Files
MP-SPDZ/Compiler/permutation.py
2020-03-20 20:31:25 +11:00

496 lines
15 KiB
Python

from random import randint
import math
#import sys
#from Test.core import *
if '_Array' not in dir():
from Compiler.types import *
from Compiler.types import _secret
from Compiler.library import *
from Compiler.program import Program
_Array = Array
SORT_BITS = []
def predefined_comparator(x, y):
""" Assumes SORT_BITS is populated with the required sorting network bits """
if predefined_comparator.sort_bits_iter is None:
predefined_comparator.sort_bits_iter = iter(SORT_BITS)
return next(predefined_comparator.sort_bits_iter)
predefined_comparator.sort_bits_iter = None
def list_comparator(x, y):
""" Uses the first element in the list for comparison """
return x[0] < y[0]
def normal_comparator(x, y):
return x < y
def bitwise_list_comparator(x, y):
""" Uses the first element in the list for comparison """
return (1 - x[0]) * y[0]
def bitwise_comparator(x, y):
b = (1 - x) * y
return b
def cond_swap_bit(x,y, b):
""" swap if b == 1 """
if x is None:
return y, None
elif y is None:
return x, None
if isinstance(x, list):
t = [(xi - yi) * b for xi,yi in zip(x, y)]
return [xi - ti for xi,ti in zip(x, t)], \
[yi + ti for yi,ti in zip(y, t)]
else:
t = (x - y) * b
return x - t, y + t
def cond_swap(x,y, comp):
if x is None:
return y, None
elif y is None:
return x, None
b = comp(x, y)
return cond_swap_bit(x, y, 1 - b)
def odd_even_merge(a, comp):
if len(a) & (len(a)-1) != 0:
raise Exception('Length must be a power of 2')
if len(a) == 1:
return
if len(a) == 2:
a[0], a[1] = cond_swap(a[0], a[1], comp)
else:
even = a[::2]
odd = a[1::2]
odd_even_merge(even, comp)
odd_even_merge(odd, comp)
a[0] = even[0]
for i in range(1, len(a) // 2):
a[2*i-1], a[2*i] = cond_swap(odd[i-1], even[i], comp)
a[-1] = odd[-1]
def odd_even_merge_sort(a, comp=bitwise_comparator):
if len(a) == 1:
return
elif len(a) % 2 == 0:
lower = a[:len(a)//2]
upper = a[len(a)//2:]
odd_even_merge_sort(lower, comp)
odd_even_merge_sort(upper, comp)
a[:] = lower + upper
odd_even_merge(a, comp)
else:
raise CompilerError('Length of list must be power of two')
def merge(a, b, comp):
""" General length merge (pads to power of 2) """
while len(a) & (len(a)-1) != 0:
a.append(None)
while len(b) & (len(b)-1) != 0:
b.append(None)
if len(a) < len(b):
a += [None] * (len(b) - len(a))
elif len(b) < len(a):
b += [None] * (len(b) - len(b))
t = a + b
odd_even_merge(t, comp)
for i,v in enumerate(t[::]):
if v is None:
t.remove(None)
return t
def sort(a, comp):
""" Pads to power of 2, sorts, removes padding """
length = len(a)
while len(a) & (len(a)-1) != 0:
a.append(None)
odd_even_merge_sort(a, comp)
del a[length:]
def recursive_merge(a, comp):
""" Recursively merge a list of sorted lists (initially sorted by size) """
if len(a) == 1:
return
# merge smallest two lists, place result in correct position, recurse
t = merge(a[0], a[1], comp)
del a[0]
del a[0]
added = False
for i,c in enumerate(a):
if len(c) >= len(t):
a.insert(i, t)
added = True
break
if not added:
a.append(t)
recursive_merge(a, comp)
def random_perm(n):
""" Generate a random permutation of length n
WARNING: randomness fixed at compile-time, this is NOT secure
"""
if not Program.prog.options.insecure:
raise CompilerError('no secure implementation of Waksman permution, '
'use --insecure to activate')
a = list(range(n))
for i in range(n-1, 0, -1):
j = randint(0, i)
t = a[i]
a[i] = a[j]
a[j] = t
return a
def inverse(perm):
inv = [None] * len(perm)
for i, p in enumerate(perm):
inv[p] = i
return inv
def configure_waksman(perm):
n = len(perm)
if n == 2:
return [(perm[0], perm[0])]
I = [None] * (n//2)
O = [None] * (n//2)
p0 = [None] * (n//2)
p1 = [None] * (n//2)
inv_perm = [0] * n
for i, p in enumerate(perm):
inv_perm[p] = i
while True:
try:
j = 2 * O.index(None)
except ValueError:
break
#print 'j =', j
O[j//2] = 0
via = 0
j0 = j
while True:
#print ' I[%d] = %d' % (inv_perm[j]/2, ((inv_perm[j] % 2) + via) % 2)
i = inv_perm[j]
#print ' p0[%d] = %d' % (inv_perm[j]/2, j/2)
p0[i//2] = j//2
I[i//2] = i % 2
O[j//2] = j % 2
#print ' O[%d] = %d' % (j/2, j % 2)
if i % 2 == 1:
i -= 1
else:
i += 1
#i, via = set_swapper(I, j, via, inv_perm)
#print ' O[%d] = %d' % (perm[i]/2, ((perm[i] % 2) + via ) % 2)
j = perm[i]
#O[j/2] = j % 2
if j % 2 == 1:
j -= 1
else:
j += 1
