S2025:E04
OSPEAD estimates the age distribution of the real spend in Monero’s ring signatures. Monero’s decoy selection algorithm could be changed to closely mimic the real spend age distribution, yet an anti-privacy adversary can also use the real spend distribution to execute the MAP Decoder attack on past ring signature data. The attack raises the probability of correctly guessing the real spend in a 16-member ring from 6.25% to 23.5%, on average.
Multiple nonstandard decoy distributions are modeled as repeated measurements drawn from unknown distributions components, then estimated by the method of Bonhomme, Jochmans, & Robin (2016). The age distribution of ring signatures associated with a given decoy distribution is modeled as a two-component mixture distribution. The decoy distribution is subtracted from the on-chain data distribution to obtain the real spend distribution.
