def spdz_mul(cmd: Callable, x_sh, y_sh, crypto_provider: AbstractWorker,
field: int, dtype: str):
"""Abstractly multiplies two tensors (mul or matmul)
Args:
cmd: a callable of the equation to be computed (mul or matmul)
x_sh (AdditiveSharingTensor): the left part of the operation
y_sh (AdditiveSharingTensor): the right part of the operation
crypto_provider (AbstractWorker): an AbstractWorker which is used to generate triples
field (int): an integer denoting the size of the field
dtype (str): denotes the dtype of shares
Return:
an AdditiveSharingTensor
"""
assert isinstance(x_sh, sy.AdditiveSharingTensor)
assert isinstance(y_sh, sy.AdditiveSharingTensor)
locations = x_sh.locations
torch_dtype = x_sh.torch_dtype
# Get triples
a, b, a_mul_b = request_triple(crypto_provider, cmd, field, dtype,
x_sh.shape, y_sh.shape, locations)
delta = x_sh - a
epsilon = y_sh - b
# Reconstruct and send to all workers
delta = delta.reconstruct()
epsilon = epsilon.reconstruct()
delta_epsilon = cmd(delta, epsilon)
# Trick to keep only one child in the MultiPointerTensor (like in SNN)
j1 = torch.ones(delta_epsilon.shape).type(torch_dtype).send(
locations[0], **no_wrap)
j0 = torch.zeros(delta_epsilon.shape).type(torch_dtype).send(
*locations[1:], **no_wrap)
if len(locations) == 2:
j = sy.MultiPointerTensor(children=[j1, j0])
else:
j = sy.MultiPointerTensor(children=[j1] + list(j0.child.values()))
delta_b = cmd(delta, b)
a_epsilon = cmd(a, epsilon)
res = delta_epsilon * j + delta_b + a_epsilon + a_mul_b
res = res.type(torch_dtype)
return res
def maxpool_deriv(x_sh):
"""Compute derivative of MaxPool
Args:
x_sh (AdditiveSharingTensor): the private tensor on which the op applies
Returns:
an AdditiveSharingTensor of the same shape as x_sh full of zeros except for
a 1 at the position of the max value
"""
if x_sh.dtype == "custom":
raise TypeError(
"`custom` dtype shares are unsupported in SecureNN, use dtype = `long` or `int` instead"
)
workers = x_sh.locations
crypto_provider = x_sh.crypto_provider
L = x_sh.field
dtype = get_dtype(L)
torch_dtype = get_torch_dtype(L)
n1, n2 = x_sh.shape
n = n1 * n2
if L % n != 0:
raise ValueError("Check x_sh.field and x_sh.shape ")
x_sh = x_sh.view(-1)
# Common Randomness
U_sh = _shares_of_zero(n, L, dtype, crypto_provider, *workers)
r = _random_common_value(L, *workers)
# 1)
_, ind_max_sh = maxpool(x_sh)
# 2)
j = sy.MultiPointerTensor(children=[
torch.tensor([int(i == 0)]).send(w, **no_wrap)
for i, w in enumerate(workers)
])
k_sh = ind_max_sh + j * r
# 3)
t = k_sh.get()
k = t % n
E_k = torch.zeros(n, dtype=torch_dtype)
E_k[k] = 1
E_sh = E_k.share(*workers, field=L, dtype=dtype, **no_wrap)
# 4)
g = r % n
D_sh = torch.roll(E_sh, -g)
maxpool_d_sh = D_sh + U_sh
return maxpool_d_sh.view(n1, n2)
def _random_common_value(max_value, *workers):
"""
Return n in [0, max_value-1] chosen by a worker and sent to all workers,
in the form of a MultiPointerTensor
"""
pointer = torch.LongTensor([1]).send(workers[0]).random_(max_value)
pointers = [pointer]
for worker in workers[1:]:
pointers.append(pointer.copy().move(worker))
common_value = sy.MultiPointerTensor(children=pointers)
return common_value
def _random_common_bit(*workers):
"""
Return a bit chosen by a worker and sent to all workers,
in the form of a MultiPointerTensor
"""
pointer = torch.tensor([1]).send(workers[0], **no_wrap).random_(2)
pointers = [pointer]
for worker in workers[1:]:
pointers.append(pointer.copy().move(worker))
bit = sy.MultiPointerTensor(children=pointers)
return bit
def maxpool_deriv(x_sh):
""" Compute derivative of MaxPool
Args:
x_sh (AdditiveSharingTensor): the private tensor on which the op applies
Returns:
an AdditiveSharingTensor of the same shape as x_sh full of zeros except for
a 1 at the position of the max value
"""
assert (
x_sh.dtype != "custom"
), "`custom` dtype shares are unsupported in SecureNN, use dtype = `long` or `int` instead"
alice, bob = x_sh.locations
crypto_provider = x_sh.crypto_provider
L = x_sh.field
dtype = get_dtype(L)
torch_dtype = get_torch_dtype(L)
n1, n2 = x_sh.shape
