class MPCTensor(CrypTensor):
def __init__(self,
tensor,
ptype=Ptype.arithmetic,
device=None,
*args,
**kwargs):
"""
Creates the shared tensor from the input `tensor` provided by party `src`.
The `ptype` defines the type of sharing used (default: arithmetic).
The other parties can specify a `tensor` or `size` to determine the size
of the shared tensor object to create. In this case, all parties must
specify the same (tensor) size to prevent the party's shares from varying
in size, which leads to undefined behavior.
Alternatively, the parties can set `broadcast_size` to `True` to have the
`src` party broadcast the correct size. The parties who do not know the
tensor size beforehand can provide an empty tensor as input. This is
guaranteed to produce correct behavior but requires an additional
communication round.
The parties can also set the `precision` and `device` for their share of
the tensor. If `device` is unspecified, it is set to `tensor.device`.
"""
if tensor is None:
raise ValueError("Cannot initialize tensor with None.")
# take required_grad from kwargs, input tensor, or set to False:
default = tensor.requires_grad if torch.is_tensor(tensor) else False
requires_grad = kwargs.pop("requires_grad", default)
# call CrypTensor constructor:
super().__init__(requires_grad=requires_grad)
if device is None and hasattr(tensor, "device"):
device = tensor.device
# create the MPCTensor:
tensor_type = ptype.to_tensor()
if tensor is []:
self._tensor = torch.tensor([], device=device)
else:
self._tensor = tensor_type(tensor=tensor,
device=device,
*args,
**kwargs)
self.ptype = ptype
@staticmethod
def new(*args, **kwargs):
"""
Creates a new MPCTensor, passing all args and kwargs into the constructor.
"""
return MPCTensor(*args, **kwargs)
@staticmethod
def from_shares(share, precision=None, src=0, ptype=Ptype.arithmetic):
result = MPCTensor([])
from_shares = ptype.to_tensor().from_shares
result._tensor = from_shares(share, precision=precision, src=src)
result.ptype = ptype
return result
def clone(self):
"""Create a deep copy of the input tensor."""
# TODO: Rename this to __deepcopy__()?
result = MPCTensor([])
result._tensor = self._tensor.clone()
result.ptype = self.ptype
return result
def shallow_copy(self):
"""Create a shallow copy of the input tensor."""
# TODO: Rename this to __copy__()?
result = MPCTensor([])
result._tensor = self._tensor
result.ptype = self.ptype
return result
def copy_(self, other):
"""Copies value of other MPCTensor into this MPCTensor."""
assert isinstance(other, MPCTensor), "other must be MPCTensor"
self._tensor.copy_(other._tensor)
self.ptype = other.ptype
def to(self, *args, **kwargs):
r"""
Depending on the input arguments,
converts underlying share to the given ptype or
performs `torch.to` on the underlying torch tensor
To convert underlying share to the given ptype, call `to` as:
to(ptype, **kwargs)
It will call MPCTensor.to_ptype with the arguments provided above.
Otherwise, `to` performs `torch.to` on the underlying
torch tensor. See
https://pytorch.org/docs/stable/tensors.html?highlight=#torch.Tensor.to
for a reference of the parameters that can be passed in.
Args:
ptype: Ptype.arithmetic or Ptype.binary.
"""
if "ptype" in kwargs:
return self._to_ptype(**kwargs)
elif args and isinstance(args[0], Ptype):
ptype = args[0]
return self._to_ptype(ptype, **kwargs)
else:
share = self.share.to(*args, **kwargs)
if share.is_cuda:
share = CUDALongTensor(share)
self.share = share
return self
def _to_ptype(self, ptype, **kwargs):
r"""
Convert MPCTensor's underlying share to the corresponding ptype
(ArithmeticSharedTensor, BinarySharedTensor)
Args:
ptype (Ptype.arithmetic or Ptype.binary): The ptype to convert
the shares to.
precision (int, optional): Precision of the fixed point encoder when
converting a binary share to an arithmetic share. It will be ignored
if the ptype doesn't match.
bits (int, optional): If specified, will only preserve the bottom `bits` bits
of a binary tensor when converting from a binary share to an arithmetic share.
It will be ignored if the ptype doesn't match.
"""
retval = self.clone()
if retval.ptype == ptype:
return retval
retval._tensor = convert(self._tensor, ptype, **kwargs)
retval.ptype = ptype
return retval
def arithmetic(self):
"""Converts self._tensor to arithmetic secret sharing"""
return self.to(Ptype.arithmetic)
def binary(self):
"""Converts self._tensor to binary secret sharing"""
return self.to(Ptype.binary)
@property
def device(self):
"""Return the `torch.device` of the underlying share"""
return self.share.device
@property
def is_cuda(self):
"""Return True if the underlying share is stored on GPU, False otherwise"""
return self.share.is_cuda
def cuda(self, *args, **kwargs):
"""Call `torch.Tensor.cuda` on the underlying share"""
self.share = CUDALongTensor(self.share.cuda(*args, **kwargs))
return self
def cpu(self):
"""Call `torch.Tensor.cpu` on the underlying share"""
self.share = self.share.cpu()
return self
def get_plain_text(self, dst=None):
"""Decrypts the tensor."""
return self._tensor.get_plain_text(dst=dst)
def reveal(self, dst=None):
"""Decrypts the tensor without any downscaling."""
return self._tensor.reveal(dst=dst)
def __bool__(self):
"""Override bool operator since encrypted tensors cannot evaluate"""
raise RuntimeError("Cannot evaluate MPCTensors to boolean values")
def __nonzero__(self):
"""__bool__ for backwards compatibility with Python 2"""
raise RuntimeError("Cannot evaluate MPCTensors to boolean values")
def __repr__(self):
"""Returns a representation of the tensor useful for debugging."""
from crypten.debug import debug_mode
share = self.share
plain_text = self._tensor.get_plain_text() if debug_mode(
) else "HIDDEN"
ptype = self.ptype
return (f"MPCTensor(\n\t_tensor={share}\n"
f"\tplain_text={plain_text}\n\tptype={ptype}\n)")
def __setitem__(self, index, value):
"""Set tensor values by index"""
if not isinstance(value, MPCTensor):
value = MPCTensor(value, ptype=self.ptype, device=self.device)
self._tensor.__setitem__(index, value._tensor)
@property
def share(self):
"""Returns underlying share"""
return self._tensor.share
@share.setter
def share(self, value):
"""Sets share to value"""
self._tensor.share = value
@property
def encoder(self):
"""Returns underlying encoder"""
return self._tensor.encoder
@encoder.setter
def encoder(self, value):
"""Sets encoder to value"""
self._tensor.encoder = value
@staticmethod
def __cat_stack_helper(op, tensors, *args, **kwargs):
assert op in ["cat", "stack"], "Unsupported op for helper function"
assert isinstance(tensors, list), "%s input must be a list" % op
assert len(tensors) > 0, "expected a non-empty list of MPCTensors"
_ptype = kwargs.pop("ptype", None)
# Populate ptype field
if _ptype is None:
for tensor in tensors:
if isinstance(tensor, MPCTensor):
_ptype = tensor.ptype
break
if _ptype is None:
_ptype = Ptype.arithmetic
# Make all inputs MPCTensors of given ptype
for i, tensor in enumerate(tensors):
if tensor.ptype != _ptype:
tensors[i] = tensor.to(_ptype)
# Operate on all input tensors
result = tensors[0].clone()
funcs = {"cat": torch_cat, "stack": torch_stack}
result.share = funcs[op]([tensor.share for tensor in tensors], *args,
**kwargs)
return result
@staticmethod
def cat(tensors, *args, **kwargs):
"""Perform matrix concatenation"""
return MPCTensor.__cat_stack_helper("cat", tensors, *args, **kwargs)
@staticmethod
def stack(tensors, *args, **kwargs):
"""Perform tensor stacking"""
return MPCTensor.__cat_stack_helper("stack", tensors, *args, **kwargs)
@staticmethod
def rand(*sizes, device=None):
"""
Returns a tensor with elements uniformly sampled in [0, 1). The uniform
random samples are generated by generating random bits using fixed-point
encoding and converting the result to an ArithmeticSharedTensor.
"""
rand = MPCTensor([])
encoder = FixedPointEncoder()
rand._tensor = BinarySharedTensor.rand(*sizes,
bits=encoder._precision_bits)
rand._tensor.encoder = encoder
rand.ptype = Ptype.binary
return rand.to(Ptype.arithmetic, bits=encoder._precision_bits)
@staticmethod
def randn(*sizes, device=None):
"""
Returns a tensor with normally distributed elements. Samples are
generated using the Box-Muller transform with optimizations for
numerical precision and MPC efficiency.
"""
u = MPCTensor.rand(*sizes).flatten()
odd_numel = u.numel() % 2 == 1
if odd_numel:
u = MPCTensor.cat([u, MPCTensor.rand((1, ))])
n = u.numel() // 2
u1 = u[:n]
u2 = u[n:]
# Radius = sqrt(- 2 * log(u1))
r2 = -2 * u1.log(input_in_01=True)
r = r2.sqrt()
# Theta = cos(2 * pi * u2) or sin(2 * pi * u2)
cos, sin = u2.sub(0.5).mul(6.28318531).cossin()
# Generating 2 independent normal random variables using
x = r.mul(sin)
y = r.mul(cos)
z = MPCTensor.cat([x, y])
if odd_numel:
z = z[1:]
return z.view(*sizes)
def bernoulli(self):
"""Returns a tensor with elements in {0, 1}. The i-th element of the
output will be 1 with probability according to the i-th value of the
input tensor."""
return self > MPCTensor.rand(self.size(), device=self.device)
# TODO: It seems we can remove all Dropout implementations below?
def dropout(self, p=0.5, training=True, inplace=False):
r"""
Randomly zeroes some of the elements of the input tensor with
probability :attr:`p`.
