Gradient Compression for Privacy

Gradient Compression for Privacy is the use of gradient compression techniques (sparsification, quantization) to reduce privacy leakage in distributed training — by transmitting only partial gradient information, less private data can be reconstructed from the shared updates.

Compression as Privacy Mechanism

• Top-K Sparsification: Send only the K largest gradient components — attackers cannot reconstruct full gradient.
• Random Sparsification: Randomly sample gradient components to share — adds uncertainty for attackers.
• Quantization: Reduce gradient precision (e.g., 1-bit SGD) — less information per component.
• Combined: Use compression with DP noise for amplified privacy (privacy amplification by subsampling).

Why It Matters

• Dual Benefit: Gradient compression reduces both communication cost AND privacy leakage.
• Gradient Inversion: Full-precision gradients can be inverted to reconstruct training data — compression makes inversion harder.
• Practical: Compression is already used for efficiency in distributed training — the privacy benefit comes for free.

Gradient Compression for Privacy is leaking less by sending less — using gradient compression to simultaneously improve communication efficiency and data privacy.