] = opl
# now check that icl and opl are consistent with sbb_hash
# see make_cut_verifier_challenges in sv_prover.py
rand_name = 'cut_verifier_challenges'
sbb_hash = sbb_dict['proof:cutandchoose_verifier_challenges']['sbb_hash']
stop_before_header = 'proof:cutandchoose_verifier_challenges'
sbb_hash2 = sv.bytes2hex(hash_sbb(sbb, stop_before_header))
assert sbb_hash2 == sbb_hash, "sbb_hash2: " + str(
sbb_hash2) + "sbb_hash: " + str(sbb_hash)
sv.init_randomness_source(rand_name, sv.hex2bytes(sbb_hash))
pi = sv.random_permutation(db['n_reps'], rand_name)
m = db['n_reps'] // 2
pi = [pi[i] for i in range(2 * m)]
icl2 = [db['k_list'][i] for i in sorted(pi[:m])]
opl2 = [db['k_list'][i] for i in sorted(pi[m:])]
assert icl2 == icl
assert opl2 == opl
print('read_cut_verifier_challenges: successful.')
def mix_phase_generate_permutations(self, row_index, col_index):
assert row_index == 'a'
election = self.election
# generate permutations (and inverses) used in each column
# in practice, these could be generated by row 0 server
# and sent securely to the others in the same column.
for race_id in election.race_ids:
j = col_index
rand_name = self.sdb[race_id]['a'][j]['rand_name']
sv.init_randomness_source(rand_name) # optional - TODO remove after transition to unshared memory only
for k in election.k_list:
pi = sv.random_permutation(election.p_list, rand_name)
pi_inv = sv.inverse_permutation(pi)
for i in self.row_list:
self.sdb[race_id][i][j][k]['pi'] = pi
self.sdb[race_id][i][j][k]['pi_inv'] = pi_inv
dict_update_to_share = dict()
for race_id in election.race_ids:
dict_update_to_share[race_id] = dict()
for i in self.row_list:
dict_update_to_share[race_id][i] = dict()
j = col_index
assert type(j)==int
dict_update_to_share[race_id][i][j] = dict()
for k in election.k_list:
dict_update_to_share[race_id][i][j][k] = dict()
dict_update_to_share[race_id][i][j][k]['pi'] = self.sdb[race_id][i][j][k]['pi']
dict_update_to_share[race_id][i][j][k]['pi_inv'] = self.sdb[race_id][i][j][k]['pi_inv']
return dict_update_to_share
def read_leftright_verifier_challenges(sbb_dict, sbb, db):
""" Read verifier challenges from proof:leftright_verifier_challenges; save into db.
"""
chs = sbb_dict['proof:leftright_verifier_challenges']['challenges']
assert isdict(chs, ['leftright'])
leftright = chs['leftright']
assert isdict(leftright, db['race_ids'])
for race_id in leftright.keys():
lr_dict = leftright[race_id]
assert set(lr_dict.keys()) == set(db['p_list'])
for p in db['p_list']:
lr = lr_dict[p]
assert lr == 'left' or lr == 'right'
db['leftright'] = leftright
# now check that icl, opl, and leftright are consistent with sbb_hash
# see make_verifier_challenges in sv_prover.py
rand_name = 'leftright_verifier_challenges'
sbb_hash = sbb_dict['proof:leftright_verifier_challenges']['sbb_hash']
stop_before_header = 'proof:leftright_verifier_challenges'
sbb_hash2 = sv.bytes2hex(hash_sbb(sbb, stop_before_header))
assert sbb_hash2 == sbb_hash, "sbb_hash2: " + str(
sbb_hash2) + "sbb_hash: " + str(sbb_hash)
sv.init_randomness_source(rand_name, sv.hex2bytes(sbb_hash))
leftright2 = make_left_right_challenges(rand_name, db)
assert leftright2 == leftright
print('read_leftright_verifier_challenges: successful.')
def __init__(self, election, voter_id, px):
""" Initialize voter object for this election.
Here voter_id is a string identifying the voter, and
px is a "position identifier": 'p0', 'p1', ...
"""
self.election = election
assert isinstance(voter_id, str)
self.voter_id = voter_id
self.px = px
# randomness source per voter
self.rand_name = "voter:"+voter_id
sv.init_randomness_source(self.rand_name)
self.receipts = dict() # maps ballot_id to hash value of receipt
def make_cut_verifier_challenges(election, sbb_hash):
""" Return a dict containing "verifier challenges" for this proof.