Args:
p: probability of a channel to be zeroed. Default: 0.5
training: apply dropout if is ``True``. Default: ``True``
inplace: If set to ``True``, will do this operation in-place.
Default: ``False``
"""
assert p >= 0.0 and p <= 1.0, "dropout probability has to be between 0 and 1"
if not training:
if inplace:
return self
else:
return self.clone()
rand_tensor = MPCTensor.rand(self.size(), device=self.device)
dropout_tensor = rand_tensor > p
if inplace:
result_tensor = self.mul_(dropout_tensor).div_(1 - p)
else:
result_tensor = self.mul(dropout_tensor).div_(1 - p)
return result_tensor
def dropout2d(self, p=0.5, training=True, inplace=False):
r"""
Randomly zero out entire channels (a channel is a 2D feature map,
e.g., the :math:`j`-th channel of the :math:`i`-th sample in the
batched input is a 2D tensor :math:`\text{input}[i, j]`) of the input tensor).
Each channel will be zeroed out independently on every forward call with
probability :attr:`p` using samples from a Bernoulli distribution.
Args:
p: probability of a channel to be zeroed. Default: 0.5
training: apply dropout if is ``True``. Default: ``True``
inplace: If set to ``True``, will do this operation in-place.
Default: ``False``
"""
assert p >= 0.0 and p <= 1.0, "dropout probability has to be between 0 and 1"
return self._feature_dropout(p, training, inplace)
def dropout3d(self, p=0.5, training=True, inplace=False):
r"""
Randomly zero out entire channels (a channel is a 3D feature map,
e.g., the :math:`j`-th channel of the :math:`i`-th sample in the
batched input is a 3D tensor :math:`\text{input}[i, j]`) of the input tensor).
Each channel will be zeroed out independently on every forward call with
probability :attr:`p` using samples from a Bernoulli distribution.
Args:
p: probability of a channel to be zeroed. Default: 0.5
training: apply dropout if is ``True``. Default: ``True``
inplace: If set to ``True``, will do this operation in-place.
Default: ``False``
"""
# This is 100% the same code as dropout2d. We duplicate this code so that
# stack traces are not confusing.
assert p >= 0.0 and p <= 1.0, "dropout probability has to be between 0 and 1"
return self._feature_dropout(p, training, inplace)
def _feature_dropout(self, p=0.5, training=True, inplace=False):
"""Randomly zeros out entire channels in the input tensor with probability
:attr:`p`. (a channel is a nD feature map, e.g., the :math:`j`-th channel
of the :math:`i`-th sample in the batched input is a nD tensor
:math:`\text{input}[i, j]`)."""
assert self.dim(
) >= 2, "feature dropout requires dimension to be at least 2"
assert p >= 0.0 and p <= 1.0, "dropout probability has to be between 0 and 1"
if not training:
if inplace:
return self
else:
return self.clone()
# take first 2 dimensions
feature_dropout_size = self.size()[0:2]
# create dropout tensor over the first two dimensions
rand_tensor = MPCTensor.rand(feature_dropout_size, device=self.device)
feature_dropout_tensor = rand_tensor > p
# Broadcast to remaining dimensions
for i in range(2, self.dim()):
feature_dropout_tensor = feature_dropout_tensor.unsqueeze(i)
feature_dropout_tensor.share, self.share = torch.broadcast_tensors(
feature_dropout_tensor.share, self.share)
if inplace:
result_tensor = self.mul_(feature_dropout_tensor).div_(1 - p)
else:
result_tensor = self.mul(feature_dropout_tensor).div_(1 - p)
return result_tensor
# Comparators
@mode(Ptype.binary)
def _ltz(self, _scale=True):
"""Returns 1 for elements that are < 0 and 0 otherwise"""
shift = torch.iinfo(torch.long).bits - 1
result = (self >> shift).to(Ptype.arithmetic, bits=1)
if _scale:
return result * result.encoder._scale
else:
result.encoder._scale = 1
return result
@mode(Ptype.arithmetic)
def ge(self, y, _scale=True):
"""Returns self >= y"""
return 1 - self.lt(y, _scale=_scale)
@mode(Ptype.arithmetic)
def gt(self, y, _scale=True):
"""Returns self > y"""
return (-self + y)._ltz(_scale=_scale)
@mode(Ptype.arithmetic)
def le(self, y, _scale=True):
"""Returns self <= y"""
return 1 - self.gt(y, _scale=_scale)
@mode(Ptype.arithmetic)
def lt(self, y, _scale=True):
"""Returns self < y"""
return (self - y)._ltz(_scale=_scale)
@mode(Ptype.arithmetic)
def eq(self, y, _scale=True):
"""Returns self == y"""
if comm.get().get_world_size() == 2:
return (self - y)._eqz_2PC(_scale=_scale)
return 1 - self.ne(y, _scale=_scale)
@mode(Ptype.arithmetic)
def ne(self, y, _scale=True):
"""Returns self != y"""
if comm.get().get_world_size() == 2:
return 1 - self.eq(y, _scale=_scale)
difference = self - y
difference.share = torch_stack([difference.share, -(difference.share)])
return difference._ltz(_scale=_scale).sum(0)
@mode(Ptype.arithmetic)
def _eqz_2PC(self, _scale=True):
"""Returns self == 0"""
# Create BinarySharedTensors from shares
x0 = MPCTensor(self.share, src=0, ptype=Ptype.binary)
x1 = MPCTensor(-self.share, src=1, ptype=Ptype.binary)
# Perform equality testing using binary shares
x0._tensor = x0._tensor.eq(x1._tensor)
x0.encoder = x0.encoder if _scale else self.encoder
# Convert to Arithmetic sharing
result = x0.to(Ptype.arithmetic, bits=1)
if not _scale:
result.encoder._scale = 1
return result
@mode(Ptype.arithmetic)
def sign(self, _scale=True):
"""Computes the sign value of a tensor (0 is considered positive)"""
return 1 - 2 * self._ltz(_scale=_scale)
@mode(Ptype.arithmetic)
def abs(self):
"""Computes the absolute value of a tensor"""
return self * self.sign(_scale=False)
@mode(Ptype.arithmetic)
def relu(self):
"""Compute a Rectified Linear function on the input tensor."""
return self * self.ge(0, _scale=False)
@mode(Ptype.arithmetic)
def weighted_index(self, dim=None):
"""
Returns a tensor with entries that are one-hot along dimension `dim`.
These one-hot entries are set at random with weights given by the input
`self`.
Examples::
>>> encrypted_tensor = MPCTensor(torch.tensor([1., 6.]))
>>> index = encrypted_tensor.weighted_index().get_plain_text()
# With 1 / 7 probability
torch.tensor([1., 0.])
# With 6 / 7 probability
torch.tensor([0., 1.])
"""
if dim is None:
return self.flatten().weighted_index(dim=0).view(self.size())
x = self.cumsum(dim)
max_weight = x.index_select(
dim, torch.tensor(x.size(dim) - 1, device=self.device))
r = MPCTensor.rand(max_weight.size(), device=self.device) * max_weight
gt = x.gt(r, _scale=False)
shifted = gt.roll(1, dims=dim)
shifted.share.index_fill_(dim, torch.tensor(0, device=self.device), 0)
return gt - shifted
@mode(Ptype.arithmetic)
def weighted_sample(self, dim=None):
"""
Samples a single value across dimension `dim` with weights corresponding
to the values in `self`
Returns the sample and the one-hot index of the sample.
Examples::
>>> encrypted_tensor = MPCTensor(torch.tensor([1., 6.]))
>>> index = encrypted_tensor.weighted_sample().get_plain_text()
# With 1 / 7 probability
(torch.tensor([1., 0.]), torch.tensor([1., 0.]))
# With 6 / 7 probability
(torch.tensor([0., 6.]), torch.tensor([0., 1.]))
"""
indices = self.weighted_index(dim)
sample = self.mul(indices).sum(dim)
return sample, indices
# max / min-related functions
@mode(Ptype.arithmetic)
def argmax(self, dim=None, keepdim=False, one_hot=True):
"""Returns the indices of the maximum value of all elements in the
`input` tensor.
"""
# TODO: Make dim an arg.
if self.dim() == 0:
result = (MPCTensor(torch.ones(
(), device=self.device)) if one_hot else MPCTensor(
torch.zeros((), device=self.device)))
return result
result = _argmax_helper(self,
dim,
one_hot,
config.max_method,
_return_max=False)
if not one_hot:
result = _one_hot_to_index(result, dim, keepdim, self.device)
return result
@mode(Ptype.arithmetic)
def argmin(self, dim=None, keepdim=False, one_hot=True):
"""Returns the indices of the minimum value of all elements in the
`input` tensor.
"""
# TODO: Make dim an arg.
return (-self).argmax(dim=dim, keepdim=keepdim, one_hot=one_hot)
@mode(Ptype.arithmetic)
def max(self, dim=None, keepdim=False, one_hot=True):
"""Returns the maximum value of all elements in the input tensor."""
