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</o:shapelayout></xml><![endif]--></head><body lang=EN-HK link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Seems it could be done without any new opcode:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Bob is trading b Bitcoins for a altcoins.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>1. Bob Pays D Bitcoins to<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>IF<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><now+2days> CLTV DROP <Alice PK> CHECKSIG<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>ELSE<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>HASH160 <hash secret B> EQUALVERIFY <Bob PK> CHECKSIG<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>ENDIF<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>2. Alice pays a altcoins to<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>IF<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>HASH160 <hash secret B> EQUALVERIFY <Alice PK> CHECKSIG<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>ELSE<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>HASH160 <hash secret A> EQUALVERIFY <Bob PK> CHECKSIG<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>ENDIF<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>3. Bob pays b Bitcoins to<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>IF<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><now+1days> CLTV DROP <Bob PK> CHECKSIG<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>ELSE<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>HASH160 <hash secret A> EQUALVERIFY <Alice PK> CHECKSIG<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>ENDIF<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>4. Alice claims output from step 3 and reveals secret A<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>5. Bob claims output from step 2<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>6. Bob claims output from step 1 and reveals secret B<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'> bitcoin-dev-bounces@lists.linuxfoundation.org [mailto:bitcoin-dev-bounces@lists.linuxfoundation.org] <b>On Behalf Of </b>Tier Nolan via bitcoin-dev<br><b>Sent:</b> Friday, 12 February, 2016 04:05<br><b>To:</b> Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org><br><b>Subject:</b> [bitcoin-dev] BIP CPRKV: Check private key verify<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><div><div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>There was some discussion on the bitcointalk forums about using CLTV for cross chain transfers.<o:p></o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'>Many altcoins don't support CLTV, so transfers to those coins cannot be made secure. <o:p></o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'>I created a protocol. It uses on cut and choose to allow commitments to publish private keys, but it is clunky and not entirely secure.<o:p></o:p></p></div></div><p class=MsoNormal>I created a BIP draft for an opcode which would allow outputs to be locked unless a private key was published that matches a given public key.<o:p></o:p></p><div><div><div><div><p class=MsoNormal><br><a href="https://github.com/TierNolan/bips/blob/cpkv/bip-cprkv.mediawiki">https://github.com/TierNolan/bips/blob/cpkv/bip-cprkv.mediawiki</a><o:p></o:p></p></div></div></div></div></div><div id=DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2><table class=MsoNormalTable border=1 cellpadding=0 style='border:none;border-top:solid #AAABB6 1.0pt'><tr><td width=105 style='width:78.75pt;border:none;padding:11.25pt .75pt .75pt .75pt'><p class=MsoNormal style='margin-top:22.5pt'><a href="https://www.avast.com/sig-email" target="_blank"><span style='text-decoration:none'><img border=0 id="_x0000_i1025" src="https://ipmcdn.avast.com/images/logo-avast-v1.png"></span></a><o:p></o:p></p></td><td width=470 style='width:352.5pt;border:none;padding:15.0pt .75pt .75pt .75pt'><p class=MsoNormal style='margin-top:22.5pt;line-height:13.5pt'><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#41424E'>This email has been sent from a virus-free computer protected by Avast. <br><a href="https://www.avast.com/sig-email" target="_blank"><span style='color:#4453EA'>www.avast.com</span></a> <o:p></o:p></span></p></td></tr></table><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>