This is based on randomness (hash of sbb, fiat-shamir style),
but could also incorporate additional random input (e.g.
dice rolls).
"""
election.sbb_hash = sbb_hash
rand_name = "cut_verifier_challenges"
sv.init_randomness_source(rand_name, sbb_hash)
challenges = dict()
make_cut_and_choose_challenges(election, rand_name, challenges)
sv.update_nested_dict(election.server.challenges, challenges)
proof = ("proof:cutandchoose_verifier_challenges", {
"sbb_hash": sv.bytes2hex(sbb_hash),
"challenges": challenges
})
return proof
def __init__(self, election, voter_id, px):
""" Initialize voter object for this election.
Here voter_id is a string identifying the voter, and
px is a "position identifier": 'p0', 'p1', ...
"""
self.election = election
assert isinstance(voter_id, str)
self.voter_id = voter_id
self.px = px
# randomness source per voter
self.rand_name = "voter:" + voter_id
sv.init_randomness_source(self.rand_name)
self.receipts = dict() # maps ballot_id to hash value of receipt
def read_verifier_challenges(sbb_dict, sbb, db):
""" Read verifier challenges from proof:verifier_challenges; save into db.
"""
chs = sbb_dict['proof:verifier_challenges']['challenges']
assert isdict(chs, ['cut', 'leftright'])
assert isdict(chs['cut'], ['icl', 'opl'])
icl = chs['cut']['icl']
assert isinstance(icl, list)
assert len(icl) == db['n_reps'] // 2
assert set(icl).issubset(db['k_list'])
opl = chs['cut']['opl']
assert isinstance(opl, list)
assert len(opl) == db['n_reps'] // 2
assert set(opl).issubset(db['k_list'])
assert set(icl).isdisjoint(set(opl))
db['icl'] = icl
db['opl'] = opl
leftright = chs['leftright']
assert isdict(leftright, db['race_ids'])
for race_id in leftright.keys():
lr_dict = leftright[race_id]
assert set(lr_dict.keys()) == set(db['p_list'])
for p in db['p_list']:
lr = lr_dict[p]
assert lr == 'left' or lr == 'right'
db['leftright'] = leftright
# now check that icl, opl, and leftright are consistent with sbb_hash
# see make_verifier_challenges in sv_prover.py
rand_name = 'verifier_challenges'
sbb_hash = sbb_dict['proof:verifier_challenges']['sbb_hash']
stop_before_header = 'proof:verifier_challenges'
sbb_hash2 = sv.bytes2hex(hash_sbb(sbb, stop_before_header))
assert sbb_hash2 == sbb_hash
sv.init_randomness_source(rand_name, sv.hex2bytes(sbb_hash))
pi = sv.random_permutation(db['n_reps'], rand_name)
m = db['n_reps'] // 2
pi = [pi[i] for i in range(2 * m)]
icl2 = [db['k_list'][i] for i in sorted(pi[:m])]
opl2 = [db['k_list'][i] for i in sorted(pi[m:])]
assert icl2 == icl
assert opl2 == opl
leftright2 = make_left_right_challenges(rand_name, db)
assert leftright2 == leftright
print('read_verifier_challenges: successful.')
def read_verifier_challenges(sbb_dict, sbb, db):
""" Read verifier challenges from proof:verifier_challenges; save into db.
"""
chs = sbb_dict['proof:verifier_challenges']['challenges']
assert isdict(chs, ['cut', 'leftright'])
assert isdict(chs['cut'], ['icl', 'opl'])
icl = chs['cut']['icl']
assert isinstance(icl, list)
assert len(icl) == db['n_reps'] // 2
assert set(icl).issubset(db['k_list'])
opl = chs['cut']['opl']
assert isinstance(opl, list)
assert len(opl) == db['n_reps'] // 2
assert set(opl).issubset(db['k_list'])
assert set(icl).isdisjoint(set(opl))
db['icl'] = icl
db['opl'] = opl
leftright = chs['leftright']
assert isdict(leftright, db['race_ids'])
for race_id in leftright.keys():
lr_dict = leftright[race_id]
assert set(lr_dict.keys()) == set(db['p_list'])
for p in db['p_list']:
lr = lr_dict[p]
assert lr == 'left' or lr == 'right'
db['leftright'] = leftright
# now check that icl, opl, and leftright are consistent with sbb_hash
# see make_verifier_challenges in sv_prover.py
rand_name = 'verifier_challenges'
sbb_hash = sbb_dict['proof:verifier_challenges']['sbb_hash']
stop_before_header = 'proof:verifier_challenges'
sbb_hash2 = sv.bytes2hex(hash_sbb(sbb, stop_before_header))
assert sbb_hash2 == sbb_hash
sv.init_randomness_source(rand_name, sv.hex2bytes(sbb_hash))
pi = sv.random_permutation(db['n_reps'], rand_name)
m = db['n_reps'] // 2
pi = [pi[i] for i in range(2*m)]
icl2 = [db['k_list'][i] for i in sorted(pi[:m])]
opl2 = [db['k_list'][i] for i in sorted(pi[m:])]
assert icl2 == icl
assert opl2 == opl
leftright2 = make_left_right_challenges(rand_name, db)
assert leftright2 == leftright
print('read_verifier_challenges: successful.')