# TODO: Make dim an arg.
method = config.max_method
if dim is None:
if method in ["log_reduction", "double_log_reduction"]:
# max_result can be obtained directly
max_result = _max_helper_all_tree_reductions(self,
method=method)
else:
# max_result needs to be obtained through argmax
with ConfigManager("max_method", method):
argmax_result = self.argmax(one_hot=True)
max_result = self.mul(argmax_result).sum()
return max_result
else:
argmax_result, max_result = _argmax_helper(self,
dim=dim,
one_hot=True,
method=method,
_return_max=True)
if max_result is None:
max_result = (self * argmax_result).sum(dim=dim,
keepdim=keepdim)
if keepdim:
max_result = (max_result.unsqueeze(dim)
if max_result.dim() < self.dim() else max_result)
if one_hot:
return max_result, argmax_result
else:
return (
max_result,
_one_hot_to_index(argmax_result, dim, keepdim,
self.device),
)
@mode(Ptype.arithmetic)
def min(self, dim=None, keepdim=False, one_hot=True):
"""Returns the minimum value of all elements in the input tensor."""
# TODO: Make dim an arg.
result = (-self).max(dim=dim, keepdim=keepdim, one_hot=one_hot)
if dim is None:
return -result
else:
return -result[0], result[1]
@mode(Ptype.arithmetic)
def max_pool2d(self,
kernel_size,
padding=None,
stride=None,
return_indices=False):
"""Applies a 2D max pooling over an input signal composed of several
input planes.
"""
max_input = self.shallow_copy()
max_input.share, output_size = pool_reshape(
self.share,
kernel_size,
padding=padding,
stride=stride,
# padding with extremely negative values to avoid choosing pads
# -2 ** 33 is acceptable since it is lower than the supported range
# which is -2 ** 32 because multiplication can otherwise fail.
pad_value=(-(2**33)),
)
max_vals, argmax_vals = max_input.max(dim=-1, one_hot=True)
max_vals = max_vals.view(output_size)
if return_indices:
if isinstance(kernel_size, int):
kernel_size = (kernel_size, kernel_size)
argmax_vals = argmax_vals.view(output_size + kernel_size)
return max_vals, argmax_vals
return max_vals
@mode(Ptype.arithmetic)
def _max_pool2d_backward(self,
indices,
kernel_size,
padding=None,
stride=None,
output_size=None):
"""Implements the backwards for a `max_pool2d` call."""
# Setup padding
if padding is None:
padding = 0
if isinstance(padding, int):
padding = padding, padding
assert isinstance(padding,
tuple), "padding must be a int, tuple, or None"
p0, p1 = padding
# Setup stride
if stride is None:
stride = kernel_size
if isinstance(stride, int):
stride = stride, stride
assert isinstance(padding,
tuple), "stride must be a int, tuple, or None"
s0, s1 = stride
# Setup kernel_size
if isinstance(kernel_size, int):
kernel_size = kernel_size, kernel_size
assert isinstance(padding, tuple), "padding must be a int or tuple"
k0, k1 = kernel_size
assert self.dim(
) == 4, "Input to _max_pool2d_backward must have 4 dimensions"
assert (
indices.dim() == 6
), "Indices input for _max_pool2d_backward must have 6 dimensions"
# Computes one-hot gradient blocks from each output variable that
# has non-zero value corresponding to the argmax of the corresponding
# block of the max_pool2d input.
kernels = self.view(self.size() + (1, 1)) * indices
# Use minimal size if output_size is not specified.
if output_size is None:
output_size = (
self.size(0),
self.size(1),
s0 * self.size(2) - 2 * p0,
s1 * self.size(3) - 2 * p1,
)
# Sum the one-hot gradient blocks at corresponding index locations.
result = MPCTensor(torch.zeros(output_size)).pad([p0, p0, p1, p1])
for i in range(self.size(2)):
for j in range(self.size(3)):
left_ind = s0 * i
top_ind = s1 * j
result[:, :, left_ind:left_ind + k0,
top_ind:top_ind + k1] += kernels[:, :, i, j]
result = result[:, :, p0:result.size(2) - p0, p1:result.size(3) - p1]
return result
def adaptive_avg_pool2d(self, output_size):
r"""
Applies a 2D adaptive average pooling over an input signal composed of
several input planes.
See :class:`~torch.nn.AdaptiveAvgPool2d` for details and output shape.
Args:
output_size: the target output size (single integer or
double-integer tuple)
"""
resized_input, args, kwargs = adaptive_pool2d_helper(self,
output_size,
reduction="mean")
return resized_input.avg_pool2d(*args, **kwargs)
def adaptive_max_pool2d(self, output_size, return_indices=False):
r"""Applies a 2D adaptive max pooling over an input signal composed of
several input planes.
See :class:`~torch.nn.AdaptiveMaxPool2d` for details and output shape.
Args:
output_size: the target output size (single integer or
double-integer tuple)
return_indices: whether to return pooling indices. Default: ``False``
"""
resized_input, args, kwargs = adaptive_pool2d_helper(self,
output_size,
reduction="max")
return resized_input.max_pool2d(*args,
**kwargs,
return_indices=return_indices)
def where(self, condition, y):
"""Selects elements from self or y based on condition
Args:
condition (torch.bool or MPCTensor): when True yield self,
otherwise yield y
y (torch.tensor or MPCTensor): values selected at indices
where condition is False.
Returns: MPCTensor or torch.tensor
"""
if is_tensor(condition):
condition = condition.float()
y_masked = y * (1 - condition)
else:
# encrypted tensor must be first operand
y_masked = (1 - condition) * y
return self * condition + y_masked
@mode(Ptype.arithmetic)
def pad(self, pad, mode="constant", value=0):
result = self.shallow_copy()
if isinstance(value, MPCTensor):
result._tensor = self._tensor.pad(pad,
mode=mode,
value=value._tensor)
else:
result._tensor = self._tensor.pad(pad, mode=mode, value=value)
return result
@mode(Ptype.arithmetic)
def polynomial(self, coeffs, func="mul"):
"""Computes a polynomial function on a tensor with given coefficients,
`coeffs`, that can be a list of values or a 1-D tensor.
Coefficients should be ordered from the order 1 (linear) term first,
ending with the highest order term. (Constant is not included).
"""
# Coefficient input type-checking
if isinstance(coeffs, list):
coeffs = torch.tensor(coeffs, device=self.device)
assert is_tensor(coeffs) or crypten.is_encrypted_tensor(
coeffs), "Polynomial coefficients must be a list or tensor"
assert coeffs.dim(
) == 1, "Polynomial coefficients must be a 1-D tensor"
# Handle linear case
if coeffs.size(0) == 1:
return self.mul(coeffs)
# Compute terms of polynomial using exponentially growing tree
terms = crypten.stack([self, self.square()])
while terms.size(0) < coeffs.size(0):
highest_term = terms.index_select(
0, torch.tensor(terms.size(0) - 1, device=self.device))
new_terms = getattr(terms, func)(highest_term)
terms = crypten.cat([terms, new_terms])
# Resize the coefficients for broadcast
terms = terms[:coeffs.size(0)]
for _ in range(terms.dim() - 1):
coeffs = coeffs.unsqueeze(1)
# Multiply terms by coefficients and sum
return terms.mul(coeffs).sum(0)
def div(self, y):
r"""Divides each element of :attr:`self` with the scalar :attr:`y` or
each element of the tensor :attr:`y` and returns a new resulting tensor.
For `y` a scalar:
.. math::
\text{out}_i = \frac{\text{self}_i}{\text{y}}
For `y` a tensor:
.. math::
\text{out}_i = \frac{\text{self}_i}{\text{y}_i}
Note for :attr:`y` a tensor, the shapes of :attr:`self` and :attr:`y` must be
`broadcastable`_.
.. _broadcastable:
https://pytorch.org/docs/stable/notes/broadcasting.html#broadcasting-semantics""" # noqa: B950
result = self.clone()
if isinstance(y, CrypTensor):
result.share = torch.broadcast_tensors(result.share,
y.share)[0].clone()
elif is_tensor(y):
result.share = torch.broadcast_tensors(result.share, y)[0].clone()
return result.div_(y)
def div_(self, y):
"""In-place version of :meth:`div`"""
if isinstance(y, MPCTensor):
return self.mul_(y.reciprocal())
self._tensor.div_(y)
return self
def pow(self, p, **kwargs):
"""
Computes an element-wise exponent `p` of a tensor, where `p` is an
integer.
"""
if isinstance(p, float) and int(p) == p:
p = int(p)
if not isinstance(p, int):
raise TypeError(
"pow must take an integer exponent. For non-integer powers, use"
" pos_pow with positive-valued base.")
if p < -1:
return self.reciprocal().pow(-p)
elif p == -1:
return self.reciprocal()
elif p == 0:
# Note: This returns 0 ** 0 -> 1 when inputs have zeros.
# This is consistent with PyTorch's pow function.
return MPCTensor(torch.ones_like(self.share))
elif p == 1:
return self.clone()
elif p == 2:
return self.square()
elif p % 2 == 0:
return self.square().pow(p // 2)
else:
return self.square().mul_(self).pow((p - 1) // 2)
def pow_(self, p, **kwargs):
"""In-place version of pow_ function"""
result = self.pow(p)
self.share.set_(result.share.data)
return self
def pos_pow(self, p):
"""
Approximates self ** p by computing: :math:`x^p = exp(p * log(x))`
Note that this requires that the base `self` contain only positive values
since log can only be computed on positive numbers.
Note that the value of `p` can be an integer, float, public tensor, or
encrypted tensor.
