Re: [Bitcoin-development] SPV clients and relaying double spends
On 9/25/2014 7:37 PM, Aaron Voisine wrote: Of course you wouldn't want nodes to propagate alerts without independently verifying them How would a node independently verify a double-spend alert, other than by having access to an actual signed double-spend? #4570 relays the first double-spend AS an alert. Running this branch on mainnet, I have been keeping a live list of relayed double-spend transactions at http://respends.thinlink.com -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://pubads.g.doubleclick.net/gampad/clk?id=154622311iu=/4140/ostg.clktrk ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] SPV clients and relaying double spends
Something like that would be a great help for SPV clients that can't detect double spends on their own. (still limited of course to sybil attack concerns) Aaron Voisine breadwallet.com On Thu, Sep 25, 2014 at 7:07 PM, Matt Whitlock b...@mattwhitlock.name wrote: What's to stop an attacker from broadcasting millions of spends of the same output(s) and overwhelming nodes with slower connections? Might it be a better strategy not to relay the actual transactions (after the first) but rather only propagate (once) some kind of double-spend alert? On Thursday, 25 September 2014, at 7:02 pm, Aaron Voisine wrote: There was some discussion of having nodes relay double-spends in order to alert the network about double spend attempts. A lot more users will be using SPV wallets in the future, and one of the techniques SPV clients use to judge how likely a transaction is to be confirmed is if it propagates across the network. I wonder if and when double-spend relaying is introduced, if nodes should also send BIP61 reject messages or something along those lines to indicate which transactions those nodes believe to be invalid, but are relaying anyway. This would be subject to sybil attacks, as is monitoring propagation, however it does still increase the cost of performing a 0 confirmation double spend attack on an SPV client above just relaying double-spends without indicating if a node believes the transaction to be valid. Aaron Voisine breadwallet.com -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://pubads.g.doubleclick.net/gampad/clk?id=154622311iu=/4140/ostg.clktrk ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] SPV clients and relaying double spends
Probably the first double-spend attempt (i.e., the second transaction to spend the same output(s) as another tx already in the mempool) would still need to be relayed. A simple double-spend alert wouldn't work because it could be forged. But after there have been two attempts to spend the same output, no further transactions spending that same output should be relayed, in order to prevent flooding the network. On Thursday, 25 September 2014, at 7:12 pm, Aaron Voisine wrote: Something like that would be a great help for SPV clients that can't detect double spends on their own. (still limited of course to sybil attack concerns) Aaron Voisine breadwallet.com On Thu, Sep 25, 2014 at 7:07 PM, Matt Whitlock b...@mattwhitlock.name wrote: What's to stop an attacker from broadcasting millions of spends of the same output(s) and overwhelming nodes with slower connections? Might it be a better strategy not to relay the actual transactions (after the first) but rather only propagate (once) some kind of double-spend alert? On Thursday, 25 September 2014, at 7:02 pm, Aaron Voisine wrote: There was some discussion of having nodes relay double-spends in order to alert the network about double spend attempts. A lot more users will be using SPV wallets in the future, and one of the techniques SPV clients use to judge how likely a transaction is to be confirmed is if it propagates across the network. I wonder if and when double-spend relaying is introduced, if nodes should also send BIP61 reject messages or something along those lines to indicate which transactions those nodes believe to be invalid, but are relaying anyway. This would be subject to sybil attacks, as is monitoring propagation, however it does still increase the cost of performing a 0 confirmation double spend attack on an SPV client above just relaying double-spends without indicating if a node believes the transaction to be valid. Aaron Voisine breadwallet.com -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://pubads.g.doubleclick.net/gampad/clk?id=154622311iu=/4140/ostg.clktrk ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] SPV clients and relaying double spends
What's to stop an attacker from broadcasting millions of spends of the same output(s) and overwhelming nodes with slower connections? Might it be a better strategy not to relay the actual transactions (after the first) but rather only propagate (once) some kind of double-spend alert? On Thursday, 25 September 2014, at 7:02 pm, Aaron Voisine wrote: There was some discussion of having nodes relay double-spends in order to alert the network about double spend attempts. A lot more users will be using SPV wallets in the future, and one of the techniques SPV clients use to judge how likely a transaction is to be confirmed is if it propagates across the network. I wonder if and when double-spend relaying is introduced, if nodes should also send BIP61 reject messages or something along those lines to indicate which transactions those nodes believe to be invalid, but are relaying anyway. This would be subject to sybil attacks, as is monitoring propagation, however it does still increase the cost of performing a 0 confirmation double spend attack on an SPV client above just relaying double-spends without indicating if a node believes the transaction to be valid. Aaron Voisine breadwallet.com -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://pubads.g.doubleclick.net/gampad/clk?id=154622311iu=/4140/ostg.clktrk ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] SPV clients and relaying double spends
Of course you wouldn't want nodes to propagate alerts without independently verifying them, otherwise anyone could just issue alerts for every new transaction. Aaron Voisine breadwallet.com On Thu, Sep 25, 2014 at 7:16 PM, Matt Whitlock b...@mattwhitlock.name wrote: Probably the first double-spend attempt (i.e., the second transaction to spend the same output(s) as another tx already in the mempool) would still need to be relayed. A simple double-spend alert wouldn't work because it could be forged. But after there have been two attempts to spend the same output, no further transactions spending that same output should be relayed, in order to prevent flooding the network. On Thursday, 25 September 2014, at 7:12 pm, Aaron Voisine wrote: Something like that would be a great help for SPV clients that can't detect double spends on their own. (still limited of course to sybil attack concerns) Aaron Voisine breadwallet.com On Thu, Sep 25, 2014 at 7:07 PM, Matt Whitlock b...@mattwhitlock.name wrote: What's to stop an attacker from broadcasting millions of spends of the same output(s) and overwhelming nodes with slower connections? Might it be a better strategy not to relay the actual transactions (after the first) but rather only propagate (once) some kind of double-spend alert? On Thursday, 25 September 2014, at 7:02 pm, Aaron Voisine wrote: There was some discussion of having nodes relay double-spends in order to alert the network about double spend attempts. A lot more users will be using SPV wallets in the future, and one of the techniques SPV clients use to judge how likely a transaction is to be confirmed is if it propagates across the network. I wonder if and when double-spend relaying is introduced, if nodes should also send BIP61 reject messages or something along those lines to indicate which transactions those nodes believe to be invalid, but are relaying anyway. This would be subject to sybil attacks, as is monitoring propagation, however it does still increase the cost of performing a 0 confirmation double spend attack on an SPV client above just relaying double-spends without indicating if a node believes the transaction to be valid. Aaron Voisine breadwallet.com -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://pubads.g.doubleclick.net/gampad/clk?id=154622311iu=/4140/ostg.clktrk ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
