Addax: A fast, private, and accountable ad exchange infrastructure


Ke Zhong, Yiping Ma, and Yifeng Mao, University of Pennsylvania; Sebastian Angel, University of Pennsylvania & Microsoft Research


This paper proposes Addax, a fast, verifiable, and private online ad exchange. When a user visits an ad-supported site, Addax runs an auction similar to those of leading exchanges; Addax requests bids, selects the winner, collects payment, and displays the ad to the user. A key distinction is that bids in Addax's auctions are kept private and the outcome of the auction is publicly verifiable. Addax achieves these properties by adding public verifiability to the affine aggregatable encodings in Prio (NSDI'17) and by building an auction protocol out of them. Our implementation of Addax over WAN with hundreds of bidders can run roughly half the auctions per second as a non-private and non-verifiable exchange, while delivering ads to users in under 600 ms with little additional bandwidth requirements. This efficiency makes Addax the first architecture capable of bringing transparency to this otherwise opaque ecosystem.

NSDI '23 Open Access Sponsored by
King Abdullah University of Science and Technology (KAUST)

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This content is available to:

@inproceedings {285151,
author = {Ke Zhong and Yiping Ma and Yifeng Mao and Sebastian Angel},
title = {Addax: A fast, private, and accountable ad exchange infrastructure},
booktitle = {20th USENIX Symposium on Networked Systems Design and Implementation (NSDI 23)},
year = {2023},
isbn = {978-1-939133-33-5},
address = {Boston, MA},
pages = {825--848},
url = {},
publisher = {USENIX Association},
month = apr
Zhong Paper (Prepublication) PDF

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