#j, via = set_swapper(O, i, via, perm)
#print ' p1[%d] = %d' % (i/2, perm[i]/2)
p1[i//2] = perm[i]//2
#print ' i = %d, j = %d' %(i,j)
if j == j0:
break
if None not in p0 and None not in p1:
break
assert sorted(p0) == list(range(n//2))
assert sorted(p1) == list(range(n//2))
p0_config = configure_waksman(p0)
p1_config = configure_waksman(p1)
return [I + O] + [a+b for a,b in zip(p0_config, p1_config)]
def waksman(a, config, depth=0, start=0, reverse=False):
""" config is a list of log_2(n) configuration lists for the sub-networks """
n = len(a)
if n == 2:
a[0], a[1] = cond_swap_bit(a[0], a[1], config[depth][start])
return
a0 = [0] * (n//2)
a1 = [0] * (n//2)
for i in range(n//2):
if reverse:
a0[i], a1[i] = cond_swap_bit(a[2*i], a[2*i+1], config[depth][i + n//2 + start])
else:
a0[i], a1[i] = cond_swap_bit(a[2*i], a[2*i+1], config[depth][i + start])
waksman(a0, config, depth+1, start, reverse)
waksman(a1, config, depth+1, start + n//2, reverse)
for i in range(n//2):
if reverse:
a[2*i], a[2*i+1] = cond_swap_bit(a0[i], a1[i], config[depth][i + start])
else:
a[2*i], a[2*i+1] = cond_swap_bit(a0[i], a1[i], config[depth][i + n//2 + start])
WAKSMAN_FUNCTIONS = {}
def iter_waksman(a, config, reverse=False):
""" Iterative Waksman algorithm, compilable for large inputs. Input
must be an Array. """
n = len(a)
#if not isinstance(a, Array):
# raise CompilerError('Input must be an Array')
depth = MemValue(0)
nblocks = MemValue(1)
size = MemValue(0)
a2 = Array(n, a[0].reg_type)
#config_array = Array(n, a[0].reg_type)
#reverse = (int(reverse))
def create_round_fn(n, reg_type, inwards):
if (n, reg_type, inwards, reverse) in WAKSMAN_FUNCTIONS:
return WAKSMAN_FUNCTIONS[(n, reg_type, inwards, reverse)]
def do_round(size, config_address, a_address, a2_address):
A = Array(n, reg_type, a_address)
A2 = Array(n, reg_type, a2_address)
C = Array(n, reg_type, config_address)
outwards = 1 - inwards
sizeval = size
#for k in range(n//2):
@for_range_parallel(200, n//2)
def f(k):
j = cint(k) % sizeval
i = (cint(k) - j)//sizeval
base = 2*i*sizeval
in1, in2 = (base+j+j*inwards), (base+j+j*inwards+1*inwards+sizeval*outwards)
out1, out2 = (base+j+j*outwards), (base+j+j*outwards+1*outwards+sizeval*inwards)
if inwards:
if reverse:
c = C[base + j + sizeval]
else:
c = C[base + j]
else:
if reverse:
c = C[base + j]
else:
c = C[base + j + sizeval]
A2[out1], A2[out2] = cond_swap_bit(A[in1], A[in2], c)
fn = function_block(do_round)
WAKSMAN_FUNCTIONS[(n, reg_type, inwards, reverse)] = fn
return fn
do_round = lambda size, ca, aa, aa2, inwards: \
create_round_fn(n, a[0].reg_type, inwards)(size, ca, aa, aa2)
logn = int(math.log(n,2))
# going into middle of network
@for_range(logn)
def f(i):
size.write(n//(2*nblocks))
conf_address = MemValue(config.address + depth.read()*n)
do_round(size, conf_address, a.address, a2.address, 1)
@for_range(n)
def _(i):
a[i] = a2[i]
nblocks.write(nblocks*2)
depth.write(depth+1)
nblocks.write(nblocks//4)
depth.write(depth-2)
# and back out
@for_range(logn-1)
def f(i):
size.write(n//(2*nblocks))
conf_address = MemValue(config.address + depth.read()*n)
do_round(size, conf_address, a.address, a2.address, 0)
@for_range(n)
def _(i):
a[i] = a2[i]
nblocks.write(nblocks//2)
depth.write(depth-1)
## going into middle of network
#while nblocks < n:
# #for i in range(n):
# # config_array[i] = config[depth][i].read()
#
# size.write(n/(2*nblocks))
# conf_address = config.address + depth*n
# do_round_in(size, conf_address, a.address, a2.address)
#
# for i in range(n):
# a[i] = a2[i]
#
# nblocks *= 2
# depth += 1
#
#nblocks /= 4
#depth -= 2
## and back out
#while nblocks > 0:
# #for i in range(n):
# # config_array[i] = config[depth][i].read()
#
# size.write(n/(2*nblocks))
# conf_address = config.address + depth*n
# do_round_out(size, conf_address, a.address, a2.address)
#
# for i in range(n):
# a[i] = a2[i]
#
# nblocks /= 2
# depth -= 1
def rec_shuffle(x, config=None, value_type=sgf2n, reverse=False):
n = len(x)
if n & (n-1) != 0:
raise CompilerError('shuffle requires n a power of 2')
if config is None:
config = configure_waksman(random_perm(n))
for i,c in enumerate(config):
config[i] = [value_type.bit_type(b) for b in c]
waksman(x, config, reverse=reverse)
waksman(x, config, reverse=reverse)
def config_shuffle(n, value_type):
""" Compute config for oblivious shuffling.