n = n1 * n2
x_sh = x_sh.view(-1)
# Common Randomness
U_sh = _shares_of_zero(n, L, dtype, crypto_provider, alice, bob)
r = _random_common_value(L, alice, bob)
# 1)
_, ind_max_sh = maxpool(x_sh)
# 2)
j = sy.MultiPointerTensor(children=[
torch.tensor([1]).send(alice, **no_wrap),
torch.tensor([0]).send(bob, **no_wrap)
])
k_sh = ind_max_sh + j * r
# 3)
t = k_sh.get()
k = t % n
E_k = torch.zeros(n, dtype=torch_dtype)
E_k[k] = 1
E_sh = E_k.share(alice, bob, field=L, dtype=dtype, **no_wrap)
# 4)
g = r % n
D_sh = torch.roll(E_sh, -g)
maxpool_d_sh = D_sh + U_sh
return maxpool_d_sh.view(n1, n2)
def test_xor_implementation(workers):
alice, bob, james = workers["alice"], workers["bob"], workers["james"]
r = decompose(th.tensor([3])).send(alice, bob).child
x_bit_sh = decompose(th.tensor([23])).share(alice, bob, crypto_provider=james).child
j0 = torch.zeros(x_bit_sh.shape).long().send(bob)
j1 = torch.ones(x_bit_sh.shape).long().send(alice)
j = syft.MultiPointerTensor(children=[j0, j1])
w = (j * r) + x_bit_sh - (2 * x_bit_sh * r)
r_real = r.virtual_get()[0]
x_real = x_bit_sh.virtual_get()
w_real = r_real + x_real - 2 * r_real * x_real
assert (w.virtual_get() == w_real).all()
def _random_common_value(max_value, *workers):
"""
Return n in [0, max_value-1] chosen by a worker and sent to all workers,
in the form of a MultiPointerTensor
"""
torch_dtype = get_torch_dtype(max_value)
pointer = (torch.tensor([1], dtype=torch_dtype).send(
workers[0], **no_wrap).random_(1, get_max_val_field(max_value)))
pointers = [pointer]
for worker in workers[1:]:
pointers.append(pointer.copy().move(worker))
common_value = sy.MultiPointerTensor(children=pointers)
return common_value
def reconstruct(self):
"""
Reconstruct the shares of the AdditiveSharingTensor remotely without
its owner being able to see any sensitive value
Returns:
A MultiPointerTensor where all workers hold the reconstructed value
"""
workers = self.locations
ptr_to_sh = self.copy().wrap().send(workers[0], **no_wrap)
pointer = ptr_to_sh.remote_get()
pointers = [pointer] + [pointer.copy().move(w) for w in workers[1:]]
return sy.MultiPointerTensor(children=pointers)
def maxpool_deriv(x_sh):
""" Compute derivative of MaxPool
Args:
x_sh (AdditiveSharingTensor): the private tensor on which the op applies
Returns:
an AdditiveSharingTensor of the same shape as x_sh full of zeros except for
a 1 at the position of the max value
"""
alice, bob = x_sh.locations
crypto_provider = x_sh.crypto_provider
L = x_sh.field
n1, n2 = x_sh.shape
n = n1 * n2
x_sh = x_sh.view(-1)
# Common Randomness
U_sh = _shares_of_zero(n, L, crypto_provider, alice, bob)
r = _random_common_value(L, alice, bob)
# 1)
_, ind_max_sh = maxpool(x_sh)
# 2)
j = sy.MultiPointerTensor(
children=[torch.tensor([1]).send(alice),
torch.tensor([0]).send(bob)])
k_sh = ind_max_sh + j * r
# 3)
t = k_sh.get()
k = t % n
E_k = torch.zeros(n)
E_k[k] = 1
E_sh = E_k.share(alice, bob).child
# 4)
g = r % n
D_sh = torch.roll(E_sh, -g)
maxpool_d_sh = D_sh + U_sh
return maxpool_d_sh.view(n1, n2)
def relu_deriv(a_sh):
"""
Compute the derivative of Relu
Args:
a_sh (AdditiveSharingTensor): the private tensor on which the op applies
Returns:
0 if Dec(a_sh) < 0
1 if Dec(a_sh) > 0
encrypted in an AdditiveSharingTensor
"""
if a_sh.dtype == "custom":
raise TypeError(
"`custom` dtype shares are unsupported in SecureNN, use dtype = `long` or `int` instead"
)
workers = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field
dtype = get_dtype(L)
torch_dtype = get_torch_dtype(L)
# Common randomness
u = _shares_of_zero(1, L, dtype, crypto_provider, *workers)
# 1)
y_sh = a_sh * 2
# 2) Not applicable with algebraic shares
y_sh = share_convert(y_sh)
# 3)
alpha_sh = msb(y_sh)
# 4)
j = sy.MultiPointerTensor(children=[
torch.tensor([int(i == 0)], dtype=torch_dtype).send(w, **no_wrap)
for i, w in enumerate(workers)
])
gamma_sh = j - alpha_sh + u
return gamma_sh
def detail(worker: AbstractWorker, tensor_tuple: tuple) -> "MultiPointerTensor":
"""
This function reconstructs a MultiPointerTensor given it's attributes in form of a tuple.
