burdges
commented
7 years ago Attack paper :
https://eprint.iacr.org/2016/729.pdf
Chaum et al. have very recently introduced cMix as the first practical system that offers senders-receivers unlinkability at scale. cMix is claimed by its authors to be secure unless all nodes collude (or less than two senders are honest). We argue their assertion does not hold and sustain our statement by three different types of attacks: tagging attack, insider attack and passive attack. For each one, we discuss the settings that make it feasible and possible countermeasures.
https://eprint.iacr.org/2016/008.pdf
cMix is the first practical system that can prevent traffic analysis of chat messages at scale. It creates a complete anonymity set every second for all messages sent during the previous second. cMix uniquely requires no public-key operations during the sending of a chat message—neither by the smart phone sending the message, the roughly ten nodes that process each message in sequence, nor the receiving smart phone.