"""
if isinstance(p, int) or (isinstance(p, float) and int(p) == p):
return self.pow(p)
return self.log().mul_(p).exp()
def norm(self, p="fro", dim=None, keepdim=False):
"""Computes the p-norm of the input tensor (or along a dimension)."""
if p == "fro":
p = 2
if isinstance(p, (int, float)):
assert p >= 1, "p-norm requires p >= 1"
if p == 1:
if dim is None:
return self.abs().sum()
return self.abs().sum(dim, keepdim=keepdim)
elif p == 2:
if dim is None:
return self.square().sum().sqrt()
return self.square().sum(dim, keepdim=keepdim).sqrt()
elif p == float("inf"):
if dim is None:
return self.abs().max()
return self.abs().max(dim=dim, keepdim=keepdim)[0]
else:
if dim is None:
return self.abs().pos_pow(p).sum().pos_pow(1 / p)
return self.abs().pos_pow(p).sum(dim, keepdim=keepdim).pos_pow(
1 / p)
elif p == "nuc":
raise NotImplementedError("Nuclear norm is not implemented")
else:
raise ValueError(f"Improper value p ({p})for p-norm")
def index_add(self, dim, index, tensor):
"""Performs out-of-place index_add: Accumulate the elements of tensor into the
self tensor by adding to the indices in the order given in index.
"""
return self.clone().index_add_(dim, index, tensor)
def index_add_(self, dim, index, tensor):
"""Performs in-place index_add: Accumulate the elements of tensor into the
self tensor by adding to the indices in the order given in index.
"""
assert index.dim() == 1, "index needs to be a vector"
public = isinstance(tensor, (int, float)) or is_tensor(tensor)
private = isinstance(tensor, MPCTensor)
if public:
self._tensor.index_add_(dim, index, tensor)
elif private:
self._tensor.index_add_(dim, index, tensor._tensor)
else:
raise TypeError("index_add second tensor of unsupported type")
return self
def scatter_add(self, dim, index, other):
"""Adds all values from the tensor other into self at the indices
specified in the index tensor.
"""
return self.clone().scatter_add_(dim, index, other)
def scatter_add_(self, dim, index, other):
"""Adds all values from the tensor other into self at the indices
specified in the index tensor."""
public = isinstance(other, (int, float)) or is_tensor(other)
private = isinstance(other, CrypTensor)
if public:
self._tensor.scatter_add_(dim, index, other)
elif private:
self._tensor.scatter_add_(dim, index, other._tensor)
else:
raise TypeError("scatter_add second tensor of unsupported type")
return self
def scatter_(self, dim, index, src):
"""Writes all values from the tensor `src` into `self` at the indices
specified in the `index` tensor. For each value in `src`, its output index
is specified by its index in `src` for `dimension != dim` and by the
corresponding value in `index` for `dimension = dim`.
"""
if is_tensor(src):
src = MPCTensor(src)
assert isinstance(
src, MPCTensor), "Unrecognized scatter src type: %s" % type(src)
self.share.scatter_(dim, index, src.share)
return self
def scatter(self, dim, index, src):
"""Out-of-place version of :meth:`MPCTensor.scatter_`"""
result = self.clone()
return result.scatter_(dim, index, src)
def unbind(self, dim=0):
shares = self.share.unbind(dim=dim)
results = tuple(
MPCTensor(0, ptype=self.ptype, device=self.device)
for _ in range(len(shares)))
for i in range(len(shares)):
results[i].share = shares[i]
return results
def split(self, split_size, dim=0):
shares = self.share.split(split_size, dim=dim)
results = tuple(
MPCTensor(0, ptype=self.ptype, device=self.device)
for _ in range(len(shares)))
for i in range(len(shares)):
results[i].share = shares[i]
return results
def set(self, enc_tensor):
"""
Sets self encrypted to enc_tensor in place by setting
shares of self to those of enc_tensor.
Args:
enc_tensor (MPCTensor): with encrypted shares.
"""
if is_tensor(enc_tensor):
enc_tensor = MPCTensor(enc_tensor)
assert isinstance(enc_tensor,
MPCTensor), "enc_tensor must be an MPCTensor"
self.share.set_(enc_tensor.share)
return self
class ArithmeticSharedTensor(object):
"""
Encrypted tensor object that uses additive sharing to perform computations.
Additive shares are computed by splitting each value of the input tensor
into n separate random values that add to the input tensor, where n is
the number of parties present in the protocol (world_size).
"""
# constructors:
def __init__(
self,
tensor=None,
size=None,
broadcast_size=False,
precision=None,
src=0,
device=None,
):
"""
Creates the shared tensor from the input `tensor` provided by party `src`.
The other parties can specify a `tensor` or `size` to determine the size
of the shared tensor object to create. In this case, all parties must
specify the same (tensor) size to prevent the party's shares from varying
in size, which leads to undefined behavior.
Alternatively, the parties can set `broadcast_size` to `True` to have the
`src` party broadcast the correct size. The parties who do not know the
tensor size beforehand can provide an empty tensor as input. This is
guaranteed to produce correct behavior but requires an additional
communication round.
The parties can also set the `precision` and `device` for their share of
the tensor. If `device` is unspecified, it is set to `tensor.device`.
"""
# do nothing if source is sentinel:
if src == SENTINEL:
return
# assertions on inputs:
assert (isinstance(src, int) and src >= 0
and src < comm.get().get_world_size()
), "specified source party does not exist"
if self.rank == src:
assert tensor is not None, "source must provide a data tensor"
if hasattr(tensor, "src"):
assert (
tensor.src == src
), "source of data tensor must match source of encryption"
if not broadcast_size:
assert (tensor is not None or size is not None
), "must specify tensor or size, or set broadcast_size"
# if device is unspecified, try and get it from tensor:
if device is None and tensor is not None and hasattr(tensor, "device"):
device = tensor.device
# encode the input tensor:
self.encoder = FixedPointEncoder(precision_bits=precision)
if tensor is not None:
if is_int_tensor(tensor) and precision != 0:
tensor = tensor.float()
tensor = self.encoder.encode(tensor)
tensor = tensor.to(device=device)
size = tensor.size()
# if other parties do not know tensor's size, broadcast the size:
if broadcast_size:
size = comm.get().broadcast_obj(size, src)
# generate pseudo-random zero sharing (PRZS) and add source's tensor:
self.share = ArithmeticSharedTensor.PRZS(size, device=device).share
if self.rank == src:
self.share += tensor
@staticmethod
def new(*args, **kwargs):
"""
Creates a new ArithmeticSharedTensor, passing all args and kwargs into the constructor.
"""
return ArithmeticSharedTensor(*args, **kwargs)
@property
def device(self):
"""Return the `torch.device` of the underlying _tensor"""
return self._tensor.device
@property
def is_cuda(self):
"""Return True if the underlying _tensor is stored on GPU, False otherwise"""
return self._tensor.is_cuda
def to(self, *args, **kwargs):
"""Call `torch.Tensor.to` on the underlying _tensor"""
self._tensor = self._tensor.to(*args, **kwargs)
return self
def cuda(self, *args, **kwargs):
"""Call `torch.Tensor.cuda` on the underlying _tensor"""
self._tensor = CUDALongTensor(self._tensor.cuda(*args, **kwargs))
return self
def cpu(self, *args, **kwargs):
"""Call `torch.Tensor.cpu` on the underlying _tensor"""
self._tensor = self._tensor.cpu(*args, **kwargs)
return self
@property
def share(self):
"""Returns underlying _tensor"""
return self._tensor
@share.setter
def share(self, value):
"""Sets _tensor to value"""
self._tensor = value
@staticmethod
def from_shares(share, precision=None, device=None):
"""Generate an ArithmeticSharedTensor from a share from each party"""
result = ArithmeticSharedTensor(src=SENTINEL)
share = share.to(device) if device is not None else share
result.share = CUDALongTensor(share) if share.is_cuda else share
result.encoder = FixedPointEncoder(precision_bits=precision)
return result
@staticmethod
def PRZS(*size, device=None):
"""
Generate a Pseudo-random Sharing of Zero (using arithmetic shares)
This function does so by generating `n` numbers across `n` parties with
each number being held by exactly 2 parties. One of these parties adds
this number while the other subtracts this number.
"""
from crypten import generators
tensor = ArithmeticSharedTensor(src=SENTINEL)
if device is None:
device = torch.device("cpu")
elif isinstance(device, str):
device = torch.device(device)
g0 = generators["prev"][device]
g1 = generators["next"][device]
current_share = generate_random_ring_element(*size,
generator=g0,
device=device)
next_share = generate_random_ring_element(*size,
generator=g1,
device=device)
tensor.share = current_share - next_share
return tensor
@staticmethod
def PRSS(*size, device=None):
"""
Generates a Pseudo-random Secret Share from a set of random arithmetic shares
"""
share = generate_random_ring_element(*size, device=device)
tensor = ArithmeticSharedTensor.from_shares(share=share)
return tensor
@property
def rank(self):
return comm.get().get_rank()
def shallow_copy(self):
"""Create a shallow copy"""
result = ArithmeticSharedTensor(src=SENTINEL)
result.encoder = self.encoder
result._tensor = self._tensor
return result
def clone(self):
result = ArithmeticSharedTensor(src=SENTINEL)
result.encoder = self.encoder
result._tensor = self._tensor.clone()
return result
def copy_(self, other):
"""Copies other tensor into this tensor."""
self.share.copy_(other.share)
self.encoder = other.encoder
def __repr__(self):
return f"ArithmeticSharedTensor({self.share})"
def __bool__(self):
"""Override bool operator since encrypted tensors cannot evaluate"""
raise RuntimeError(
"Cannot evaluate ArithmeticSharedTensors to boolean values")
def __nonzero__(self):
"""__bool__ for backwards compatibility with Python 2"""
raise RuntimeError(
"Cannot evaluate ArithmeticSharedTensors to boolean values")
def __setitem__(self, index, value):
"""Set tensor values by index"""
if isinstance(value, (int, float)) or is_tensor(value):
value = ArithmeticSharedTensor(value)
assert isinstance(
value, ArithmeticSharedTensor
), "Unsupported input type %s for __setitem__" % type(value)
self.share.__setitem__(index, value.share)
def pad(self, pad, mode="constant", value=0):
"""
Pads the input tensor with values provided in `value`.