Args:
worker: the worker doing the deserialization
tensor_tuple: a tuple holding the attributes of the MultiPointerTensor
Returns:
MultiPointerTensor: a MultiPointerTensor
Examples:
multi_pointer_tensor = detail(data)
"""
tensor_id, chain = tensor_tuple
tensor = sy.MultiPointerTensor(owner=worker, id=sy.serde._detail(worker, tensor_id))
if chain is not None:
chain = sy.serde._detail(worker, chain)
tensor.child = chain
return tensor
def relu_deriv(a_sh):
"""
Compute the derivative of Relu
Args:
a_sh (AdditiveSharingTensor): the private tensor on which the op applies
Returns:
0 if Dec(a_sh) < 0
1 if Dec(a_sh) > 0
encrypted in an AdditiveSharingTensor
"""
assert (
a_sh.dtype != "custom"
), "`custom` dtype shares are unsupported in SecureNN, use dtype = `long` or `int` instead"
alice, bob = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field
dtype = get_dtype(L)
# Common randomness
u = _shares_of_zero(1, L, dtype, crypto_provider, alice, bob)
# 1)
y_sh = a_sh * 2
# 2) Not applicable with algebraic shares
y_sh = share_convert(y_sh)
# 3)
alpha_sh = msb(y_sh)
# 4)
j = sy.MultiPointerTensor(children=[
torch.tensor([0]).send(alice, **no_wrap),
torch.tensor([1]).send(bob, **no_wrap)
])
gamma_sh = j - alpha_sh + u
return gamma_sh
def relu_deriv(a_sh):
"""
Compute the derivative of Relu
Args:
a_sh (AdditiveSharingTensor): the private tensor on which the op applies
Returns:
0 if Dec(a_sh) < 0
1 if Dec(a_sh) > 0
encrypted in an AdditiveSharingTensor
"""
alice, bob = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field
# Common randomness
u = _shares_of_zero(1, L, crypto_provider, alice, bob)
# 1)
y_sh = a_sh * 2
# 2) Not applicable with algebraic shares
y_sh = share_convert(y_sh)
# y_sh.field = L - 1
# 3)
alpha_sh = msb(y_sh)
assert alpha_sh.field == L
# 4)
j = sy.MultiPointerTensor(children=[
torch.tensor([0]).send(alice, **no_wrap),
torch.tensor([1]).send(bob, **no_wrap)
])
gamma_sh = j - alpha_sh + u
assert gamma_sh.field == L
return gamma_sh
def msb(a_sh, alice, bob):
"""
Compute the most significant bit in a_sh
args:
a_sh (AdditiveSharingTensor): the tensor of study
alice (AbstractWorker): 1st worker holding a private share of a_sh
bob (AbstractWorker): 2nd worker holding a private share
return:
the most significant bit
"""
crypto_provider = a_sh.crypto_provider
L = a_sh.field
input_shape = a_sh.shape
a_sh = a_sh.view(-1)
# the commented out numbers below correspond to the
# line numbers in Table 5 of the SecureNN paper
# https://eprint.iacr.org/2018/442.pdf
# 1)
x = torch.LongTensor(a_sh.shape).random_(L - 1)
x_bit = decompose(x)
x_sh = x.share(bob, alice, crypto_provider=crypto_provider).child
# Get last column / value as decompose reverts bits: first one is in last position
x_bit_0 = x_bit[..., -1:]
x_bit_sh_0 = x_bit_0.share(bob, alice, crypto_provider=crypto_provider
).child # least -> greatest from left -> right
x_bit_sh = x_bit.share(bob, alice, crypto_provider=crypto_provider).child
# 2)
y_sh = 2 * a_sh
r_sh = y_sh + x_sh
# 3)
r = r_sh.get(
) # .send(bob, alice) #TODO: make this secure by exchanging shares remotely
r_0 = decompose(r)[..., -1].send(bob, alice).child
r = r.send(bob, alice).child
assert isinstance(r, sy.MultiPointerTensor)
j0 = torch.zeros(x_bit_sh.shape).long().send(bob)
j1 = torch.ones(x_bit_sh.shape).long().send(alice)
j = sy.MultiPointerTensor(children=[j0, j1])
j_0 = j[..., -1]
assert isinstance(j, sy.MultiPointerTensor)
assert isinstance(j_0, sy.MultiPointerTensor)
# 4)
BETA = (torch.rand(a_sh.shape) > 0.5).long().send(bob, alice).child
BETA_prime = private_compare(x_bit_sh,
r,
BETA=BETA,
j=j,
alice=alice,
bob=bob,
crypto_provider=crypto_provider).long()
# 5)
BETA_prime_sh = BETA_prime.share(bob,
alice,
crypto_provider=crypto_provider).child
# 7)
_lambda = BETA_prime_sh + (j_0 * BETA) - (2 * BETA * BETA_prime_sh)
# 8)
_delta = x_bit_sh_0.squeeze(-1) + (j_0 * r_0) - (2 * r_0 *
x_bit_sh_0.squeeze(-1))
# 9)
theta = _lambda * _delta
# 10)
u = (torch.zeros(list(theta.shape)).long().share(
alice, bob, crypto_provider=crypto_provider).child)
a = _lambda + _delta - (2 * theta) + u
return a.view(*list(input_shape))
def msb(a_sh):
"""
Compute the most significant bit in a_sh, this is an implementation of the
SecureNN paper https://eprint.iacr.org/2018/442.pdf
Args:
a_sh (AdditiveSharingTensor): the tensor of study
Return:
the most significant bit
"""
workers = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field + 1 # field of a is L - 1
dtype = get_dtype(L)
input_shape = a_sh.shape
a_sh = a_sh.view(-1)
# the commented out numbers below correspond to the
# line numbers in Table 5 of the SecureNN paper
# https://eprint.iacr.org/2018/442.pdf
# Common Randomness
beta = _random_common_bit(*workers)
u = _shares_of_zero(1, L, dtype, crypto_provider, *workers)
# 1)
x = torch.tensor(a_sh.shape).random_(get_max_val_field(L - 1))
x_bit = decompose(x, L)
x_sh = x.share(*workers,
field=L - 1,
dtype="custom",
crypto_provider=crypto_provider,
**no_wrap)
x_bit_0 = x_bit[..., 0]
x_bit_sh_0 = x_bit_0.share(*workers,
field=L,
crypto_provider=crypto_provider,
**no_wrap)
x_bit_sh = x_bit.share(*workers,
field=p,
dtype="custom",
crypto_provider=crypto_provider,
**no_wrap)
# 2)
y_sh = a_sh * 2
r_sh = y_sh + x_sh
# 3)
r = r_sh.reconstruct(
) # convert an additive sharing in multi pointer Tensor
r_0 = decompose(r, L)[..., 0]
# 4)
beta_prime = private_compare(x_bit_sh, r, beta, L)
# 5)
beta_prime_sh = beta_prime.share(*workers,
field=L,
dtype=dtype,
crypto_provider=crypto_provider,
**no_wrap)
# 7)
j = sy.MultiPointerTensor(children=[
torch.tensor([int(i == 0)]).send(w, **no_wrap)
for i, w in enumerate(workers)
])
gamma = beta_prime_sh + (j * beta) - (2 * beta * beta_prime_sh)
# 8)
delta = x_bit_sh_0 + (j * r_0) - (2 * r_0 * x_bit_sh_0)
# 9)
theta = gamma * delta
# 10)
a = gamma + delta - (theta * 2) + u
if len(input_shape):
return a.view(*list(input_shape))
else:
return a
def private_compare(x_bit_sh, r, beta, L):
"""
Perform privately x > r
args:
x (AdditiveSharedTensor): the private tensor
r (MultiPointerTensor): the threshold commonly held by the workers
beta (MultiPointerTensor): a boolean commonly held by the workers to
hide the result of computation for the crypto provider
L(int): field size for r
return:
β′ = β ⊕ (x > r).
