Fix Gaussian sensitivity for replace-one adjacency - #464
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kernelpanic888 wants to merge 1 commit into
Open
kernelpanic888 wants to merge 1 commit into
kernelpanic888 wants to merge 1 commit into
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Account for the 2C sensitivity of clipped sums under replace-one adjacency and add regression coverage for direct and fully sampled Gaussian events.
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Summary
Why
GaussianDpEventdefines its noise multiplier ass / C, whereCis the per-record norm bound. Under replace-one adjacency, two clipped records may differ by2C, so formulas normalized by L2 sensitivity must receive half that multiplier. Without this adjustment, RDP can be underestimated by a factor of four.Fixes #378.
Tests
python3 -m pytest python/dp_accounting/dp_accounting/rdp/rdp_privacy_accountant_test.py -q(160 passed)