"""
assert mode == "constant", (
"Padding with mode %s is currently unsupported" % mode)
result = self.shallow_copy()
if isinstance(value, (int, float)):
value = self.encoder.encode(value).item()
if result.rank == 0:
result.share = torch.nn.functional.pad(result.share,
pad,
mode=mode,
value=value)
else:
result.share = torch.nn.functional.pad(result.share,
pad,
mode=mode,
value=0)
elif isinstance(value, ArithmeticSharedTensor):
assert (value.dim() == 0
), "Private values used for padding must be 0-dimensional"
value = value.share.item()
result.share = torch.nn.functional.pad(result.share,
pad,
mode=mode,
value=value)
else:
raise TypeError(
"Cannot pad ArithmeticSharedTensor with a %s value" %
type(value))
return result
@staticmethod
def stack(tensors, *args, **kwargs):
"""Perform tensor stacking"""
for i, tensor in enumerate(tensors):
if is_tensor(tensor):
tensors[i] = ArithmeticSharedTensor(tensor)
assert isinstance(
tensors[i], ArithmeticSharedTensor
), "Can't stack %s with ArithmeticSharedTensor" % type(tensor)
result = tensors[0].shallow_copy()
result.share = torch_stack([tensor.share for tensor in tensors], *args,
**kwargs)
return result
@staticmethod
def reveal_batch(tensor_or_list, dst=None):
"""Get (batched) plaintext without any downscaling"""
if isinstance(tensor_or_list, ArithmeticSharedTensor):
return tensor_or_list.reveal(dst=dst)
assert isinstance(
tensor_or_list,
list), f"Invalid input type into reveal {type(tensor_or_list)}"
shares = [tensor.share for tensor in tensor_or_list]
if dst is None:
return comm.get().all_reduce(shares, batched=True)
else:
return comm.get().reduce(shares, dst, batched=True)
def reveal(self, dst=None):
"""Decrypts the tensor without any downscaling."""
tensor = self.share.clone()
if dst is None:
return comm.get().all_reduce(tensor)
else:
return comm.get().reduce(tensor, dst)
def get_plain_text(self, dst=None):
"""Decrypts the tensor."""
# Edge case where share becomes 0 sized (e.g. result of split)
if self.nelement() < 1:
return torch.empty(self.share.size())
return self.encoder.decode(self.reveal(dst=dst))
def encode_(self, new_encoder):
"""Rescales the input to a new encoding in-place"""
if self.encoder.scale == new_encoder.scale:
return self
elif self.encoder.scale < new_encoder.scale:
scale_factor = new_encoder.scale // self.encoder.scale
self.share *= scale_factor
else:
scale_factor = self.encoder.scale // new_encoder.scale
self = self.div_(scale_factor)
self.encoder = new_encoder
return self
def encode(self, new_encoder):
"""Rescales the input to a new encoding"""
return self.clone().encode_(new_encoder)
def encode_as_(self, other):
"""Rescales self to have the same encoding as other"""
return self.encode_(other.encoder)
def encode_as(self, other):
return self.encode(other.encoder)
def _arithmetic_function_(self, y, op, *args, **kwargs):
return self._arithmetic_function(y, op, inplace=True, *args, **kwargs)
def _arithmetic_function(self,
y,
op,
inplace=False,
*args,
**kwargs): # noqa:C901
assert op in [
"add",
"sub",
"mul",
"matmul",
"conv1d",
"conv2d",
"conv_transpose1d",
"conv_transpose2d",
], f"Provided op `{op}` is not a supported arithmetic function"
additive_func = op in ["add", "sub"]
public = isinstance(y, (int, float)) or is_tensor(y)
private = isinstance(y, ArithmeticSharedTensor)
if inplace:
result = self
if additive_func or (op == "mul" and public):
op += "_"
else:
result = self.clone()
if public:
y = result.encoder.encode(y, device=self.device)
if additive_func: # ['add', 'sub']
if result.rank == 0:
result.share = getattr(result.share, op)(y)
else:
result.share = torch.broadcast_tensors(result.share, y)[0]
elif op == "mul_": # ['mul_']
result.share = result.share.mul_(y)
else: # ['mul', 'matmul', 'convNd', 'conv_transposeNd']
result.share = getattr(torch, op)(result.share, y, *args,
**kwargs)
elif private:
if additive_func: # ['add', 'sub', 'add_', 'sub_']
# Re-encode if necessary:
if self.encoder.scale > y.encoder.scale:
y.encode_as_(result)
elif self.encoder.scale < y.encoder.scale:
result.encode_as_(y)
result.share = getattr(result.share, op)(y.share)
else: # ['mul', 'matmul', 'convNd', 'conv_transposeNd']
protocol = globals()[cfg.mpc.protocol]
result.share.set_(
getattr(protocol, op)(result, y, *args,
**kwargs).share.data)
else:
raise TypeError("Cannot %s %s with %s" % (op, type(y), type(self)))
# Scale by encoder scale if necessary
if not additive_func:
if public: # scale by self.encoder.scale
if self.encoder.scale > 1:
return result.div_(result.encoder.scale)
else:
result.encoder = self.encoder
else: # scale by larger of self.encoder.scale and y.encoder.scale
if self.encoder.scale > 1 and y.encoder.scale > 1:
return result.div_(result.encoder.scale)
elif self.encoder.scale > 1:
result.encoder = self.encoder
else:
result.encoder = y.encoder
return result
def add(self, y):
"""Perform element-wise addition"""
return self._arithmetic_function(y, "add")
def add_(self, y):
"""Perform element-wise addition"""
return self._arithmetic_function_(y, "add")
def sub(self, y):
"""Perform element-wise subtraction"""
return self._arithmetic_function(y, "sub")
def sub_(self, y):
"""Perform element-wise subtraction"""
return self._arithmetic_function_(y, "sub")
def mul(self, y):
"""Perform element-wise multiplication"""
if isinstance(y, int):
result = self.clone()
result.share = self.share * y
return result
return self._arithmetic_function(y, "mul")
def mul_(self, y):
"""Perform element-wise multiplication"""
if isinstance(y, int) or is_int_tensor(y):
self.share *= y
return self
return self._arithmetic_function_(y, "mul")
def div(self, y):
"""Divide by a given tensor"""
result = self.clone()
if isinstance(y, CrypTensor):
result.share = torch.broadcast_tensors(result.share,
y.share)[0].clone()
elif is_tensor(y):
result.share = torch.broadcast_tensors(result.share, y)[0].clone()
return result.div_(y)
def div_(self, y):
"""Divide two tensors element-wise"""
# TODO: Add test coverage for this code path (next 4 lines)
if isinstance(y, float) and int(y) == y:
y = int(y)
if is_float_tensor(y) and y.frac().eq(0).all():
y = y.long()
if isinstance(y, int) or is_int_tensor(y):
validate = cfg.debug.validation_mode
if validate:
tolerance = 1.0
tensor = self.get_plain_text()
# Truncate protocol for dividing by public integers:
if comm.get().get_world_size() > 2:
protocol = globals()[cfg.mpc.protocol]
protocol.truncate(self, y)
else:
self.share = self.share.div_(y, rounding_mode="trunc")
# Validate
if validate:
if not torch.lt(torch.abs(self.get_plain_text() * y - tensor),
tolerance).all():
raise ValueError("Final result of division is incorrect.")
return self
# Otherwise multiply by reciprocal
if isinstance(y, float):
y = torch.tensor([y], dtype=torch.float, device=self.device)
assert is_float_tensor(y), "Unsupported type for div_: %s" % type(y)
return self.mul_(y.reciprocal())
def matmul(self, y):
"""Perform matrix multiplication using some tensor"""
return self._arithmetic_function(y, "matmul")
def conv1d(self, kernel, **kwargs):
"""Perform a 1D convolution using the given kernel"""
return self._arithmetic_function(kernel, "conv1d", **kwargs)
def conv2d(self, kernel, **kwargs):
"""Perform a 2D convolution using the given kernel"""
return self._arithmetic_function(kernel, "conv2d", **kwargs)
def conv_transpose1d(self, kernel, **kwargs):
"""Perform a 1D transpose convolution (deconvolution) using the given kernel"""
return self._arithmetic_function(kernel, "conv_transpose1d", **kwargs)
def conv_transpose2d(self, kernel, **kwargs):
"""Perform a 2D transpose convolution (deconvolution) using the given kernel"""
return self._arithmetic_function(kernel, "conv_transpose2d", **kwargs)
def index_add(self, dim, index, tensor):
"""Perform out-of-place index_add: Accumulate the elements of tensor into the
self tensor by adding to the indices in the order given in index."""
result = self.clone()
return result.index_add_(dim, index, tensor)
def index_add_(self, dim, index, tensor):
"""Perform in-place index_add: Accumulate the elements of tensor into the
self tensor by adding to the indices in the order given in index."""
public = isinstance(tensor, (int, float)) or is_tensor(tensor)
private = isinstance(tensor, ArithmeticSharedTensor)
if public:
enc_tensor = self.encoder.encode(tensor)
if self.rank == 0:
self._tensor.index_add_(dim, index, enc_tensor)
elif private:
self._tensor.index_add_(dim, index, tensor._tensor)
else:
raise TypeError("index_add second tensor of unsupported type")
return self
def scatter_add(self, dim, index, other):
"""Adds all values from the tensor other into self at the indices
specified in the index tensor in a similar fashion as scatter_(). For
each value in other, it is added to an index in self which is specified
by its index in other for dimension != dim and by the corresponding
value in index for dimension = dim.