"""
assert isinstance(x_bit_sh, sy.AdditiveSharingTensor)
assert isinstance(r, sy.MultiPointerTensor)
assert isinstance(beta, sy.MultiPointerTensor)
# Would it be safer to have a different r/beta for each value in the tensor?
workers = x_bit_sh.locations
crypto_provider = x_bit_sh.crypto_provider
p = x_bit_sh.field
# the commented out numbers below correspond to the
# line numbers in Algorithm 3 of the SecureNN paper
# https://eprint.iacr.org/2018/442.pdf
# Common randomess
s = torch.randint(1, p, x_bit_sh.shape).send(*workers, **no_wrap)
u = torch.randint(1, p, x_bit_sh.shape).send(*workers, **no_wrap)
perm = torch.randperm(x_bit_sh.shape[-1]).send(*workers, **no_wrap)
j = sy.MultiPointerTensor(children=[
torch.tensor([int(i == 0)]).send(w, **no_wrap)
for i, w in enumerate(workers)
])
# 1)
t = r + 1
t_bit = decompose(t, L)
r_bit = decompose(r, L)
# if beta == 0
# 5)
w = x_bit_sh + (j * r_bit) - (2 * r_bit * x_bit_sh)
# 6)
wc = w.flip(-1).cumsum(-1).flip(-1) - w
c_beta0 = -x_bit_sh + (j * r_bit) + j + wc
# elif beta == 1 AND r != 2^l- 1
# 8)
w = x_bit_sh + (j * t_bit) - (2 * t_bit * x_bit_sh)
# 9)
wc = w.flip(-1).cumsum(-1).flip(-1) - w
c_beta1 = x_bit_sh + (-j * t_bit) + j + wc
# else
# 11)
c_igt1 = (1 - j) * (u + 1) - (j * u)
c_ie1 = (1 - 2 * j) * u
l1_mask = torch.zeros(x_bit_sh.shape).long()
l1_mask[..., 0] = 1
l1_mask = l1_mask.send(*workers, **no_wrap)
# c_else = if i == 1 c_ie1 else c_igt1
c_else = (l1_mask * c_ie1) + ((1 - l1_mask) * c_igt1)
# Mask for the case r == 2^l −1
r_mask = (r == get_r_mask(L)).long()
r_mask = r_mask.unsqueeze(-1)
# Mask combination to execute the if / else statements of 4), 7), 10)
c = (1 - beta) * c_beta0 + (beta *
(1 - r_mask)) * c_beta1 + (beta *
r_mask) * c_else
# 14)
# Hide c values
mask = s * c
# Permute the mask
# I have to create idx because Ellipsis are still not supported
# (I would like to do permuted_mask = mask[..., perm])
idx = [slice(None)] * (len(x_bit_sh.shape) - 1) + [perm]
permuted_mask = mask[idx]
# Send it to another worker
# We do this because we can't allow the local worker to get and see permuted_mask
# because otherwise it can inverse the permutation and remove s to get c.
# So opening the permuted_mask should be made by a worker which doesn't have access
# to the randomness
remote_mask = permuted_mask.wrap().send(crypto_provider, **no_wrap)
# 15)
d_ptr = remote_mask.remote_get()
beta_prime = (d_ptr == 0).sum(-1)
# Get result back
res = beta_prime.get()
return res
def send(
self,
*location,
inplace: bool = False,
# local_autograd=False,
# preinitialize_grad=False,
no_wrap=False,
garbage_collect_data=True,
):
"""Gets the pointer to a new remote object.
One of the most commonly used methods in PySyft, this method serializes
the object upon which it is called (self), sends the object to a remote
worker, creates a pointer to that worker, and then returns that pointer
from this function.
Args:
location: The BaseWorker object which you want to send this object
to. Note that this is never actually the BaseWorker but instead
a class which instantiates the BaseWorker abstraction.
inplace: if true,
return the same object instance, else a new wrapper
# local_autograd: Use autograd system on the local machine instead
of TensorFlow's autograd on the workers.
# preinitialize_grad: Initialize gradient for AutogradTensors
to a tensor
no_wrap: If True, wrap() is called on the created pointer
garbage_collect_data: argument passed down to create_pointer()
Returns:
A tf.EagerTensor[PointerTensor] pointer to self. Note that this
object will likely be wrapped by a tf.EagerTensor wrapper.
"""
# If you send a pointer p1, you want the pointer to pointer p2
# to control the garbage collection and not the remaining old
# p1 (here self). Because if p2 is not GCed, GCing p1 shouldn't delete
# the remote tensor, but if you want to do so, as p2 is not GCed,
# you can still do `del p2`. This allows to chain multiple
# .send().send() calls.
if len(location) == 1:
location = location[0]
if hasattr(self, "child") and isinstance(self.child,
PointerTensor):
self.child.garbage_collect_data = False
ptr = self.owner.send(self,
location,
garbage_collect_data=garbage_collect_data)
ptr.description = self.description
ptr.tags = self.tags
# The last pointer should control remote GC,
# not the previous self.ptr
if hasattr(self, "ptr") and self.ptr is not None:
ptr_ = self.ptr()
if ptr_ is not None:
ptr_.garbage_collect_data = False
# we need to cache this weak reference to the pointer so that
# if this method gets called multiple times we can simply re-use
# the same pointer which was previously created
self.ptr = weakref.ref(ptr)
if inplace:
self.set_() # TODO[jason]: pretty sure this is torch specific
self.child = ptr
return self
else:
output = (ptr if no_wrap else ptr.wrap(type=tf.Variable,
initial_value=[]))
else:
children = list()
for loc in location:
children.append(self.send(loc, no_wrap=True))
output = syft.MultiPointerTensor(children=children)
if not no_wrap:
output = output.wrap(type=tf.Variable, initial_value=[])
return output
def send(
self,
*location,
inplace: bool = False,
user: object = None,
local_autograd: bool = False,
requires_grad: bool = False,
preinitialize_grad: bool = False,
no_wrap: bool = False,
garbage_collect_data: bool = True,
):
"""Gets the pointer to a new remote object.
