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Support duplicates in PathObliviousHeap

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This commit is contained in:
Thomas Skovlund Hansen
2023-05-06 17:26:20 +02:00
parent 46ccaebba0
commit bf48400287
1 changed files with 10 additions and 6 deletions
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16
Compiler/path_oblivious_heap.py
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@@ -605,6 +605,9 @@ class BasicMinTree(NoIndexORAM):
if DEBUG:
dprint_ln("[POH] extract_min: searching path to leaf %s", leaf_label)
# If duplicates, ensure we only remove one.
done = MemValue(sint(0))
# Scan path and remove element (unless fake)
for i, _, _ in self._get_reversed_min_indices_and_children_on_path_to(
leaf_label
@@ -619,7 +622,8 @@ class BasicMinTree(NoIndexORAM):
dprint_str("[POH] extract_min: current element (bucket %s): ", i)
current_entry.dump(indent=False)
found = min_entry == current_entry
current_entry.write_if((1 - fake) * found, empty_entry)
done.write(found.max(done.read()))
current_entry.write_if((1 - fake) * found * (1 - done), empty_entry)
self.buckets[j] = current_entry.to_entry()
# Scan stash and remove element (unless fake)
@@ -629,7 +633,8 @@ class BasicMinTree(NoIndexORAM):
if TRACE:
current_entry.dump(f"[POH] extract_min: current element (stash): ")
found = min_entry == current_entry
current_entry.write_if((1 - fake) * found, empty_entry)
done.write(found.max(done.read()))
current_entry.write_if((1 - fake) * found * (1 - done), empty_entry)
self.stash.ram[i] = current_entry.to_entry()
# evict along path to leaf
@@ -832,10 +837,7 @@ class PathObliviousHeap(AbstractMinPriorityQueue[_secret]):
If the flag is set, the program crashes. Otherwise, the entry is simply
not inserted.
The queue does not support duplicates; extract_min removes all entries
that are equal to the global min entry on the traversed path.
:ivar capacity: The max capacity of the queue.
:ivar capacity: The capacity of the queue.
:ivar type_hiding_security: A boolean indicating whether
type hiding security is enabled. Enabling this
makes the cost of every operation equal to the
@@ -1066,6 +1068,7 @@ class UniquePathObliviousHeap(PathObliviousHeap):
def insert(self, value, priority, fake: bool = False) -> None:
self.update(value, priority, fake=fake)
class POHToHeapQAdapter(PathObliviousHeap):
"""
Adapts Path Oblivious Heap to the HeapQ interface,
@@ -1109,6 +1112,7 @@ class POHToHeapQAdapter(PathObliviousHeap):
"""Renaming of pop to extract_min."""
return self.extract_min(fake=(1 - for_real))
class UniquePOHToHeapQAdapter(UniquePathObliviousHeap):
"""
Adapts Unique Path Oblivious Heap to the HeapQ interface,