"""
return self.clone().scatter_add_(dim, index, other)
def scatter_add_(self, dim, index, other):
"""Adds all values from the tensor other into self at the indices
specified in the index tensor in a similar fashion as scatter_(). For
each value in other, it is added to an index in self which is specified
by its index in other for dimension != dim and by the corresponding
value in index for dimension = dim.
"""
public = isinstance(other, (int, float)) or is_tensor(other)
private = isinstance(other, ArithmeticSharedTensor)
if public:
if self.rank == 0:
self.share.scatter_add_(dim, index, self.encoder.encode(other))
elif private:
self.share.scatter_add_(dim, index, other.share)
else:
raise TypeError("scatter_add second tensor of unsupported type")
return self
def avg_pool2d(self, kernel_size, stride=None, padding=0, ceil_mode=False):
"""Perform an average pooling on each 2D matrix of the given tensor
Args:
kernel_size (int or tuple): pooling kernel size.
"""
# TODO: Add check for whether ceil_mode would change size of output and allow ceil_mode when it wouldn't
if ceil_mode:
raise NotImplementedError(
"CrypTen does not support `ceil_mode` for `avg_pool2d`")
z = self._sum_pool2d(kernel_size,
stride=stride,
padding=padding,
ceil_mode=ceil_mode)
if isinstance(kernel_size, (int, float)):
pool_size = kernel_size**2
else:
pool_size = kernel_size[0] * kernel_size[1]
return z / pool_size
def _sum_pool2d(self,
kernel_size,
stride=None,
padding=0,
ceil_mode=False):
"""Perform a sum pooling on each 2D matrix of the given tensor"""
result = self.shallow_copy()
result.share = torch.nn.functional.avg_pool2d(
self.share,
kernel_size,
stride=stride,
padding=padding,
ceil_mode=ceil_mode,
divisor_override=1,
)
return result
# negation and reciprocal:
def neg_(self):
"""Negate the tensor's values"""
self.share.neg_()
return self
def neg(self):
"""Negate the tensor's values"""
return self.clone().neg_()
def square_(self):
protocol = globals()[cfg.mpc.protocol]
self.share = protocol.square(self).div_(self.encoder.scale).share
return self
def square(self):
return self.clone().square_()
def where(self, condition, y):
"""Selects elements from self or y based on condition
Args:
condition (torch.bool or ArithmeticSharedTensor): when True
yield self, otherwise yield y.
y (torch.tensor or ArithmeticSharedTensor): values selected at
indices where condition is False.
Returns: ArithmeticSharedTensor or torch.tensor
"""
if is_tensor(condition):
condition = condition.float()
y_masked = y * (1 - condition)
else:
# encrypted tensor must be first operand
y_masked = (1 - condition) * y
return self * condition + y_masked
def scatter_(self, dim, index, src):
"""Writes all values from the tensor `src` into `self` at the indices
specified in the `index` tensor. For each value in `src`, its output index
is specified by its index in `src` for `dimension != dim` and by the
corresponding value in `index` for `dimension = dim`.
"""
if is_tensor(src):
src = ArithmeticSharedTensor(src)
assert isinstance(src, ArithmeticSharedTensor
), "Unrecognized scatter src type: %s" % type(src)
self.share.scatter_(dim, index, src.share)
return self
def scatter(self, dim, index, src):
"""Writes all values from the tensor `src` into `self` at the indices
specified in the `index` tensor. For each value in `src`, its output index
is specified by its index in `src` for `dimension != dim` and by the
corresponding value in `index` for `dimension = dim`.
"""
result = self.clone()
return result.scatter_(dim, index, src)
# overload operators:
__add__ = add
__iadd__ = add_
__radd__ = __add__
__sub__ = sub
__isub__ = sub_
__mul__ = mul
__imul__ = mul_
__rmul__ = __mul__
__div__ = div
__truediv__ = div
__itruediv__ = div_
__neg__ = neg
def __rsub__(self, tensor):
"""Subtracts self from tensor."""
return -self + tensor
@property
def data(self):
return self._tensor.data
@data.setter
def data(self, value):
self._tensor.set_(value)
class MPCTensor(CrypTensor):
def __init__(self,
tensor,
ptype=Ptype.arithmetic,
device=None,
*args,
**kwargs):
"""
Creates the shared tensor from the input `tensor` provided by party `src`.
The `ptype` defines the type of sharing used (default: arithmetic).
The other parties can specify a `tensor` or `size` to determine the size
of the shared tensor object to create. In this case, all parties must
specify the same (tensor) size to prevent the party's shares from varying
in size, which leads to undefined behavior.
Alternatively, the parties can set `broadcast_size` to `True` to have the
`src` party broadcast the correct size. The parties who do not know the
tensor size beforehand can provide an empty tensor as input. This is
guaranteed to produce correct behavior but requires an additional
communication round.
The parties can also set the `precision` and `device` for their share of
the tensor. If `device` is unspecified, it is set to `tensor.device`.
"""
if tensor is None:
raise ValueError("Cannot initialize tensor with None.")
# take required_grad from kwargs, input tensor, or set to False:
default = tensor.requires_grad if torch.is_tensor(tensor) else False
requires_grad = kwargs.pop("requires_grad", default)
# call CrypTensor constructor:
super().__init__(requires_grad=requires_grad)
if device is None and hasattr(tensor, "device"):
device = tensor.device
# create the MPCTensor:
tensor_type = ptype.to_tensor()
if tensor is []:
self._tensor = torch.tensor([], device=device)
else:
self._tensor = tensor_type(tensor=tensor,
device=device,
*args,
**kwargs)
self.ptype = ptype
@staticmethod
def new(*args, **kwargs):
"""
Creates a new MPCTensor, passing all args and kwargs into the constructor.
"""
return MPCTensor(*args, **kwargs)
@staticmethod
def from_shares(share, precision=None, ptype=Ptype.arithmetic):
result = MPCTensor([])
from_shares = ptype.to_tensor().from_shares
result._tensor = from_shares(share, precision=precision)
result.ptype = ptype
return result
def clone(self):
"""Create a deep copy of the input tensor."""
# TODO: Rename this to __deepcopy__()?
result = MPCTensor([])
result._tensor = self._tensor.clone()
result.ptype = self.ptype
return result
def shallow_copy(self):
"""Create a shallow copy of the input tensor."""
# TODO: Rename this to __copy__()?
result = MPCTensor([])
result._tensor = self._tensor
result.ptype = self.ptype
return result
def copy_(self, other):
"""Copies value of other MPCTensor into this MPCTensor."""
assert isinstance(other, MPCTensor), "other must be MPCTensor"
self._tensor.copy_(other._tensor)
self.ptype = other.ptype
def to(self, *args, **kwargs):
r"""
Depending on the input arguments,
converts underlying share to the given ptype or
performs `torch.to` on the underlying torch tensor
To convert underlying share to the given ptype, call `to` as:
to(ptype, **kwargs)
It will call MPCTensor.to_ptype with the arguments provided above.
Otherwise, `to` performs `torch.to` on the underlying
torch tensor. See
https://pytorch.org/docs/stable/tensors.html?highlight=#torch.Tensor.to
for a reference of the parameters that can be passed in.
Args:
ptype: Ptype.arithmetic or Ptype.binary.
"""
if "ptype" in kwargs:
return self._to_ptype(**kwargs)
elif args and isinstance(args[0], Ptype):
ptype = args[0]
return self._to_ptype(ptype, **kwargs)
else:
share = self.share.to(*args, **kwargs)
if share.is_cuda:
share = CUDALongTensor(share)
self.share = share
return self
def _to_ptype(self, ptype, **kwargs):
r"""
Convert MPCTensor's underlying share to the corresponding ptype
(ArithmeticSharedTensor, BinarySharedTensor)
Args:
ptype (Ptype.arithmetic or Ptype.binary): The ptype to convert
the shares to.
precision (int, optional): Precision of the fixed point encoder when
converting a binary share to an arithmetic share. It will be ignored
if the ptype doesn't match.
bits (int, optional): If specified, will only preserve the bottom `bits` bits
of a binary tensor when converting from a binary share to an arithmetic share.
It will be ignored if the ptype doesn't match.