One of the most commonly used methods in PySyft, this method serializes the object upon
which it is called (self), sends the object to a remote worker, creates a pointer to
that worker, and then returns that pointer from this function.
Args:
location: The BaseWorker object which you want to send this object to. Note that
this is never actually the BaseWorker but instead a class which instantiates the
BaseWorker abstraction.
inplace: if true, return the same object instance, else a new wrapper
user (object,optional): User credentials to be verified.
local_autograd: Use autograd system on the local machine instead of PyTorch's
autograd on the workers.
requires_grad: Default to False. If true, whenever the remote value of this tensor
will have its gradient updated (for example when calling .backward()), a call
will be made to set back the local gradient value.
preinitialize_grad: Initialize gradient for AutogradTensors to a tensor
no_wrap: If True, wrap() is called on the created pointer
garbage_collect_data: argument passed down to create_pointer()
Returns:
A torch.Tensor[PointerTensor] pointer to self. Note that this
object will likely be wrapped by a torch.Tensor wrapper.
Raises:
SendNotPermittedError: Raised if send is not permitted on this tensor.
"""
# If you send a pointer p1, you want the pointer to pointer p2 to control
# the garbage collection and not the remaining old p1 (here self). Because if
# p2 is not GCed, GCing p1 shouldn't delete the remote tensor, but if you
# want to do so, as p2 is not GCed, you can still do `del p2`.
# This allows to chain multiple .send().send() calls.
if len(location) == 1:
location = location[0]
if self.has_child() and isinstance(self.child, PointerTensor):
self.child.garbage_collect_data = False
if self._is_parameter():
self.data.child.garbage_collect_data = False
ptr = self.owner.send(
self,
location,
local_autograd=local_autograd,
requires_grad=requires_grad,
preinitialize_grad=preinitialize_grad,
garbage_collect_data=garbage_collect_data,
)
ptr.description = self.description
ptr.tags = self.tags
# The last pointer should control remote GC, not the previous self.ptr
if hasattr(self, "ptr") and self.ptr is not None:
ptr_ = self.ptr()
if ptr_ is not None:
ptr_.garbage_collect_data = False
# we need to cache this weak reference to the pointer so that
# if this method gets called multiple times we can simply re-use
# the same pointer which was previously created
self.ptr = weakref.ref(ptr)
if self._is_parameter():
if inplace:
self.is_wrapper = True
with torch.no_grad():
self.set_()
self.data = ptr
output = self
else:
if no_wrap:
raise ValueError(
"Parameters can't accept no_wrap=True")
wrapper = torch.Tensor()
param_wrapper = torch.nn.Parameter(wrapper)
param_wrapper.is_wrapper = True
with torch.no_grad():
param_wrapper.set_()
param_wrapper.data = ptr
output = param_wrapper
else:
if inplace:
self.is_wrapper = True
self.set_()
self.child = ptr
return self
else:
output = ptr if no_wrap else ptr.wrap()
if self.requires_grad:
# This is for AutogradTensor to work on MultiPointerTensors
# With pre-initialized gradients, this should get it from AutogradTensor.grad
if preinitialize_grad:
grad = output.child.grad
else:
grad = output.attr("grad")
output.grad = grad
# Because of the way PyTorch works, .grad is prone to
# create entirely new Python objects for the tensor, which
# inadvertently deletes our custom attributes (like .child)
# But, if we keep a backup reference around, PyTorch seems
# to re-use it, which means .grad keeps the attributes we
# want it to keep. #HackAlert
output.backup_grad = grad
if local_autograd:
output = syft.AutogradTensor(
data=output,
preinitialize_grad=preinitialize_grad).on(output)
else:
children = []
for loc in location:
children.append(self.clone().send(loc, no_wrap=True))
output = syft.MultiPointerTensor(children=children)
if not no_wrap:
output = output.wrap()
return output
def share_convert(a_sh):
"""
Convert shares of a in field L to shares of a in field L - 1
Args:
a_sh (AdditiveSharingTensor): the additive sharing tensor who owns
the shares in field L to convert
Return:
An additive sharing tensor with shares in field L-1
"""
assert isinstance(a_sh, sy.AdditiveSharingTensor)
workers = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field
# Common randomness
eta_pp = _random_common_bit(*workers)
r = _random_common_value(L, *workers)
# Share remotely r
r_sh = ((r * 1).child[workers[0].id].share(
*workers, field=L, crypto_provider=crypto_provider).get().child)
r_shares = r_sh.child
alpha0 = ((r_shares[workers[0].id] +
r_shares[workers[1].id].copy().move(workers[0])) >= L).long()
alpha1 = alpha0.copy().move(workers[1])
alpha = sy.MultiPointerTensor(children=[alpha0, alpha1])
u_sh = _shares_of_zero(1, L - 1, crypto_provider, *workers)
# 2)
a_tilde_sh = a_sh + r_sh
a_shares = a_sh.child
beta0 = ((a_shares[workers[0].id] + r_shares[workers[0].id]) >= L).long()