def make_verifier_challenges(election):
""" Return a dict containing "verifier challenges" for this proof.
This is based on randomness (hash of sbb, fiat-shamir style),
but could also incorporate additional random input (e.g.
dice rolls).
"""
sbb_hash = election.sbb.hash_sbb(public=True)
election.sbb_hash = sbb_hash
rand_name = "verifier_challenges"
sv.init_randomness_source(rand_name, sbb_hash)
challenges = dict()
make_cut_and_choose_challenges(election, rand_name, challenges)
make_left_right_challenges(election, rand_name, challenges)
election.sbb.post("proof:verifier_challenges",
{"sbb_hash": sv.bytes2hex(sbb_hash),
"challenges": challenges},
time_stamp=False)
return challenges
def __init__(self, election, race_id, choices):
""" Initialize race
race_id is a string
choices is list consisting of
one string for each allowable candidate/choice name
a string "************************" of stars
of the maximum allowable length of a write-in
if write-ins are allowed.
Example:
race_id = "President"
choices = ("Smith", "Jones", "********")
defines a race (for President), and
for this race the voter may vote for Smith, for Jones, or
may cast a write-in vote of length at most 8 characters.
"""
assert isinstance(race_id, str) and len(race_id) > 0
assert isinstance(choices, (list, tuple)) and len(choices) > 0
# must be more than one choice, except if sole choice is for write-ins
assert len(choices) > 1 or choices[0] in "*"*1000
# choices must be distinct
assert len(choices) == len(set(choices))
# choices must be strings
assert all([isinstance(choice, str) for choice in choices])
self.election = election
self.race_id = race_id
self.choices = choices
# set race.race_modulus = modulus for representing choices in this race.
# note that for computation and comparison purposes, choices will
# be converted to type bytes
# make race_modulus a prime big enough to encode all possible choices
self.max_choice_len = max([len(choice.encode()) for choice in choices])
self.race_modulus = sv.make_prime(256**self.max_choice_len)
self.tally = None
rand_name = "random:"+race_id # only for simulation
self.rand_name = rand_name
sv.init_randomness_source(rand_name)
def make_verifier_challenges(election):
""" Return a dict containing "verifier challenges" for this proof.
This is based on randomness (hash of sbb, fiat-shamir style),
but could also incorporate additional random input (e.g.
dice rolls).
"""
sbb_hash = election.sbb.hash_sbb(public=True)
election.sbb_hash = sbb_hash
rand_name = "verifier_challenges"
sv.init_randomness_source(rand_name, sbb_hash)
challenges = dict()
make_cut_and_choose_challenges(election, rand_name, challenges)
make_left_right_challenges(election, rand_name, challenges)
election.sbb.post("proof:verifier_challenges", {
"sbb_hash": sv.bytes2hex(sbb_hash),
"challenges": challenges
},
time_stamp=False)
return challenges
def __init__(self, election, n_fail, n_leak):
""" Initialize server. This is one for the whole election.
The server array has the given number of rows and columns
as parts or sub-servers. Here we simulate the actions of
these sub-servers.
