def test_torch_unbind(self):
"""Test torch.unbind on CUDALongTensor"""
sizes = [
(1,),
(5,),
(1, 1),
(1, 5),
(5, 5),
(1, 1, 1),
(5, 5, 5),
(1, 1, 1, 1),
(5, 5, 5, 5),
]
for size in sizes:
tensor = get_random_test_tensor(size=size, is_float=False)
t_cuda = CUDALongTensor(tensor)
for dim in range(tensor.dim()):
reference = tensor.unbind(dim)
result = torch.unbind(t_cuda, dim)
result2 = t_cuda.unbind(dim)
for i in range(len(result)):
self.assertTrue(
type(result[i]) == CUDALongTensor,
"result should be a CUDALongTensor",
)
self.assertTrue(
type(result2[i]) == CUDALongTensor,
"result should be a CUDALongTensor",
)
self._check_int(
result[i].cpu(), reference[i], "unbind failed on CUDALongTensor"
)
self._check_int(
result2[i].cpu(),
reference[i],
"unbind failed on CUDALongTensor",
)
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 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