beta1 = ((a_shares[workers[1].id] + r_shares[workers[1].id]) >= L).long()
beta = sy.MultiPointerTensor(children=[beta0, beta1])
# 4)
a_tilde_shares = a_tilde_sh.child
delta = ((a_tilde_shares[workers[0].id].copy().get() +
a_tilde_shares[workers[1].id].copy().get()) >= L).long()
x = a_tilde_sh.get() % L
# 5)
x_bit = decompose(x)
x_bit_sh = x_bit.share(*workers,
field=p,
crypto_provider=crypto_provider,
**no_wrap)
delta_sh = delta.share(*workers,
field=L - 1,
crypto_provider=crypto_provider,
**no_wrap)
# 6)
eta_p = private_compare(x_bit_sh, r - 1, eta_pp)
# 7)
eta_p_sh = eta_p.share(*workers,
field=L - 1,
crypto_provider=crypto_provider,
**no_wrap)
# 9)
j = sy.MultiPointerTensor(children=[
torch.tensor([0]).send(workers[0], **no_wrap),
torch.tensor([1]).send(workers[1], **no_wrap),
])
eta_sh = eta_p_sh + (1 - j) * eta_pp - 2 * eta_pp * eta_p_sh
# 10)
theta_sh = beta - (1 - j) * (alpha + 1) + delta_sh + eta_sh
# 11)
y_sh = -theta_sh + a_sh + u_sh
return y_sh
def share_convert_long(a_sh):
"""
Convert shares of a in field L to shares of a in field L - 1
Args:
a_sh (AdditiveSharingTensor): the additive sharing tensor who owns
the shares in field L to convert
Return:
An additive sharing tensor with shares in field L-1
"""
assert isinstance(a_sh, sy.AdditiveSharingTensor)
assert (
a_sh.dtype != "custom"
), "`custom` dtype shares are unsupported in SecureNN, use dtype = `long` or `int` instead"
workers = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field
torch_dtype = get_torch_dtype(L)
dtype = get_dtype(L)
# Common randomness
eta_pp = _random_common_bit(*workers, dtype=torch_dtype)
r = _random_common_value(L, *workers)
# Share remotely r
r_sh = ((r * 1).child[workers[0].id].share(
*workers, field=L, dtype=dtype,
crypto_provider=crypto_provider).get().child)
r_shares = r_sh.child
# WORKS WITH N PARTIES, NEEDS BUGFIXING IN WRAP
# alpha0 = wrap(r_sh, L)
# alphas = [alpha0.copy().move(w) for w in workers[1:]]
# alpha = sy.MultiPointerTensor(children=[alpha0, *alphas])
# WORKS WITH 2 PARTIES
alpha0 = (((r_shares[workers[0].id] +
r_shares[workers[1].id].copy().move(workers[0])) >
get_max_val_field(L))).type(torch_dtype)
alpha1 = alpha0.copy().move(workers[1])
alpha = sy.MultiPointerTensor(children=[alpha0, alpha1])
u_sh = _shares_of_zero(1, L, "custom", crypto_provider, *workers)
# 2)
a_tilde_sh = a_sh + r_sh
a_shares = a_sh.child
beta0 = (((a_shares[workers[0].id] + r_shares[workers[0].id]) >
get_max_val_field(L)) +
((a_shares[workers[0].id] + r_shares[workers[0].id]) <
get_min_val_field(L))).type(torch_dtype)
beta1 = (((a_shares[workers[1].id] + r_shares[workers[1].id]) >
get_max_val_field(L)) +
((a_shares[workers[1].id] + r_shares[workers[1].id]) <
get_min_val_field(L))).type(torch_dtype)
beta = sy.MultiPointerTensor(children=[beta0, beta1])
# 4)
a_tilde_shares = a_tilde_sh.child
delta = a_tilde_shares[workers[0].id].copy().get() + a_tilde_shares[
workers[1].id].copy().get()
# Check for both positive and negative overflows
delta = ((delta > get_max_val_field(L)) +
(delta < get_min_val_field(L))).type(torch_dtype)
x = a_tilde_sh.get()
# 5)
x_bit = decompose(x, L)
x_bit_sh = x_bit.share(*workers,
field=p,
dtype="custom",
crypto_provider=crypto_provider,
**no_wrap)
delta_sh = delta.share(*workers,
field=L - 1,
dtype="custom",
crypto_provider=crypto_provider,
**no_wrap)
# 6)
eta_p = private_compare(x_bit_sh, r - 1, eta_pp, L)
# 7)
eta_p_sh = eta_p.share(*workers,
field=L - 1,
dtype="custom",
crypto_provider=crypto_provider,
**no_wrap)
# 9)
j = sy.MultiPointerTensor(children=[
torch.tensor([int(i != 0)]).send(w, **no_wrap)
for i, w in enumerate(workers)
])
eta_sh = eta_p_sh + (1 - j) * eta_pp - 2 * eta_pp * eta_p_sh
# 10)
theta_sh = beta - (1 - j) * (alpha + 1) + delta_sh + eta_sh
# 11)
# NOTE:
# It seems simple operation with shares in L-1 field is enough to conver a_sh from L to L-1
# Conversion of shares is handled internally in AST ops for custom dtype
y_sh = u_sh + a_sh + theta_sh
return y_sh
def send(self,
*location,
inplace: bool = False,
no_wrap=False,
garbage_collect_data=True):
"""Gets the pointer to a new remote object.
One of the most commonly used methods in PySyft, this method serializes
the object upon which it is called (self), sends the object to a remote
worker, creates a pointer to that worker, and then returns that pointer
from this function.
Args:
location: The BaseWorker object which you want to send this object
to. Note that this is never actually the BaseWorker but instead
a class which instantiates the BaseWorker abstraction.
inplace: if true,
return the same object instance, else a new wrapper
no_wrap: If True, wrap() is called on the created pointer
garbage_collect_data: argument passed down to create_pointer()
Returns:
A tf.keras.layers.Layer[ObjectPointer] pointer to self. Note that this
object will likely be wrapped by a ttf.keras.layers.Layer wrapper.
