{"type":"rich","version":"1.0","title":"Konstantin Ketterer [ARCHIVE] wrote","author_name":"Konstantin Ketterer [ARCHIVE] (npub1d3…v3l5r)","author_url":"https://yabu.me/npub1d38xn8fn3qsj4ruge6qces8qwljx993gkxkek8usmkrzllrn2d3q8v3l5r","provider_name":"njump","provider_url":"https://yabu.me","html":"📅 Original date posted:2019-09-25\n📝 Original message:\n*Disclaimer*: I have just finished Highschool and I'm only learning a bit\nin my free time.This may be fundamentally broken ;)\n\n*Motivation*: If I had to timestamp multiple messages I could simply\naggregate them in a merkle tree and pay relatively low fees per message.\nHowever, if I only need to timestamp something once in a while I need to\nrely on free services or pay high fees.\n\n*Solution*: buy a place in a merkle tree \"risk-free\"\n\n1. send hash x of my message (or the merkle root of another tree) to the\ntimstamping server\n2. server calculates Pedersen commit: C = x*H + r*G, hashes it, builds\nmerkle tree with other commits in it and publishes a valid transaction\ncontaining the merkle root to the Bitcoin blockchain\n3. after a certain number of block confirmations and with the given proof I\ncan confirm that the commitment C is indeed part of the Bitcoin blockchain\n4. I now have to send a lightning payment with C - x*H = r*G as the payment\npoint  to the timestamping server and as a proof of payment the server must\nreveal r to receive the money.\n\n--\u003e With both r and x I have a valid Pedersen commitment.\n\nThis introduces an additional security assumption to Bitcoin timestamps but\nif the discrete logarithm is broken Bitcoin has bigger problems than broken\ntimestamps.\n\n*Conclusion*\nThis scheme essentially shifts the risk of a timestamping service from the\nbuyer to the seller who now has to pay the onchain transaction fee upfront.\nHence, the seller will most likely charge a small fee upfront just like\nsome submarineswap providers do.\n\nRegards\nKonstantin Ketterer\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/lightning-dev/attachments/20190925/8d6502f0/attachment.html\u003e"}