<div dir="ltr">BIP 140 looks like it solves Tx Malleability with least impact on current practices. It is still a soft fork though.<div><br></div><div>Finally, if we were to create an alternative cyptocurrency similar to Bitcoin, a Normalized Tx ID approach would be a better choice if I get it right!</div></div><div hspace="streak-pt-mark" style="max-height:1px"><img alt="" style="width:0px;max-height:0px;overflow:hidden" src="https://mailfoogae.appspot.com/t?sender=acHJhdmVlbi5iYXJhdGFtQGdtYWlsLmNvbQ%3D%3D&type=zerocontent&guid=1dc0cb1a-dc60-4b69-828a-6db933a55c26"><font color="#ffffff" size="1">ᐧ</font></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Nov 20, 2017 at 11:15 PM, Johnson Lau <span dir="ltr"><<a href="mailto:jl2012@xbt.hk" target="_blank">jl2012@xbt.hk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word;line-break:after-white-space"><div>We can’t “just compute the Transaction ID the same way the hash for signing the transaction is computed” because with different SIGHASH flags, there are 6 (actually 256) ways to hash a transaction.</div><div><br></div><div>Also, changing the definition of TxID is a hardfork change, i.e. everyone are required to upgrade or a chain split will happen.</div><div><br></div>It is possible to use “normalised TxID” (BIP140) to fix malleability issue. As a softfork, BIP140 doesn’t change the definition of TxID. Instead, the normalised txid (i.e. txid with scriptSig removed) is used when making signature. Comparing with segwit (BIP141), BIP140 does not have the side-effect of block size increase, and doesn’t provide any incentive to control the size of UTXO set. Also, BIP140 makes the UTXO set permanently bigger, as the database needs to store both txid and normalised txid<br><div><div><br><blockquote type="cite"><div><div class="h5"><div>On 21 Nov 2017, at 1:24 AM, Praveen Baratam via bitcoin-dev <<a href="mailto:bitcoin-dev@lists.linuxfoundation.org" target="_blank">bitcoin-dev@lists.<wbr>linuxfoundation.org</a>> wrote:</div><br class="m_-4649666739189099192Apple-interchange-newline"></div></div><div><div><div class="h5"><div dir="ltr"><div><span style="font-family:Verdana,arial,sans-serif;font-size:14px">Bitcoin Noob here. Please forgive my ignorance.</span></div><span style="font-family:Verdana,arial,sans-serif;font-size:14px"><div><span style="font-family:Verdana,arial,sans-serif;font-size:14px"><br></span></div>From what I understand, in SegWit, the transaction needs to be serialized into a data structure that is different from the current one where signatures are separated from the rest of the transaction data.</span><div><span style="font-family:Verdana,arial,sans-serif;font-size:14px"><br></span></div><div><span style="font-family:Verdana,arial,sans-serif;font-size:14px">Why change the format at all? Why cant we just compute the Transaction ID the same way the hash for signing the transaction is computed?</span><br clear="all"><div><br></div>-- <br><div class="m_-4649666739189099192gmail_signature"><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Dr. Praveen Baratam</div><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><br></div><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><a href="http://about.me/praveen.baratam" style="color:rgb(17,85,204)" target="_blank">about.me</a></div></div>
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______________________________<wbr>_________________<span class=""><br>bitcoin-dev mailing list<br><a href="mailto:bitcoin-dev@lists.linuxfoundation.org" target="_blank">bitcoin-dev@lists.<wbr>linuxfoundation.org</a><br><a href="https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" target="_blank">https://lists.linuxfoundation.<wbr>org/mailman/listinfo/bitcoin-<wbr>dev</a><br></span></div></blockquote></div><br></div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Dr. Praveen Baratam</div><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><br></div><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><a href="http://about.me/praveen.baratam" style="color:rgb(17,85,204)" target="_blank">about.me</a></div></div>
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