ð
Original date posted:2018-06-09
ð Original message:Hi Peter,
We reported this as CVE-2017-12842, although it may have been known by
developers before us.
There are hundreds of SPV wallets out there, without even considering other
more sensitive systems relying on SPV proofs.
As I said we, at RSK, discovered this problem in 2017. For RSK it's very
important this is fixed because our SPV bridge uses SPV proofs.
I urge all people participating in this mailing list and the rest of the
Bitcoin community to work on this issue for the security and clean-design
of Bitcoin.
My suggestion is to use in the version bits 4 bits indicating the tree
depth (-1), as a soft-fork, so
00=1 depth,
0F = 16 depth (maximum 64K transactions). Very clean.
The other option is to ban transaction with size lower or equal to 64.
Best regards,
Sergio.
On Sat, Jun 9, 2018 at 5:31 AM Bram Cohen via bitcoin-dev <
bitcoin-dev at lists.linuxfoundation.org> wrote:
> So are you saying that if fully validating nodes wish to prune they can
> maintain the ability to validate old transactions by cacheing the number of
> transactions in each previous block?
>
> On Thu, Jun 7, 2018 at 3:20 PM, Peter Todd <pete at petertodd.org> wrote:
>
>> On Thu, Jun 07, 2018 at 02:15:35PM -0700, Bram Cohen wrote:
>> > Are you proposing a soft fork to include the number of transactions in a
>> > block in the block headers to compensate for the broken Merkle format?
>> That
>> > sounds like a good idea.
>> >
>> > On Thu, Jun 7, 2018 at 10:13 AM, Peter Todd via bitcoin-dev <
>> > bitcoin-dev at lists.linuxfoundation.org> wrote:
>> >
>> > > It's well known that the Bitcoin merkle tree algorithm fails to
>> distinguish
>> > > between inner nodes and 64 byte transactions, as both txs and inner
>> nodes
>> > > are
>> > > hashed the same way. This potentially poses a problem for tx inclusion
>> > > proofs,
>> > > as a miner could (with ~60 bits of brute forcing) create a
>> transaction that
>> > > committed to a transaction that was not in fact in the blockchain.
>> > >
>> > > Since odd-numbered inner/leaf nodes are concatenated with themselves
>> and
>> > > hashed
>> > > twice, the depth of all leaves (txs) in the tree is fixed.
>> > >
>> > > It occured to me that if the depth of the merkle tree is known, this
>> > > vulnerability can be trivially avoided by simply comparing the length
>> of
>> > > the
>> > > merkle path to that known depth. For pruned nodes, if the depth is
>> saved
>> > > prior
>> > > to pruning the block contents itself, this would allow for completely
>> safe
>> > > verification of tx inclusion proofs, without a soft-fork; storing this
>> ^^^^^^^^^^^^^^^^^^^
>>
>> Re-read my post: I specifically said you do not need a soft-fork to
>> implement
>> this. In fact, I think you can argue that this is an accidental feature,
>> not a
>> bug, as it further encourages the use of safe full verifiaction rather
>> than
>> unsafe lite clients.
