š
Original date posted:2018-06-02
š Original message:On Fri, Jun 01, 2018 at 07:02:38PM -0700, Jim Posen via bitcoin-dev wrote:
> Without the ability to verify filter validity, a client would have to stop
> syncing altogether in the presence of just one malicious peer, which is
> unacceptable.
I'm confused about why this would be the case. If Alice's node
generates filters accurately and Mallory's node generates filters
inaccurately, and they both send their filters to Bob, won't Bob be able
to download any blocks either filter indicates are relevant to his
wallet?
If Bob downloads a block that contains one of his transactions based on
Alice's filter indicating a possible match at a time when Mallory's
filter said there was no match, then this false negative is perfect
evidence of deceit on Mallory's part[1] and Bob can ban her.
If Bob downloads a block that doesn't contain any of his transactions
based on Mallory's filter indicating a match at a time when Alice's
filter said there was no match, then this false positive can be recorded
and Bob can eventually ban Mallory should the false positive rate
exceeds some threshold.
Until Mallory is eventually banned, it seems to me that the worst she
can do is waste Bob's bandwidth and that of any nodes serving him
accurate information, such as Alice's filters and the blocks Bob
is misled into downloading to check for matches. The amount of
attacker:defender asymetry in the bandwidth wasted increases if
Mallory's filters become less accurate, but this also increases her
false positive rate and reduces the number of filters that need to be
seen before Bob bans her, so it seems to me (possibly naively) that this
is not a significant DoS vector.
-Dave
[1] Per BIP158 saying, "a Golomb-coded set (GCS), which matches all
items in the set with probability 1"
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David A. Harding [ARCHIVE] /
npub16dā¦x4wrd
2023-06-07 18:12:38
in reply to nevent1qā¦7lzw
Author Public Key
npub16dt55fpq3a8r6zpphd9xngxr46zzqs75gna9cj5vf8pknyv2d7equx4wrdPublished at
2023-06-07 18:12:38Event JSON
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Original date posted:2018-06-02\nš Original message:On Fri, Jun 01, 2018 at 07:02:38PM -0700, Jim Posen via bitcoin-dev wrote:\n\u003e Without the ability to verify filter validity, a client would have to stop\n\u003e syncing altogether in the presence of just one malicious peer, which is\n\u003e unacceptable.\n\nI'm confused about why this would be the case. If Alice's node\ngenerates filters accurately and Mallory's node generates filters\ninaccurately, and they both send their filters to Bob, won't Bob be able\nto download any blocks either filter indicates are relevant to his\nwallet?\n\nIf Bob downloads a block that contains one of his transactions based on\nAlice's filter indicating a possible match at a time when Mallory's\nfilter said there was no match, then this false negative is perfect\nevidence of deceit on Mallory's part[1] and Bob can ban her.\n\nIf Bob downloads a block that doesn't contain any of his transactions\nbased on Mallory's filter indicating a match at a time when Alice's\nfilter said there was no match, then this false positive can be recorded\nand Bob can eventually ban Mallory should the false positive rate\nexceeds some threshold.\n\nUntil Mallory is eventually banned, it seems to me that the worst she\ncan do is waste Bob's bandwidth and that of any nodes serving him\naccurate information, such as Alice's filters and the blocks Bob\nis misled into downloading to check for matches. The amount of\nattacker:defender asymetry in the bandwidth wasted increases if\nMallory's filters become less accurate, but this also increases her\nfalse positive rate and reduces the number of filters that need to be\nseen before Bob bans her, so it seems to me (possibly naively) that this\nis not a significant DoS vector.\n\n-Dave\n\n[1] Per BIP158 saying, \"a Golomb-coded set (GCS), which matches all\nitems in the set with probability 1\"\n-------------- next part --------------\nA non-text attachment was scrubbed...\nName: signature.asc\nType: application/pgp-signature\nSize: 833 bytes\nDesc: not available\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20180602/9556f60f/attachment.sig\u003e",
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