"""
retval = self.clone()
if retval.ptype == ptype:
return retval
retval._tensor = convert(self._tensor, ptype, **kwargs)
retval.ptype = ptype
return retval
def arithmetic(self):
"""Converts self._tensor to arithmetic secret sharing"""
return self.to(Ptype.arithmetic)
def binary(self):
"""Converts self._tensor to binary secret sharing"""
return self.to(Ptype.binary)
@property
def device(self):
"""Return the `torch.device` of the underlying share"""
return self.share.device
@property
def is_cuda(self):
"""Return True if the underlying share is stored on GPU, False otherwise"""
return self.share.is_cuda
def cuda(self, *args, **kwargs):
"""Call `torch.Tensor.cuda` on the underlying share"""
self.share = CUDALongTensor(self.share.cuda(*args, **kwargs))
return self
def cpu(self):
"""Call `torch.Tensor.cpu` on the underlying share"""
self.share = self.share.cpu()
return self
def get_plain_text(self, dst=None):
"""Decrypts the tensor."""
return self._tensor.get_plain_text(dst=dst)
def reveal(self, dst=None):
"""Decrypts the tensor without any downscaling."""
return self._tensor.reveal(dst=dst)
def __repr__(self):
"""Returns a representation of the tensor useful for debugging."""
from crypten.debug import debug_mode
share = self.share
plain_text = self._tensor.get_plain_text() if debug_mode(
) else "HIDDEN"
ptype = self.ptype
return (f"MPCTensor(\n\t_tensor={share}\n"
f"\tplain_text={plain_text}\n\tptype={ptype}\n)")
def __hash__(self):
return hash(self.share)
@property
def share(self):
"""Returns underlying share"""
return self._tensor.share
@share.setter
def share(self, value):
"""Sets share to value"""
self._tensor.share = value
@property
def data(self):
"""Returns share data"""
return self.share.data
@data.setter
def data(self, value):
"""Sets data to value"""
self.share.data = value
@property
def encoder(self):
"""Returns underlying encoder"""
return self._tensor.encoder
@encoder.setter
def encoder(self, value):
"""Sets encoder to value"""
self._tensor.encoder = value
@staticmethod
def __cat_stack_helper(op, tensors, *args, **kwargs):
assert op in ["cat", "stack"], "Unsupported op for helper function"
assert isinstance(tensors, list), "%s input must be a list" % op
assert len(tensors) > 0, "expected a non-empty list of MPCTensors"
_ptype = kwargs.pop("ptype", None)
# Populate ptype field
if _ptype is None:
for tensor in tensors:
if isinstance(tensor, MPCTensor):
_ptype = tensor.ptype
break
if _ptype is None:
_ptype = Ptype.arithmetic
# Make all inputs MPCTensors of given ptype
for i, tensor in enumerate(tensors):
if tensor.ptype != _ptype:
tensors[i] = tensor.to(_ptype)
# Operate on all input tensors
result = tensors[0].clone()
funcs = {"cat": torch_cat, "stack": torch_stack}
result.share = funcs[op]([tensor.share for tensor in tensors], *args,
**kwargs)
return result
@staticmethod
def cat(tensors, *args, **kwargs):
"""Perform matrix concatenation"""
return MPCTensor.__cat_stack_helper("cat", tensors, *args, **kwargs)
@staticmethod
def stack(tensors, *args, **kwargs):
"""Perform tensor stacking"""
return MPCTensor.__cat_stack_helper("stack", tensors, *args, **kwargs)
@staticmethod
def rand(*sizes, device=None):
"""
Returns a tensor with elements uniformly sampled in [0, 1). The uniform
random samples are generated by generating random bits using fixed-point
encoding and converting the result to an ArithmeticSharedTensor.
"""
rand = MPCTensor([])
encoder = FixedPointEncoder()
rand._tensor = BinarySharedTensor.rand(*sizes,
bits=encoder._precision_bits,
device=device)
rand._tensor.encoder = encoder
rand.ptype = Ptype.binary
return rand.to(Ptype.arithmetic, bits=encoder._precision_bits)
@staticmethod
def randn(*sizes, device=None):
"""
Returns a tensor with normally distributed elements. Samples are
generated using the Box-Muller transform with optimizations for
numerical precision and MPC efficiency.
"""
u = MPCTensor.rand(*sizes, device=device).flatten()
odd_numel = u.numel() % 2 == 1
if odd_numel:
u = MPCTensor.cat([u, MPCTensor.rand((1, ), device=device)])
n = u.numel() // 2
u1 = u[:n]
u2 = u[n:]
# Radius = sqrt(- 2 * log(u1))
r2 = -2 * u1.log(input_in_01=True)
r = r2.sqrt()
# Theta = cos(2 * pi * u2) or sin(2 * pi * u2)
cos, sin = u2.sub(0.5).mul(6.28318531).cossin()
# Generating 2 independent normal random variables using
x = r.mul(sin)
y = r.mul(cos)
z = MPCTensor.cat([x, y])
if odd_numel:
z = z[1:]
return z.view(*sizes)
def bernoulli(self):
"""Returns a tensor with elements in {0, 1}. The i-th element of the
output will be 1 with probability according to the i-th value of the
input tensor."""
return self > MPCTensor.rand(self.size(), device=self.device)
# Comparators
@mode(Ptype.binary)
def _ltz(self, _scale=True):
"""Returns 1 for elements that are < 0 and 0 otherwise"""
shift = torch.iinfo(torch.long).bits - 1
result = (self >> shift).to(Ptype.arithmetic, bits=1)
if _scale:
return result * result.encoder._scale
else:
result.encoder._scale = 1
return result
@mode(Ptype.arithmetic)
def ge(self, y, _scale=True):
"""Returns self >= y"""
return 1 - self.lt(y, _scale=_scale)
@mode(Ptype.arithmetic)
def gt(self, y, _scale=True):
"""Returns self > y"""
return (-self + y)._ltz(_scale=_scale)
@mode(Ptype.arithmetic)
def le(self, y, _scale=True):
"""Returns self <= y"""
return 1 - self.gt(y, _scale=_scale)
@mode(Ptype.arithmetic)
def lt(self, y, _scale=True):
"""Returns self < y"""
return (self - y)._ltz(_scale=_scale)
@mode(Ptype.arithmetic)
def eq(self, y, _scale=True):
"""Returns self == y"""
if comm.get().get_world_size() == 2:
return (self - y)._eqz_2PC(_scale=_scale)
return 1 - self.ne(y, _scale=_scale)
@mode(Ptype.arithmetic)
def ne(self, y, _scale=True):
"""Returns self != y"""
if comm.get().get_world_size() == 2:
return 1 - self.eq(y, _scale=_scale)
difference = self - y
difference.share = torch_stack([difference.share, -(difference.share)])
return difference._ltz(_scale=_scale).sum(0)
@mode(Ptype.arithmetic)
def _eqz_2PC(self, _scale=True):
"""Returns self == 0"""
# Create BinarySharedTensors from shares
x0 = MPCTensor(self.share, src=0, ptype=Ptype.binary)
x1 = MPCTensor(-self.share, src=1, ptype=Ptype.binary)
# Perform equality testing using binary shares
x0._tensor = x0._tensor.eq(x1._tensor)
x0.encoder = x0.encoder if _scale else self.encoder
# Convert to Arithmetic sharing
result = x0.to(Ptype.arithmetic, bits=1)
if not _scale:
result.encoder._scale = 1
return result
@mode(Ptype.arithmetic)
def sign(self, _scale=True):
"""Computes the sign value of a tensor (0 is considered positive)"""
return 1 - 2 * self._ltz(_scale=_scale)
@mode(Ptype.arithmetic)
def abs(self):
"""Computes the absolute value of a tensor"""
return self * self.sign(_scale=False)
@mode(Ptype.arithmetic)
def relu(self):
"""Compute a Rectified Linear function on the input tensor."""
return self * self.ge(0, _scale=False)
@mode(Ptype.arithmetic)
def weighted_index(self, dim=None):
"""
Returns a tensor with entries that are one-hot along dimension `dim`.
These one-hot entries are set at random with weights given by the input
`self`.
Examples::
>>> encrypted_tensor = MPCTensor(torch.tensor([1., 6.]))
>>> index = encrypted_tensor.weighted_index().get_plain_text()
# With 1 / 7 probability
torch.tensor([1., 0.])
# With 6 / 7 probability
torch.tensor([0., 1.])
"""
if dim is None:
return self.flatten().weighted_index(dim=0).view(self.size())
x = self.cumsum(dim)
max_weight = x.index_select(
dim, torch.tensor(x.size(dim) - 1, device=self.device))
r = MPCTensor.rand(max_weight.size(), device=self.device) * max_weight
gt = x.gt(r, _scale=False)
shifted = gt.roll(1, dims=dim)
shifted.share.index_fill_(dim, torch.tensor(0, device=self.device), 0)
return gt - shifted
@mode(Ptype.arithmetic)
def weighted_sample(self, dim=None):
"""
Samples a single value across dimension `dim` with weights corresponding
to the values in `self`
Returns the sample and the one-hot index of the sample.
Examples::
>>> encrypted_tensor = MPCTensor(torch.tensor([1., 6.]))
>>> index = encrypted_tensor.weighted_sample().get_plain_text()
# With 1 / 7 probability
(torch.tensor([1., 0.]), torch.tensor([1., 0.]))
# With 6 / 7 probability
(torch.tensor([0., 6.]), torch.tensor([0., 1.]))
"""
indices = self.weighted_index(dim)
sample = self.mul(indices).sum(dim)
return sample, indices
# max / min-related functions
@mode(Ptype.arithmetic)
def argmax(self, dim=None, keepdim=False, one_hot=True):
"""Returns the indices of the maximum value of all elements in the
`input` tensor.
"""
# TODO: Make dim an arg.
if self.dim() == 0:
result = (MPCTensor(torch.ones(
(), device=self.device)) if one_hot else MPCTensor(
torch.zeros((), device=self.device)))
return result
result = _argmax_helper(self,
dim,
one_hot,
config.max_method,
_return_max=False)
if not one_hot:
result = _one_hot_to_index(result, dim, keepdim, self.device)
return result
@mode(Ptype.arithmetic)
def argmin(self, dim=None, keepdim=False, one_hot=True):
"""Returns the indices of the minimum value of all elements in the
`input` tensor.
"""
# TODO: Make dim an arg.
return (-self).argmax(dim=dim, keepdim=keepdim, one_hot=one_hot)
@mode(Ptype.arithmetic)
def max(self, dim=None, keepdim=False, one_hot=True):
"""Returns the maximum value of all elements in the input tensor."""