>>
>> --
>> https://petertodd.org 'peter'[:-1]@petertodd.org
>>
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
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Sergio Demian Lerner [ARCHIVE] /
npub1fvâŠ3vq7f
2023-06-07 18:12:57
in reply to nevent1qâŠ4gqs
Author Public Key
npub1fvuxqdqg7klqqgy3yy8gdxjv4phu92sll5y8zqm2qe5qdrhxymhqf3vq7fPublished at
2023-06-07 18:12:57Event JSON
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Original date posted:2018-06-09\nð Original message:Hi Peter,\nWe reported this as CVE-2017-12842, although it may have been known by\ndevelopers before us.\nThere are hundreds of SPV wallets out there, without even considering other\nmore sensitive systems relying on SPV proofs.\nAs I said we, at RSK, discovered this problem in 2017. For RSK it's very\nimportant this is fixed because our SPV bridge uses SPV proofs.\nI urge all people participating in this mailing list and the rest of the\nBitcoin community to work on this issue for the security and clean-design\nof Bitcoin.\n\nMy suggestion is to use in the version bits 4 bits indicating the tree\ndepth (-1), as a soft-fork, so\n00=1 depth,\n0F = 16 depth (maximum 64K transactions). Very clean.\n\nThe other option is to ban transaction with size lower or equal to 64.\n\nBest regards,\n Sergio.\n\nOn Sat, Jun 9, 2018 at 5:31 AM Bram Cohen via bitcoin-dev \u003c\nbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\n\u003e So are you saying that if fully validating nodes wish to prune they can\n\u003e maintain the ability to validate old transactions by cacheing the number of\n\u003e transactions in each previous block?\n\u003e\n\u003e On Thu, Jun 7, 2018 at 3:20 PM, Peter Todd \u003cpete at petertodd.org\u003e wrote:\n\u003e\n\u003e\u003e On Thu, Jun 07, 2018 at 02:15:35PM -0700, Bram Cohen wrote:\n\u003e\u003e \u003e Are you proposing a soft fork to include the number of transactions in a\n\u003e\u003e \u003e block in the block headers to compensate for the broken Merkle format?\n\u003e\u003e That\n\u003e\u003e \u003e sounds like a good idea.\n\u003e\u003e \u003e\n\u003e\u003e \u003e On Thu, Jun 7, 2018 at 10:13 AM, Peter Todd via bitcoin-dev \u003c\n\u003e\u003e \u003e bitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\u003e \u003e\n\u003e\u003e \u003e \u003e It's well known that the Bitcoin merkle tree algorithm fails to\n\u003e\u003e distinguish\n\u003e\u003e \u003e \u003e between inner nodes and 64 byte transactions, as both txs and inner\n\u003e\u003e nodes\n\u003e\u003e \u003e \u003e are\n\u003e\u003e \u003e \u003e hashed the same way. This potentially poses a problem for tx inclusion\n\u003e\u003e \u003e \u003e proofs,\n\u003e\u003e \u003e \u003e as a miner could (with ~60 bits of brute forcing) create a\n\u003e\u003e transaction that\n\u003e\u003e \u003e \u003e committed to a transaction that was not in fact in the blockchain.\n\u003e\u003e \u003e \u003e\n\u003e\u003e \u003e \u003e Since odd-numbered inner/leaf nodes are concatenated with themselves\n\u003e\u003e and\n\u003e\u003e \u003e \u003e hashed\n\u003e\u003e \u003e \u003e twice, the depth of all leaves (txs) in the tree is fixed.\n\u003e\u003e \u003e \u003e\n\u003e\u003e \u003e \u003e It occured to me that if the depth of the merkle tree is known, this\n\u003e\u003e \u003e \u003e vulnerability can be trivially avoided by simply comparing the length\n\u003e\u003e of\n\u003e\u003e \u003e \u003e the\n\u003e\u003e \u003e \u003e merkle path to that known depth. For pruned nodes, if the depth is\n\u003e\u003e saved\n\u003e\u003e \u003e \u003e prior\n\u003e\u003e \u003e \u003e to pruning the block contents itself, this would allow for completely\n\u003e\u003e safe\n\u003e\u003e \u003e \u003e verification of tx inclusion proofs, without a soft-fork; storing this\n\u003e\u003e ^^^^^^^^^^^^^^^^^^^\n\u003e\u003e\n\u003e\u003e Re-read my post: I specifically said you do not need a soft-fork to\n\u003e\u003e implement\n\u003e\u003e this. In fact, I think you can argue that this is an accidental feature,\n\u003e\u003e not a\n\u003e\u003e bug, as it further encourages the use of safe full verifiaction rather\n\u003e\u003e than\n\u003e\u003e unsafe lite clients.\n\u003e\u003e\n\u003e\u003e --\n\u003e\u003e https://petertodd.org 'peter'[:-1]@petertodd.org\n\u003e\u003e\n\u003e\n\u003e _______________________________________________\n\u003e bitcoin-dev mailing list\n\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20180609/b0d55588/attachment-0001.html\u003e",
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