Re: [Bitcoin-development] determining change addresses using the least significant digits
On Wed, Feb 4, 2015 at 2:23 PM, Isidor Zeuner wrote: > Hi there, > > traditionally, the Bitcoin client strives to hide which output > addresses are change addresses going back to the payer. However, > especially with today's dynamically calculated miner fees, this > may often be ineffective: > > A user sending a payment using the Bitcoin client will usually enter > the payment amount only up to the number of digits which are > considered to be significant enough. So, the least significant digits > will often be zero for the payment. With dynamically calculated miner > fees, this will often not be the case for the change amount, making it > easy for an observer to classify the output addresses. > > A possible approach to handle this issue would be to add a randomized > offset amount to the payment amount. This offset amount can be small > in comparison to the payment amount. Sending someone too much can really play hell with their accounting. Unless you know they're okay with it, I wouldn't suggest it. I often randomly round up the output when I'm paying to a depository account... and I've thought that would be a useful feature to have, but I dunno how to usefully present a UI for "pay at least X but you're allowed to round-up up to 0.01 BTC more". Another strategy is this: create two change outputs, with uniform probablity make one equal to your payment amount (which is also nice because if your payment amount models future payment amount the change will be usefully sized) or split your change evenly. -- Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] determining change addresses using the least significant digits
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 On 02/06/2015 03:08 PM, Jeff Garzik wrote: > Yes. You can certainly add additional inputs and outputs -- and as > such you can increase privacy and defrag your wallet at the same > time. A lot could be done to make regular spends resemble CoinJoin transactions and vice verse. - -- Support online privacy by using email encryption whenever possible. Learn how here: http://www.youtube.com/watch?v=bakOKJFtB-k -BEGIN PGP SIGNATURE- iQIcBAEBCAAGBQJU1P7iAAoJECpf2nDq2eYjeXwQAJGdVdYta5CddfL+xyFNG2+l RMxkSABfgWQF6mDus6ul+EhRhOYEveuuukbK2ibcnY2U4H9ecb8Gttno9+Wi0YfM zcu1Wt/j5cJyUFjO9owZO5gse5mTCt+1njgNIGMlXHHbFEHc5OavXEgkvh8YcL/j E8Kk4YNM5Ovp47vh1ihkB4Zo+ihu5oMuY4vbBO7So4BIe8KaSLOTsOAccT17bWGo jtd6KdjfqsLSjhQoVtuQAsx9AGUS+jfjBRWSnwkeAdd4G4BE87/7DCdYnczFKhds kVwnHODA0+5dwEwZ/ChipKVzAVLVZ2a7BXUenax70P1QgfG8WwL0tueoKviRBLfc 6Xa80GHGo84qeGEkiste1qnG4XZWwi6pnTSTwP1f5CtVvGvfYRysHsMCm82Mr7vA pwrQULv6fkhI63xB+kfcXBPr0WIVrilVrEtGcypzIbPbQgRQ6k3Wg66zLoQTc8vA w2pOZYrEU1Rmfiv27/MLdvSuWzR0kF+nidwCBxUYBuKAA4K0Y8GBH0FApp9JmCEo LXIY4RU3sCCbP3C1qloN8k99q8+CDTwrZpzi2zi3r0zRorg/1tTXqavicE9KPC2j ymk+eFFJhqG51o/d6irzA5R+hK/T2JatDhneEwTBetsrbXq0D9jiN3+KB+vME0wf KJhXhGbElNyz7eA4EOMt =zcqb -END PGP SIGNATURE- 0xEAD9E623.asc Description: application/pgp-keys -- Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] determining change addresses using the least significant digits
Yes. You can certainly add additional inputs and outputs -- and as such you can increase privacy and defrag your wallet at the same time. On Fri, Feb 6, 2015 at 2:11 AM, Wladimir wrote: > On Wed, Feb 4, 2015 at 2:23 PM, Isidor Zeuner > wrote: > > > A possible approach to handle this issue would be to add a randomized > > offset amount to the payment amount. This offset amount can be small > > in comparison to the payment amount. > > > > Any thoughts? > > Adding/subtracting a randomized offset amount is one way, but there > have also been more sophisticated ideas to obfuscate the amount, e.g. > by adding multiple change outputs or even distributing over multiple > transactions (potentially coinjoined for further privacy). > > Mike Hearn had some ideas regarding obfuscation of payment amounts, > which still make sense, and he wrote about them here: > https://medium.com/@octskyward/merge-avoidance-7f95a386692f > > Wladimir > > > -- > Dive into the World of Parallel Programming. The Go Parallel Website, > sponsored by Intel and developed in partnership with Slashdot Media, is > your > hub for all things parallel software development, from weekly thought > leadership blogs to news, videos, case studies, tutorials and more. Take a > look and join the conversation now. http://goparallel.sourceforge.net/ > ___ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/ -- Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] determining change addresses using the least significant digits