"""
# If you send a pointer p1, you want the pointer to pointer p2
# to control the garbage collection and not the remaining old
# p1 (here self). Because if p2 is not GCed, GCing p1 shouldn't delete
# the remote keras object, but if you want to do so, as p2 is not GCed,
# you can still do `del p2`. This allows to chain multiple
# .send().send() calls.
if len(location) == 1:
location = location[0]
ptr = self.owner.send(self,
location,
garbage_collect_data=garbage_collect_data)
ptr.description = self.description
ptr.tags = self.tags
# The last pointer should control remote GC,
# not the previous self.ptr
if hasattr(self, "ptr") and self.ptr is not None:
ptr_ = self.ptr()
if ptr_ is not None:
ptr_.garbage_collect_data = False
# we need to cache this weak reference to the pointer so that
# if this method gets called multiple times we can simply re-use
# the same pointer which was previously created
self.ptr = weakref.ref(ptr)
if inplace:
self.child = ptr
return self
else:
output = ptr if no_wrap else ptr.wrap(
type=tf.keras.models.Model)
else:
# TODO [Yann] check if we would want to send the keras
# object to several workers this way.
children = list()
for loc in location:
children.append(self.send(loc, no_wrap=True))
output = syft.MultiPointerTensor(children=children)
if not no_wrap:
output = output.wrap(type=tf.keras.models.Model)
return output
def msb(a_sh):
"""
Compute the most significant bit in a_sh, this is an implementation of the
SecureNN paper https://eprint.iacr.org/2018/442.pdf
Args:
a_sh (AdditiveSharingTensor): the tensor of study
Return:
the most significant bit
"""
alice, bob = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field + 1 # field of a is L - 1
input_shape = a_sh.shape
a_sh = a_sh.view(-1)
# the commented out numbers below correspond to the
# line numbers in Table 5 of the SecureNN paper
# https://eprint.iacr.org/2018/442.pdf
# Common Randomness
beta = _random_common_bit(alice, bob)
u = _shares_of_zero(1, L, crypto_provider, alice, bob)
# 1)
x = torch.LongTensor(a_sh.shape).random_(L - 1)
x_bit = decompose(x)
x_sh = x.share(bob, alice, field=L - 1,
crypto_provider=crypto_provider).child
x_bit_0 = x_bit[..., 0]
x_bit_sh_0 = x_bit_0.share(bob,
alice,
field=L,
crypto_provider=crypto_provider).child
x_bit_sh = x_bit.share(bob,
alice,
field=p,
crypto_provider=crypto_provider).child
# 2)
y_sh = a_sh * 2
r_sh = y_sh + x_sh
# 3)
r = r_sh.reconstruct() % (
L - 1) # convert an additive sharing in multi pointer Tensor
r_0 = decompose(r)[..., 0]
# 4)
beta_prime = private_compare(x_bit_sh, r, beta=beta)
# 5)
beta_prime_sh = beta_prime.share(bob,
alice,
field=L,
crypto_provider=crypto_provider).child
# 7)
j = sy.MultiPointerTensor(
children=[torch.tensor([0]).send(alice),
torch.tensor([1]).send(bob)])
gamma = beta_prime_sh + (j * beta) - (2 * beta * beta_prime_sh)
# 8)
delta = x_bit_sh_0 + (j * r_0) - (2 * r_0 * x_bit_sh_0)
# 9)
theta = gamma * delta
# 10)
a = gamma + delta - (theta * 2) + u
if len(input_shape):
return a.view(*list(input_shape))
else:
return a
def msb(a_sh):
"""
Compute the most significant bit in a_sh, this is an implementation of the
SecureNN paper https://eprint.iacr.org/2018/442.pdf
Args:
a_sh (AdditiveSharingTensor): the tensor of study
Return:
the most significant bit
"""
alice, bob = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field + 1 # field of a is L - 1
input_shape = a_sh.shape
a_sh = a_sh.view(-1)
# the commented out numbers below correspond to the
# line numbers in Table 5 of the SecureNN paper
# https://eprint.iacr.org/2018/442.pdf
# Common Randomness
BETA = _random_common_bit(alice, bob)
u = torch.zeros(1).long().share(alice,
bob,
field=L,
crypto_provider=crypto_provider).child
# 1)
x = torch.LongTensor(a_sh.shape).random_(L - 1)
x_bit = decompose(x)
x_sh = x.share(bob, alice, field=L - 1,
crypto_provider=crypto_provider).child
x_bit_0 = x_bit[
...,
-1] # Get last value as decompose reverts bits: 1st one is in last position
x_bit_sh_0 = x_bit_0.share(bob,
alice,
field=L,
crypto_provider=crypto_provider
).child # least -> greatest from left -> right
x_bit_sh = x_bit.share(bob,
alice,
field=p,
crypto_provider=crypto_provider).child
# 2)
y_sh = 2 * a_sh
r_sh = y_sh + x_sh
# 3)
r = r_sh.reconstruct(
) # convert an additive sharing in multi pointer Tensor
r_0 = decompose(r)[..., -1]
# 4)
BETA_prime = private_compare(x_bit_sh, r, BETA=BETA)
# 5)
BETA_prime_sh = BETA_prime.share(bob,
alice,
field=L,
crypto_provider=crypto_provider).child
# 7)
j = sy.MultiPointerTensor(
children=[torch.tensor([0]).send(alice),
torch.tensor([1]).send(bob)])
gamma = BETA_prime_sh + (j * BETA) - (2 * BETA * BETA_prime_sh)
# 8)
delta = x_bit_sh_0 + (j * r_0) - (2 * r_0 * x_bit_sh_0)
# 9)
theta = gamma * delta