Take mod 2 for active sec. """
perm = random_perm(n)
if n & (n-1) != 0:
# pad permutation to power of 2
m = 2**int(math.ceil(math.log(n, 2)))
perm += list(range(n, m))
config_bits = configure_waksman(perm)
# 2-D array
config = Array(len(config_bits) * len(perm), value_type.reg_type)
if n > 1024:
for x in config_bits:
for y in x:
get_program().public_input(y)
@for_range(sum(len(x) for x in config_bits))
def _(i):
config[i] = public_input()
return config
for i,c in enumerate(config_bits):
for j,b in enumerate(c):
config[i * len(perm) + j] = b
return config
def shuffle(x, config=None, value_type=sgf2n, reverse=False):
""" Simulate secure shuffling with Waksman network for 2 players.
WARNING: This is not a properly secure implementation but has roughly the right complexity.
Returns the network switching config so it may be re-used later. """
n = len(x)
m = 2**int(math.ceil(math.log(n, 2)))
assert n == m, 'only working for powers of two'
if config is None:
config = config_shuffle(n, value_type)
if isinstance(x, list):
if isinstance(x[0], list):
length = len(x[0])
assert len(x) == length
for i in range(length):
xi = Array(m, value_type.reg_type)
for j in range(n):
xi[j] = x[j][i]
for j in range(n, m):
xi[j] = value_type(0)
iter_waksman(xi, config, reverse=reverse)
iter_waksman(xi, config, reverse=reverse)
for j, y in enumerate(xi):
x[j][i] = y
else:
xa = Array(m, value_type.reg_type)
for i in range(n):
xa[i] = x[i]
for i in range(n, m):
xa[i] = value_type(0)
iter_waksman(xa, config, reverse=reverse)
iter_waksman(xa, config, reverse=reverse)
x[:] = xa
elif isinstance(x, Array):
if len(x) != m and config is None:
raise CompilerError('Non-power of 2 Array input not yet supported')
iter_waksman(x, config, reverse=reverse)
iter_waksman(x, config, reverse=reverse)
else:
raise CompilerError('Invalid type for shuffle:', type(x))
return config
def shuffle_entries(x, entry_cls, config=None, value_type=sgf2n, reverse=False, perm_size=None):
""" Shuffle a list of ORAM entries.
Randomly permutes the first "perm_size" entries, leaving the rest (empty
entry padding) in the same position. """
n = len(x)
l = len(x[0])
if n & (n-1) != 0:
raise CompilerError('Entries must be padded to power of two length.')
if perm_size is None:
perm_size = n
xarrays = [Array(n, value_type.reg_type) for i in range(l)]
for i in range(n):
for j,value in enumerate(x[i]):
if isinstance(value, MemValue):
xarrays[j][i] = value.read()
else:
xarrays[j][i] = value
if config is None:
config = config_shuffle(perm_size, value_type)
for xi in xarrays:
shuffle(xi, config, value_type, reverse)
for i in range(n):
x[i] = entry_cls(xarrays[j][i] for j in range(l))
return config
def sort_zeroes(bits, x, n_ones, value_type):
""" Return Array of values in "x" where the corresponding bit in "bits" is
a 0.
The total number of zeroes in "bits" must be known.
"bits" and "x" must be Arrays. """
config = config_shuffle(len(x), value_type)
shuffle(bits, config=config, value_type=value_type)
shuffle(x, config=config, value_type=value_type)
result = Array(n_ones, value_type.reg_type)
sz = MemValue(0)
last_x = MemValue(value_type(0))
#for i,b in enumerate(bits):
#if_then(b.reveal() == 0)
#result[sz.read()] = x[i]
#sz += 1
#end_if()
@for_range(len(bits))
def f(i):
found = (bits[i].reveal() == 0)
szval = sz.read()
result[szval] = last_x + (x[i] - last_x) * found
sz.write(sz + found)
last_x.write(result[szval])
return result