On Wed, Feb 4, 2015 at 2:23 PM, Isidor Zeuner wrote: > A possible approach to handle this issue would be to add a randomized > offset amount to the payment amount. This offset amount can be small > in comparison to the payment amount. > > Any thoughts? Adding/subtracting a randomized offset amount is one way, but there have also been more sophisticated ideas to obfuscate the amount, e.g. by adding multiple change outputs or even distributing over multiple transactions (potentially coinjoined for further privacy). Mike Hearn had some ideas regarding obfuscation of payment amounts, which still make sense, and he wrote about them here: https://medium.com/@octskyward/merge-avoidance-7f95a386692f Wladimir -- Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] determining change addresses using the least significant digits
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 On 02/04/2015 02:23 PM, Isidor Zeuner wrote: > Hi there, > > traditionally, the Bitcoin client strives to hide which output > addresses are change addresses going back to the payer. However, > especially with today's dynamically calculated miner fees, this may > often be ineffective: > > A user sending a payment using the Bitcoin client will usually > enter the payment amount only up to the number of digits which are > considered to be significant enough. So, the least significant > digits will often be zero for the payment. With dynamically > calculated miner fees, this will often not be the case for the > change amount, making it easy for an observer to classify the > output addresses. > > A possible approach to handle this issue would be to add a > randomized offset amount to the payment amount. This offset amount > can be small in comparison to the payment amount. Another possible approach is to randomize the number of change outputs from transaction to transaction. Doing this, it would be possible to make change outputs that mimic real spends (low number of s.d.) - -- Support online privacy by using email encryption whenever possible. Learn how here: http://www.youtube.com/watch?v=bakOKJFtB-k -BEGIN PGP SIGNATURE- iQIcBAEBCAAGBQJU1DH9AAoJECpf2nDq2eYjt2gP/3gpojJey2URkWWk0sg9dpHU OsD37TCbrwUaS/K8UMKsuc45FSJU/EeYpaVz9r1Ifm/IeaFYPIX0tEm17n3hkcAG QPmt/xAZn9GVyPWYKjmVDmx574pqiJLeZh8bP788sZsGc4Gk7NNJniVGLtsmvFCb ZOtwS8v7UuJZx6awydrpNhw/+SsQn9Xdb8fcLqmFKWDpG2Mlrv+ds34NMlGbfO2r PqCMw1Y12J0HXLisOCGQNZNdG9mVjKw3MP0GGjUlOM+ibrrorqoO5Ifo2RGuElgw LZkzzDzg6kO8iuNOV7Jg1lz5WftRjgLRSCcMq4V+793zGJW9BeISeDcKQ2ZlWMXB Hu83m4vCYOJeECdKGWlhyTmKNNHshsiPz3SBDLxP8uR80UkS3waDIXwLxGX9Pa63 uleaZ2qHQ/0UdC9opN3Snn33M701dHNJH9iXfhf/MVnUZ0FjzsLXaJ0F0208ZxCX qGCAv5y1ijrDlCLTvakZJRIruXgxNPqtErzP9GtgXeGeDc8tRv00WiM9Olpu0EXd yjhAZGydcE3Ec2cNo+teWjeDt4Ga4OYDb7i08eegaDuj5MCDcDtlgfwNjdKbre1x S7pKKDn8V03/WST1x9fWjM04NxeSjJ0yRjOAxkLV/mlDX6lQEYJL/W+MJLvpOnTC LtZrkSmSTJ7ZR0tMgpAe =8EVe -END PGP SIGNATURE- 0xEAD9E623.asc Description: application/pgp-keys -- Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] determining change addresses using the least significant digits
On Wed, Feb 04, 2015 at 03:23:23PM +0100, Isidor Zeuner wrote: > Hi there, > > traditionally, the Bitcoin client strives to hide which output > addresses are change addresses going back to the payer. However, > especially with today's dynamically calculated miner fees, this > may often be ineffective: > > A user sending a payment using the Bitcoin client will usually enter > the payment amount only up to the number of digits which are > considered to be significant enough. So, the least significant digits > will often be zero for the payment. With dynamically calculated miner > fees, this will often not be the case for the change amount, making it > easy for an observer to classify the output addresses. > > A possible approach to handle this issue would be to add a randomized > offset amount to the payment amount. This offset amount can be small > in comparison to the payment amount. > > Any thoughts? Have you looked at Armory? IIRC they do this kind of stuff. -- 'peter'[:-1]@petertodd.org 165ecbd638ec09226f84c34d3d775d34ca5df4abfa8cb57c signature.asc Description: Digital signature -- Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
[Bitcoin-development] determining change addresses using the least significant digits
Hi there, traditionally, the Bitcoin client strives to hide which output addresses are change addresses going back to the payer. However, especially with today's dynamically calculated miner fees, this may often be ineffective: A user sending a payment using the Bitcoin client will usually enter the payment amount only up to the number of digits which are considered to be significant enough. So, the least significant digits will often be zero for the payment. With dynamically calculated miner fees, this will often not be the case for the change amount, making it easy for an observer to classify the output addresses. A possible approach to handle this issue would be to add a randomized offset amount to the payment amount. This offset amount can be small in comparison to the payment amount. Any thoughts? Best regards, Isidor -- Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