# TODO: Make dim an arg.
method = config.max_method
if dim is None:
if method in ["log_reduction", "double_log_reduction"]:
# max_result can be obtained directly
max_result = _max_helper_all_tree_reductions(self,
method=method)
else:
# max_result needs to be obtained through argmax
with ConfigManager("max_method", method):
argmax_result = self.argmax(one_hot=True)
max_result = self.mul(argmax_result).sum()
return max_result
else:
argmax_result, max_result = _argmax_helper(self,
dim=dim,
one_hot=True,
method=method,
_return_max=True)
if max_result is None:
max_result = (self * argmax_result).sum(dim=dim,
keepdim=keepdim)
if keepdim:
max_result = (max_result.unsqueeze(dim)
if max_result.dim() < self.dim() else max_result)
if one_hot:
return max_result, argmax_result
else:
return (
max_result,
_one_hot_to_index(argmax_result, dim, keepdim,
self.device),
)
@mode(Ptype.arithmetic)
def min(self, dim=None, keepdim=False, one_hot=True):
"""Returns the minimum value of all elements in the input tensor."""
# TODO: Make dim an arg.
result = (-self).max(dim=dim, keepdim=keepdim, one_hot=one_hot)
if dim is None:
return -result
else:
return -result[0], result[1]
@mode(Ptype.arithmetic)
def max_pool2d(
self,
kernel_size,
padding=0,
stride=None,
dilation=1,
ceil_mode=False,
return_indices=False,
):
"""Applies a 2D max pooling over an input signal composed of several
input planes.
"""
max_input = self.shallow_copy()
max_input.share, output_size = pool2d_reshape(
self.share,
kernel_size,
padding=padding,
stride=stride,
dilation=dilation,
ceil_mode=ceil_mode,
# padding with extremely negative values to avoid choosing pads.
# The magnitude of this value should not be too large because
# multiplication can otherwise fail.
pad_value=(-(2**24)),
# TODO: Find a better solution for padding with max_pooling
)
max_vals, argmax_vals = max_input.max(dim=-1, one_hot=True)
max_vals = max_vals.view(output_size)
if return_indices:
if isinstance(kernel_size, int):
kernel_size = (kernel_size, kernel_size)
argmax_vals = argmax_vals.view(output_size + kernel_size)
return max_vals, argmax_vals
return max_vals
@mode(Ptype.arithmetic)
def _max_pool2d_backward(
self,
indices,
kernel_size,
padding=None,
stride=None,
dilation=1,
ceil_mode=False,
output_size=None,
):
"""Implements the backwards for a `max_pool2d` call."""
# Setup padding
if padding is None:
padding = 0
if isinstance(padding, int):
padding = padding, padding
assert isinstance(padding,
tuple), "padding must be a int, tuple, or None"
p0, p1 = padding
# Setup stride
if stride is None:
stride = kernel_size
if isinstance(stride, int):
stride = stride, stride
assert isinstance(stride,
tuple), "stride must be a int, tuple, or None"
s0, s1 = stride
# Setup dilation
if isinstance(stride, int):
dilation = dilation, dilation
assert isinstance(dilation,
tuple), "dilation must be a int, tuple, or None"
d0, d1 = dilation
# Setup kernel_size
if isinstance(kernel_size, int):
kernel_size = kernel_size, kernel_size
assert isinstance(padding, tuple), "padding must be a int or tuple"
k0, k1 = kernel_size
assert self.dim(
) == 4, "Input to _max_pool2d_backward must have 4 dimensions"
assert (
indices.dim() == 6
), "Indices input for _max_pool2d_backward must have 6 dimensions"
# Computes one-hot gradient blocks from each output variable that
# has non-zero value corresponding to the argmax of the corresponding
# block of the max_pool2d input.
kernels = self.view(self.size() + (1, 1)) * indices
# Use minimal size if output_size is not specified.
if output_size is None:
output_size = (
self.size(0),
self.size(1),
s0 * self.size(2) - 2 * p0,
s1 * self.size(3) - 2 * p1,
)
# Account for input padding
result_size = list(output_size)
result_size[-2] += 2 * p0
result_size[-1] += 2 * p1
# Account for input padding implied by ceil_mode
if ceil_mode:
c0 = self.size(-1) * s1 + (k1 - 1) * d1 - output_size[-1]
c1 = self.size(-2) * s0 + (k0 - 1) * d0 - output_size[-2]
result_size[-2] += c0
result_size[-1] += c1
# Sum the one-hot gradient blocks at corresponding index locations.
result = MPCTensor(torch.zeros(result_size, device=kernels.device))
for i in range(self.size(2)):
for j in range(self.size(3)):
left_ind = s0 * i
top_ind = s1 * j
result[:, :, left_ind:left_ind + k0 * d0:d0,
top_ind:top_ind + k1 * d1:d1, ] += kernels[:, :, i, j]
# Remove input padding
if ceil_mode:
result = result[:, :, :result.size(2) - c0, :result.size(3) - c1]
result = result[:, :, p0:result.size(2) - p0, p1:result.size(3) - p1]
return result
def adaptive_avg_pool2d(self, output_size):
r"""
Applies a 2D adaptive average pooling over an input signal composed of
several input planes.
See :class:`~torch.nn.AdaptiveAvgPool2d` for details and output shape.
Args:
output_size: the target output size (single integer or
double-integer tuple)
"""
resized_input, args, kwargs = adaptive_pool2d_helper(self,
output_size,
reduction="mean")
return resized_input.avg_pool2d(*args, **kwargs)
def adaptive_max_pool2d(self, output_size, return_indices=False):
r"""Applies a 2D adaptive max pooling over an input signal composed of
several input planes.
See :class:`~torch.nn.AdaptiveMaxPool2d` for details and output shape.
Args:
output_size: the target output size (single integer or
double-integer tuple)
return_indices: whether to return pooling indices. Default: ``False``
"""
resized_input, args, kwargs = adaptive_pool2d_helper(self,
output_size,
reduction="max")
return resized_input.max_pool2d(*args,
**kwargs,
return_indices=return_indices)
def where(self, condition, y):
"""Selects elements from self or y based on condition
Args:
condition (torch.bool or MPCTensor): when True yield self,
otherwise yield y
y (torch.tensor or MPCTensor): values selected at indices
where condition is False.
Returns: MPCTensor or torch.tensor
"""
if is_tensor(condition):
condition = condition.float()
y_masked = y * (1 - condition)
else:
# encrypted tensor must be first operand
y_masked = (1 - condition) * y
return self * condition + y_masked
@mode(Ptype.arithmetic)
def div(self, y):
r"""Divides each element of :attr:`self` with the scalar :attr:`y` or
each element of the tensor :attr:`y` and returns a new resulting tensor.
For `y` a scalar:
.. math::
\text{out}_i = \frac{\text{self}_i}{\text{y}}
For `y` a tensor:
.. math::
\text{out}_i = \frac{\text{self}_i}{\text{y}_i}
Note for :attr:`y` a tensor, the shapes of :attr:`self` and :attr:`y` must be
`broadcastable`_.
.. _broadcastable:
https://pytorch.org/docs/stable/notes/broadcasting.html#broadcasting-semantics""" # noqa: B950
result = self.clone()
if isinstance(y, CrypTensor):
result.share = torch.broadcast_tensors(result.share,
y.share)[0].clone()
elif is_tensor(y):
result.share = torch.broadcast_tensors(result.share, y)[0].clone()
if isinstance(y, MPCTensor):
return result.mul(y.reciprocal())
result._tensor.div_(y)
return result
def div_(self, y):
"""In-place version of :meth:`div`"""
if isinstance(y, MPCTensor):
return self.mul_(y.reciprocal())
self._tensor.div_(y)
return self
def index_add(self, dim, index, tensor):
"""Performs out-of-place index_add: Accumulate the elements of tensor into the
self tensor by adding to the indices in the order given in index.
"""
result = self.clone()
assert index.dim() == 1, "index needs to be a vector"
public = isinstance(tensor, (int, float)) or is_tensor(tensor)
private = isinstance(tensor, MPCTensor)
if public:
result._tensor.index_add_(dim, index, tensor)
elif private:
result._tensor.index_add_(dim, index, tensor._tensor)
else:
raise TypeError("index_add second tensor of unsupported type")
return result
def scatter_add(self, dim, index, other):
"""Adds all values from the tensor other into self at the indices
specified in the index tensor.
"""
result = self.clone()
public = isinstance(other, (int, float)) or is_tensor(other)
private = isinstance(other, CrypTensor)
if public:
result._tensor.scatter_add_(dim, index, other)
elif private:
result._tensor.scatter_add_(dim, index, other._tensor)
else:
raise TypeError("scatter_add second tensor of unsupported type")
return result
def scatter(self, dim, index, src):
"""Out-of-place version of :meth:`MPCTensor.scatter_`"""
result = self.clone()
if is_tensor(src):
src = MPCTensor(src)
assert isinstance(
src, MPCTensor), "Unrecognized scatter src type: %s" % type(src)
result.share.scatter_(dim, index, src.share)
return result
def unbind(self, dim=0):
shares = self.share.unbind(dim=dim)
results = tuple(
MPCTensor(0, ptype=self.ptype, device=self.device)
for _ in range(len(shares)))
for i in range(len(shares)):
results[i].share = shares[i]
return results
def split(self, split_size, dim=0):
shares = self.share.split(split_size, dim=dim)
results = tuple(
MPCTensor(0, ptype=self.ptype, device=self.device)
for _ in range(len(shares)))
for i in range(len(shares)):
results[i].share = shares[i]
return results
def set(self, enc_tensor):
"""
Sets self encrypted to enc_tensor in place by setting
shares of self to those of enc_tensor.
Args:
enc_tensor (MPCTensor): with encrypted shares.
"""
if is_tensor(enc_tensor):
enc_tensor = MPCTensor(enc_tensor)
assert isinstance(enc_tensor,
MPCTensor), "enc_tensor must be an MPCTensor"
self.share.set_(enc_tensor.share)
return self