Bitcoin Forum

Privacy and fungiblity are essential components for any money-like system.
Without them, your transactions leak information about your private
activities and leave you at risk of discriminatory treatment. Without them your security is reduced due to selective targeting and your commercial negotiations can be undermined.

They're important and were consideration's in Bitcoin's design since day one. But Bitcoin's initial approach to preserving privacy and fungiblity -- pseudonymous addresses-- is limited, and full exploitation of it requires less convenient usage patterns that have fallen out of favor.

There are many technologies people have been working on to improve fungiblity and privacy in different ways-- coinjoins[url=http://and [url=https://bitcointalk.org/index.php?topic=321228.0]swaps] and [url=https://bitcointalk.org/index.php?topic=321228.0]swaps (https://bitcointalk.org/index.php?topic=279249.0), confidential
transactions (https://bitcointalk.org/index.php?topic=1085273.0)), encrypted/committed transactions (http://diyhpl.us/wiki/transcripts/bitcoin-adam3us-fungibility-privacy/), schnorr
multisignature, MAST (https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-April/012598.html)), better wallet input selection logic, private wallet scanning, tools for address reuse avoidance, P2P encryption (https://github.com/bitcoin/bips/blob/master/bip-0151.mediawiki)], ECDH-derived addresses, P2P surveillance resistance, to name a few.

Having some more in-the-field examples will help prioritize these efforts. So I'm asking here for more examples of where privacy and fungiblity loss have hurt Bitcoin users or just discouraged Bitcoin use-- and, if known, the specifics about how those situations came about.

Please feel free to provide links to other people's examples too, and also feel free to contact me privately ( gmaxwell@blockstream.com GPG: 0xAC859362B0413BFA ).

I also posted this question on Reddit (https://www.reddit.com/r/Bitcoin/comments/4v28jl/how_have_fungiblity_problems_affected_you_in/), but though I might get a broader audience here.