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_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 make_cut_and_choose_challenges(election, rand_name, challenges):
""" Return random split of [0,1,...,n_reps-1] into two lists.
Use specified randomness source.
This icl/opl split will be the same for all races.
(This can be easily changed if desired.)
# icl = subset of election.k_list used for "input comparison"
# opl = subset of election.k_list used for "output production"
Save results in challenges dict.
"""
m = election.n_reps // 2
pi = sv.random_permutation(2 * m, rand_name)
pi = [pi[i] for i in range(2 * m)]
# icl = copies for input comparison
# opl = copies for output production
icl = [election.k_list[i] for i in sorted(pi[:m])]
opl = [election.k_list[i] for i in sorted(pi[m:])]
challenges['cut'] = {'icl': icl, 'opl': opl}
def make_cut_and_choose_challenges(election, rand_name, challenges):
""" Return random split of [0,1,...,n_reps-1] into two lists.
Use specified randomness source.
This icl/opl split will be the same for all races.
(This can be easily changed if desired.)
# icl = subset of election.k_list used for "input comparison"
# opl = subset of election.k_list used for "output production"
Save results in challenges dict.
"""
m = election.n_reps // 2
pi = sv.random_permutation(2*m, rand_name)
pi = [pi[i] for i in range(2*m)]
# icl = copies for input comparison
# opl = copies for output production
icl = [election.k_list[i] for i in sorted(pi[:m])]
opl = [election.k_list[i] for i in sorted(pi[m:])]
challenges['cut'] = {'icl': icl, 'opl': opl}
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 mix(self):
""" Mix votes. Information flows left to right. """
election = self.election
# replicate input to become first-column x inputs for each race & pass
for race_id in election.race_ids:
for k in election.k_list:
for i in self.row_list:
x = self.sdb[race_id][i][0]['x'] # dict of n x's
self.sdb[race_id][i][0][k]['x'] = x.copy()
# 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:
for j in range(self.cols):
rand_name = self.sdb[race_id]['a'][j]['rand_name']
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
# generate obfuscation values 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 in election.races:
race_id = race.race_id
for j in range(self.cols):
rand_name = self.sdb[race_id]['a'][j]['rand_name']
for k in election.k_list:
fuzz_dict = dict() # fuzz_dict[i][pnn]
for i in self.row_list:
fuzz_dict[i] = dict()
for v in election.p_list:
share_list = sv.share(0,
self.rows,
self.threshold,
rand_name,
race.race_modulus)
for row, i in enumerate(self.row_list):
fuzz_dict[i][v] = share_list[row][1]
for i in self.row_list:
# note that fuzz_dict[i] is dict of size n
self.sdb[race_id][i][j][k]['fuzz_dict'] = fuzz_dict[i]
# process columns left-to-right, mixing as you go
for race in self.election.races:
race_id = race.race_id
race_modulus = race.race_modulus
for j in range(self.cols):
for k in election.k_list:
for i in self.row_list:
# shuffle first
pi = self.sdb[race_id][i][j][k]['pi'] # length n
# note that pi is independent of i
x = self.sdb[race_id][i][j][k]['x'] # length n
xp = sv.apply_permutation(pi, x) # length n
# then obfuscate by adding "fuzz"
fuzz_dict = self.sdb[race_id][i][j][k]['fuzz_dict']
xpo = dict()
for v in election.p_list:
xpo[v] = (xp[v] + fuzz_dict[v]) % race_modulus
y = xpo
self.sdb[race_id][i][j][k]['y'] = y
# this column's y's become next column's x's.
# in practice would be sent via secure channels
if j < self.cols - 1:
self.sdb[race_id][i][j+1][k]['x'] = y
def mix(self):
""" Mix votes. Information flows left to right. """
election = self.election
# replicate input to become first-column x inputs for each race & pass
for race_id in election.race_ids:
for k in election.k_list:
for i in self.row_list:
x = self.sdb[race_id][i][0]['x'] # dict of n x's
self.sdb[race_id][i][0][k]['x'] = x.copy()
# 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:
for j in range(self.cols):
rand_name = self.sdb[race_id]['a'][j]['rand_name']
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
# generate obfuscation values 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 in election.races:
race_id = race.race_id
for j in range(self.cols):
rand_name = self.sdb[race_id]['a'][j]['rand_name']
for k in election.k_list:
fuzz_dict = dict() # fuzz_dict[i][pnn]
for i in self.row_list:
fuzz_dict[i] = dict()
for v in election.p_list:
share_list = sv.share(0, self.rows, self.threshold,
rand_name, race.race_modulus)
for row, i in enumerate(self.row_list):
fuzz_dict[i][v] = share_list[row][1]
for i in self.row_list:
# note that fuzz_dict[i] is dict of size n
self.sdb[race_id][i][j][k]['fuzz_dict'] = fuzz_dict[i]
# process columns left-to-right, mixing as you go
for race in self.election.races:
race_id = race.race_id
race_modulus = race.race_modulus
for j in range(self.cols):
for k in election.k_list:
for i in self.row_list:
# shuffle first
pi = self.sdb[race_id][i][j][k]['pi'] # length n
# note that pi is independent of i
x = self.sdb[race_id][i][j][k]['x'] # length n
xp = sv.apply_permutation(pi, x) # length n
# then obfuscate by adding "fuzz"
fuzz_dict = self.sdb[race_id][i][j][k]['fuzz_dict']
xpo = dict()
for v in election.p_list:
xpo[v] = (xp[v] + fuzz_dict[v]) % race_modulus
y = xpo
self.sdb[race_id][i][j][k]['y'] = y
# this column's y's become next column's x's.
# in practice would be sent via secure channels
if j < self.cols - 1:
self.sdb[race_id][i][j + 1][k]['x'] = y