n_fail = number of servers that could fail
n_leak = number of servers that my leak information
"""
assert isinstance(n_fail, int) and n_fail >= 0
assert isinstance(n_leak, int) and n_leak >= 0
self.election = election
self.n_fail = n_fail
self.n_leak = n_leak
if self.n_fail > 0:
self.cols = 1 + n_leak
self.rows = 2 + n_fail + n_leak
self.threshold = 2 + n_leak # number of rows needed to reconstruct
else:
self.cols = 1 + n_leak
self.rows = 1 + n_leak
self.threshold = 1 + n_leak
rows = self.rows
cols = self.cols
threshold = self.threshold
# each row has an identifier in "abcd..."
assert rows <= 26
self.row_list = sv.row_list(rows)
self.challenges = dict()
# The state of the server in row i, col j is represented
# here in the dictionary P[race_id][i][j] for the given race
# where i in row_list and 0 <= j < cols.
# create one top-level dict sdb as database for this main server
self.sdb = dict()
# within the top level dict sdb, create a three-dimensional array of
# sub-dicts for data storage, each addressed as sdb[race_id][i][j]
for race in election.races:
race_id = race.race_id
self.sdb[race_id] = dict()
for i in self.row_list:
self.sdb[race_id][i] = dict()
for j in range(cols):
self.sdb[race_id][i][j] = dict()
# each server has its own random-number source for each race
# in practice, these could be derived from true random seeds input
# independently to each server
for race_id in election.race_ids:
for i in self.row_list:
for j in range(cols):
rand_name = "server:" + race_id + ":" + \
str(i) + ":" + str(j)
self.sdb[race_id][i][j]['rand_name'] = rand_name
sv.init_randomness_source(rand_name)
# within each sub-dict sdb[race_id][i][j] create a variety of lists for
# storage of cast votes and associated data, including 2m-way replicated
# lists needed for the 2m mixes (passes) needed.
for race_id in election.race_ids:
for i in self.row_list:
# first-column lists for storing cast votes and secrets
sdbp = self.sdb[race_id][i][0]
sdbp['ballot_id'] = dict() # ballot_id (indices from p_list)
sdbp['cu'] = dict() # commitments to u
sdbp['cv'] = dict() # commitments to v
sdbp['x'] = dict() # choice x, where x = u+v mod M
sdbp['u'] = dict() # u
sdbp['v'] = dict() # v
sdbp['ru'] = dict() # randomness to open com(u)
sdbp['rv'] = dict() # randomness to open com(v)
# for all columns, have 2m-way replicated data structures
for j in range(cols):
sdbp = self.sdb[race_id][i][j]
for k in election.k_list:
sdbp[k] = dict()
sdbp[k]['x'] = dict() # inputs on pass k
sdbp[k]['y'] = dict() # outputs on pass k
# last-column lists for storing published lists of commitments
for k in election.k_list:
sdbp = self.sdb[race_id][i][self.cols-1][k]
sdbp['y'] = dict()
sdbp['u'] = dict()
sdbp['v'] = dict()
sdbp['ru'] = dict()
sdbp['rv'] = dict()
sdbp['cu'] = dict()
sdbp['cv'] = dict()
# create one top-level dict sdb as database for this main server (a unshared copy of sbd)
self.sdb = deepcopy(self.sdb) # TODO remove
def __init__(self, election, n_fail, n_leak):
""" Initialize server. This is one for the whole election.
The server array has the given number of rows and columns
as parts or sub-servers. Here we simulate the actions of
these sub-servers.
n_fail = number of servers that could fail
n_leak = number of servers that my leak information
"""
assert isinstance(n_fail, int) and n_fail >= 0
assert isinstance(n_leak, int) and n_leak >= 0
self.election = election
self.n_fail = n_fail
self.n_leak = n_leak
if self.n_fail > 0:
self.cols = 1 + n_leak
self.rows = 2 + n_fail + n_leak
self.threshold = 2 + n_leak # number of rows needed to reconstruct
else:
self.cols = 1 + n_leak
self.rows = 1 + n_leak
self.threshold = 1 + n_leak
rows = self.rows
cols = self.cols
threshold = self.threshold
# each row has an identifier in "abcd..."
assert rows <= 26
self.row_list = sv.row_list(rows)
