{"type":"rich","version":"1.0","author_name":"npub1m230cem2yh3mtdzkg32qhj73uytgkyg5ylxsu083n3tpjnajxx4qqa2np2","author_url":"https://nostr.ae/npub1m230cem2yh3mtdzkg32qhj73uytgkyg5ylxsu083n3tpjnajxx4qqa2np2","provider_name":"njump","provider_url":"https://nostr.ae","html":"📅 Original date posted:2014-01-20\n📝 Original message:On Sat, Jan 18, 2014 at 05:12:58PM -0600, Jeremy Spilman wrote:\n\u003e \n\u003e \n\u003e \u003e On Fri, Jan 17, 2014 at 8:55 PM, Alan Reiner \u003cetotheipi at gmail.com\u003e wrote:\n\u003e \u003e\u003e Isn't there a much faster asymmetric scheme that we can use?  I've heard people talk about ed25519, though I'm not sure it can be used for encryption.\n\u003e \u003e \n\u003e \u003e Doing ECDH with our curve is within a factor of ~2 of the fastest\n\u003e \u003e encryption available at this security level, AFAIK.  And separate\n\u003e \u003e encryption would ~double the amount of data vs using the ephemeral key\n\u003e \u003e for derivation.\n\u003e \u003e \n\u003e \u003e Using another cryptosystem would mandate carry around additional code\n\u003e \u003e for a fast implementation of that cryptosystem, which wouldn't be\n\u003e \u003e fantastic.\n\u003e \u003e \n\u003e \u003e So I'm not sure much can be improved there.\n\u003e \n\u003e In the case where payment is being sent only to Q1, and Q2 is for discovery only, perhaps we could use a 160-bit curve for d2/Q2 and e/P resulting in 20 byte vs 32 bytes in the OP_RETURN, and of course faster multiplication. \n\u003e \n\u003e 80-bits of security I assume still greatly exceeds the actual level of privacy you get with the overall solution, and since Q2 is never protecting actual funds...\n\u003e \n\u003e But if it's a \"real weakening\" of the privacy then definitely not worth it, and even the added complexity of another curve seems possibly not worth it...\n\nKeep in mind that Bitmessage uses the same ECDH mechanism as what\nstealth addresses will use. They seem to get decent enough performance\nfrom it for a use-case not-unlike that of a Bitcoin wallet.\n\nIn any case I'm interested in knowing actual performance numbers for it;\nlast I talked to Kyle Drake he said he was working on getting ECDH\nnumbers on Javascript, probably the slowest possible implementation of\nthe idea. As for send to stealth addresses using prefixes, he's\nconfirmed that you'll be able to do that will well under a second to\nbrute-force the prefixes with the proposed OP_RETURN mechanism even with\nrather long 8-bit prefixes.\n\n-- \n'peter'[:-1]@petertodd.org\n000000000000000190a2900f1a25c507a999fa11116f7bd0126618c1ebc4f5fb\n-------------- next part --------------\nA non-text attachment was scrubbed...\nName: signature.asc\nType: application/pgp-signature\nSize: 685 bytes\nDesc: Digital signature\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20140120/69317ce0/attachment.sig\u003e"}