From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1XGHo4-0001Xv-4g for bitcoin-development@lists.sourceforge.net; Sun, 10 Aug 2014 01:20:20 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.192.173 as permitted sender) client-ip=209.85.192.173; envelope-from=elombrozo@gmail.com; helo=mail-pd0-f173.google.com; Received: from mail-pd0-f173.google.com ([209.85.192.173]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1XGHo2-00070Y-VJ for bitcoin-development@lists.sourceforge.net; Sun, 10 Aug 2014 01:20:20 +0000 Received: by mail-pd0-f173.google.com with SMTP id w10so8888587pde.18 for ; Sat, 09 Aug 2014 18:20:13 -0700 (PDT) X-Received: by 10.66.245.140 with SMTP id xo12mr33158798pac.38.1407633613163; Sat, 09 Aug 2014 18:20:13 -0700 (PDT) Received: from [192.168.1.108] (cpe-76-167-237-202.san.res.rr.com. [76.167.237.202]) by mx.google.com with ESMTPSA id 5sm10762781pds.12.2014.08.09.18.20.10 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 09 Aug 2014 18:20:11 -0700 (PDT) Content-Type: multipart/signed; boundary="Apple-Mail=_0C2F2A54-EE8A-41AC-8CCC-9E22ABFC1B1C"; protocol="application/pgp-signature"; micalg=pgp-sha1 Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) From: Eric Lombrozo In-Reply-To: Date: Sat, 9 Aug 2014 18:20:09 -0700 Message-Id: <501F55C1-6307-487B-91D8-9CC0193DA747@gmail.com> References: To: second isogeny X-Mailer: Apple Mail (2.1510) X-Spam-Score: -1.6 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (elombrozo[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1XGHo2-00070Y-VJ Cc: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] BIP32 - invalidation X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 10 Aug 2014 01:20:20 -0000 --Apple-Mail=_0C2F2A54-EE8A-41AC-8CCC-9E22ABFC1B1C Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Does bitcoin properly handle the case of a hash collision? no - because = it is considered too unlikely. The case of I_L >=3D n is also = astronomically unlikely, so it's more a matter of improved performance = and simpler data structures under expected circumstances and taking that = less than 1 in 2^127 chance that it will fail, in which case we can = recover by moving everything over to a new tree. -Eric Lombrozo On Aug 9, 2014, at 5:34 PM, second isogeny = wrote: > > Does anyone see any concerns when it comes to security of the = proposed > > change? >=20 > Yes. This proposal is less secure. >=20 > It is incompatible in theory with existing implementations of the > specification. The incompatibility is also a potentially a security > problem because it may cause users to believe a key is worthless when > it is not or to lose funds when they are unable to spend them. >=20 > It is also an untimely proposal and would be inconsiderate other = parties > who have done the work to produce correct and compatible = implementations. >=20 > > In case I_L >=3D n assign I_L :=3D I_L mod n. >=20 > This will make the selection of private keys uneven. >=20 > The unevenness is small and it is unlikely to very matter much but it > is objectively less secure. Future advances in cryptography may make > the distinction more important. The change would eliminate any hope = of > the specification ever having provable security equal to random keys. >=20 > The bignum modulo operation also requires complex additional logic and = is > just as likely to remain untested in implementations, though = unit-testing > can test these cases by replacing the hash function. >=20 > Because of layering no suitable modulo may be available and an = incorrect > implementation could create a devastating weakness, like reflecting a > large class of keys to a small number of values. A similar error = would > be unlikely for an incorrect implementation of skipping and someone = who > managed to still fail would likely have failed either way. >=20 > > most of the implementations don't do the checking at all, because = tjen > > it's rather hard at application level to implement skipping logic. = OTOH >=20 > There are many corner cases which must be handled in cryptographic > software. >=20 > You must handle the point at infinity cases, you must handle the = signature > having a value of zero (or you leak the private key), in the point > arithemetics you must handle the special case of adding colinear = points. >=20 > If someone is unprepared to deal with these and many other = complications > they may want to leave writing this kind of software for other people. >=20 > = --------------------------------------------------------------------------= ---- > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development --Apple-Mail=_0C2F2A54-EE8A-41AC-8CCC-9E22ABFC1B1C Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- iQIcBAEBAgAGBQJT5sjJAAoJEAA1EyJsW9n+zvgP/RKwczorptcZHBJkyQ4fu9QJ DJNYEsC1CtqBwwaUG0mqtLTQ/3kyaXE1NPLEnQZadn5e77CWbZ+olvzev2/1Vg/A kXdV/YVv2NpmxXgY1PMX1wxeJ+F0k4EKZ0erFFN5BB3oFWKsjDteC+UlyyUXnuiX hqkKaA4jJf7B9p7kjSpwwW5r52oNrREuvxEbjCZ281aQwo5BdXtk9EE/jmgGejLS DvPUDEE04S8wL+pc0+saQlTccvgX5kI4rjVC7nHtvKa6GCpxgTtRk3NOF/TqWdd/ yebb9crD3lhK3SFxftec+z4bFZ0lvVS4MHuDRCtFJMpmdPMNVJVT+qDiJyVAf6JD WBA/UhsA0hemg42eaj1iahtUCsm45LPCPJ6mhOU5FUNSFspl6kXf5Lzn6TXe4RL4 NzvwzDaED8eOC4pLFxQB4FFnpg/PBzW54ETF0nkvh6zMhXjzbqqxfTOi/x7lXjh6 7Vk8zmtcdU8zpkYzRJ5s8o9y6VBix8RZp7GsV5iripI3Px024VyBHZz/Usuqbrop ascgdG6Dy8/sOD6Yc4p7cpxyzRfVwSaTQWjsSljqss/9bucOabswwqkQK5RfTVEr vN9gOhlQIajTg7j0n3rkyQK85tG8oU7Qa1gEy/0eNIaRgJvhYyLaefAQbQiMWoLt yGmXUrBduHQ1rVFlsP/y =BYJj -----END PGP SIGNATURE----- --Apple-Mail=_0C2F2A54-EE8A-41AC-8CCC-9E22ABFC1B1C--