# 10)
a = gamma + delta - (2 * theta) + u
if len(input_shape):
return a.view(*list(input_shape))
else:
return a
def share_convert(a_sh):
"""
Convert shares of a in field L to shares of a in field L - 1
Args:
a_sh (AdditiveSharingTensor): the additive sharing tensor who owns
the shares in field L to convert
Return:
An additive sharing tensor with shares in field L-1
"""
assert isinstance(a_sh, sy.AdditiveSharingTensor)
workers = a_sh.locations
crypto_provider = a_sh.crypto_provider
L = a_sh.field
# Common randomness
eta_pp = _random_common_bit(*workers)
r = _random_common_value(L, *workers)
# Share remotely r
r_sh = ((r * 1).child[workers[0].id].share(
*workers, field=L, crypto_provider=crypto_provider).get().child)
r_shares = r_sh.child
alpha = (
((r_shares[workers[0].id] +
(r_shares[workers[1].id] * 1).move(workers[0])).get() >=
L).long().send(*workers).child
) # FIXME security issue: the local worker learns alpha while this should be avoided
u_sh = (torch.zeros(1).long().send(workers[0]).share(
*workers, field=L - 1, crypto_provider=crypto_provider).get().child)
# 2)
a_tilde_sh = a_sh + r_sh
a_shares = a_sh.child
ptr0 = a_shares[workers[0].id] + r_shares[workers[0].id]
beta0 = (
(a_shares[workers[0].id] + r_shares[workers[0].id]) >= L).long() - (
(a_shares[workers[0].id] + r_shares[workers[0].id]) < 0).long()
ptr1 = a_shares[workers[1].id] + r_shares[workers[1].id]
beta1 = (
(a_shares[workers[1].id] + r_shares[workers[1].id]) >= L).long() - (
(a_shares[workers[1].id] + r_shares[workers[1].id]) < 0).long()
beta = sy.MultiPointerTensor(children=[beta0.long(), beta1.long()])
# 4)
a_tilde_shares = a_tilde_sh.child
delta = (((a_tilde_shares[workers[0].id] * 1).get() +
(a_tilde_shares[workers[1].id] * 1).get()) >= L).long()
x = a_tilde_sh.get()
# 5)
x_bit = decompose(x)
x_bit_sh = x_bit.share(*workers, field=p,
crypto_provider=crypto_provider).child
delta_sh = delta.share(*workers,
field=L - 1,
crypto_provider=crypto_provider).child
# 6)
eta_p = private_compare(x_bit_sh, r, eta_pp)
# 7)
eta_p_sh = eta_p.share(*workers,
field=L - 1,
crypto_provider=crypto_provider).child
# 9)
j = sy.MultiPointerTensor(children=[
torch.tensor([0]).send(workers[0]),
torch.tensor([1]).send(workers[1])
])
eta_sh = eta_p_sh + (1 - j) * eta_pp - 2 * eta_pp * eta_p_sh
# 10)
theta_sh = beta - (1 - j) * (alpha + 1) + delta_sh + eta_sh
# 11)
y_sh = a_sh - theta_sh + u_sh
y_sh.field = L - 1
return y_sh
def private_compare(x, r, BETA):
"""
Perform privately x > r
args:
x (AdditiveSharedTensor): the private tensor
r (MultiPointerTensor): the threshold commonly held by alice and bob
BETA (MultiPointerTensor): a boolean commonly held by alice and bob to
hide the result of computation for the crypto provider
return:
β′ = β ⊕ (x > r).
"""
assert isinstance(x, sy.AdditiveSharingTensor)
assert isinstance(r, sy.MultiPointerTensor)
assert isinstance(BETA, sy.MultiPointerTensor)
alice, bob = x.locations
crypto_provider = x.crypto_provider
p = x.field
L = 2**Q_BITS # 2**l
# the commented out numbers below correspond to the
# line numbers in Algorithm 3 of the SecureNN paper
# https://eprint.iacr.org/2018/442.pdf
# 1)
t = (r + 1) % L
# Mask for the case r == 2^l −1
R_MASK = (r == (L - 1)).long()
r = decompose(r)
t = decompose(t)
# Mask for beta
BETA = BETA.unsqueeze(1).expand(list(r.shape))
R_MASK = R_MASK.unsqueeze(1).expand(list(r.shape))
u = (torch.rand(x.shape) > 0.5).long().send(bob, alice).child
# Mask for condition i̸=1 in 11)
l1_mask = torch.zeros(x.shape).long()
l1_mask[:, -1:] = 1
l1_mask = l1_mask.send(bob, alice).child
# if BETA == 0
# 5)
j0 = torch.zeros(x.shape).long().send(bob)
j1 = torch.ones(x.shape).long().send(alice)
j = sy.MultiPointerTensor(children=[j0, j1])
w = (j * r) + x - (2 * x * r)
# 6)
wf = flip(w, 1)
wfc = wf.cumsum(1) - wf
wfcf = flip(wfc, 1)
c_beta0 = (j * r) - x + j + wfcf
# elif BETA == 1 AND r != 2^l- 1
# 8)
w = x + (j * t) - (2 * t * x) # FIXME: unused
# 9)
c_beta1 = (-j * t) + x + j + wfcf
# else
# 11)
c_igt1 = (1 - j) * (u + 1) - (j * u)
c_ie1 = (j * -2) + 1
c_21l = (l1_mask * c_ie1) + ((1 - l1_mask) * c_igt1)
# Mask combination to execute the if / else statements of 4), 7), 10)
c = (1 - BETA) * c_beta0 + BETA * c_beta1
c = (c * (1 - R_MASK)) + (c_21l * R_MASK)
# 14)
# Hide c values
s = torch.randint(1, p, c.shape).send(alice, bob).child
mask = s * c
# Permute the mask
perm = torch.randperm(c.shape[1]).send(alice, bob).child
permuted_mask = mask[:, perm]
# Send it to another worker
remote_mask = permuted_mask.wrap().send(crypto_provider)
# 15)
# transform remotely the AdditiveSharingTensor back to a torch tensor
d_ptr = remote_mask.remote_get()
beta_prime = (d_ptr == 0).sum(1)
# Get result back
res = beta_prime.get()
return res