# The state of the server in row i, col j is represented
# here in the dictionary P[race_id][i][j] for the given race
# where i in row_list and 0 <= j < cols.
# create one top-level dict sdb as database for this main server
self.sdb = dict()
# within the top level dict sdb, create a three-dimensional array of
# sub-dicts for data storage, each addressed as sdb[race_id][i][j]
for race in election.races:
race_id = race.race_id
self.sdb[race_id] = dict()
for i in self.row_list:
self.sdb[race_id][i] = dict()
for j in range(cols):
self.sdb[race_id][i][j] = dict()
# each server has its own random-number source for each race
# in practice, these could be derived from true random seeds input
# independently to each server
for race_id in election.race_ids:
for i in self.row_list:
for j in range(cols):
rand_name = "server:" + race_id + ":" + \
str(i) + ":" + str(j)
self.sdb[race_id][i][j]['rand_name'] = rand_name
sv.init_randomness_source(rand_name)
# within each sub-dict sdb[race_id][i][j] create a variety of lists for
# storage of cast votes and associated data, including 2m-way replicated
# lists needed for the 2m mixes (passes) needed.
for race_id in election.race_ids:
for i in self.row_list:
# first-column lists for storing cast votes and secrets
sdbp = self.sdb[race_id][i][0]
sdbp['ballot_id'] = dict() # ballot_id (indices from p_list)
sdbp['cu'] = dict() # commitments to u
sdbp['cv'] = dict() # commitments to v
sdbp['x'] = dict() # choice x, where x = u+v mod M
sdbp['u'] = dict() # u
sdbp['v'] = dict() # v
sdbp['ru'] = dict() # randomness to open com(u)
sdbp['rv'] = dict() # randomness to open com(v)
# for all columns, have 2m-way replicated data structures
for j in range(cols):
sdbp = self.sdb[race_id][i][j]
for k in election.k_list:
sdbp[k] = dict()
sdbp[k]['x'] = dict() # inputs on pass k
sdbp[k]['y'] = dict() # outputs on pass k
# last-column lists for storing published lists of commitments
for k in election.k_list:
sdbp = self.sdb[race_id][i][self.cols-1][k]
sdbp['y'] = dict()
sdbp['u'] = dict()
sdbp['v'] = dict()
sdbp['ru'] = dict()
sdbp['rv'] = dict()
sdbp['cu'] = dict()
sdbp['cv'] = dict()
# post on log that server array is set up
election.sbb.post("setup:server-array",
{"rows": rows, "cols": cols,
"n_reps": election.n_reps,
"threshold": threshold,
'json_indent': election.json_indent},
time_stamp=False)
def compute_output_commitments(election, row_index, col_index):
""" Make commitments to all output values and save them in sdbp.
For each race,
for each of n_reps copies (indexed by k),
for each row (indexed by i)
for each of the n vote shares (call them y)
compute two commitments (cu and cv) to split-value rep (u,v) of y.
using randomization values ru and rv.
"""
cols = election.server.cols
full_output = dict()
for race in election.races:
race_modulus = race.race_modulus
race_id = race.race_id
full_output[race_id] = dict()
for k in election.k_list:
full_output[race_id][k] = dict()
for py in election.p_list:
full_output[race_id][k][py] = dict()
if col_index == cols - 1: # TODO move this logic to ServerMix handler
i = row_index
rand_name = \
election.server.sdb[race_id][i][cols-1]['rand_name']
sv.init_randomness_source(
rand_name) # TODO optional remove later
sdbp = election.server.sdb[race_id][i][cols - 1][k]
y = sdbp['y'][py]
(u, v) = sv.get_sv_pair(y, rand_name, race_modulus)
ru = sv.bytes2base64(sv.get_random_from_source(rand_name))
rv = sv.bytes2base64(sv.get_random_from_source(rand_name))
cu = sv.com(u, ru)
cv = sv.com(v, rv)
sdbp['u'][py] = u
sdbp['v'][py] = v
sdbp['ru'][py] = ru
sdbp['rv'][py] = rv
sdbp['cu'][py] = cu
sdbp['cv'][py] = cv
ballot = {
'y': y,
'u': u,
'v': v,
'ru': ru,
'rv': rv,
'cu': cu,
'cv': cv
}
full_output[race_id][k][py][i] = ballot
election.full_output = full_output
coms = dict()
# same as full_output, but only giving non-secret values (i.e. cu, cv)
for race in election.races:
race_id = race.race_id
coms[race_id] = dict()
for k in election.k_list:
coms[race_id][k] = dict()
for py in election.p_list:
coms[race_id][k][py] = dict()
'''for i in election.server.row_list: # TODO remove this for loop -> shared memory
coms[race_id][k][py][i] = \
{'cu': full_output[race_id][k][py][i]['cu'],
'cv': full_output[race_id][k][py][i]['cv']}'''
coms[race_id][k][py] = dict()
if col_index == cols - 1: # TODO move this logic to ServerMix handler
i = row_index
coms[race_id][k][py][i] = \
{'cu': full_output[race_id][k][py][i]['cu'],
'cv': full_output[race_id][k][py][i]['cv']}
election.output_commitments = coms
return ("proof:output_commitments", {"commitments": coms})
