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From: Andrea <a.raspitzu@protonmail.com>
To: William Casarin <jb55@jb55.com>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] BIP 174 thoughts
Date: Wed, 27 Jun 2018 09:39:02 -0400	[thread overview]
Message-ID: <SBu1mxevY6vaDj8jipOqQacRY02PPUHcsq30eXRaC5jwE5JKCfNuM9RNKVSQvQfup1fBfWEcANimrKbdQFFbdg4bmb2yvv7UVdLRHyuMIyc=@protonmail.com> (raw)
In-Reply-To: <87k1qk7oca.fsf@jb55.com>

Hi William, Andrew, list,

As noted by William there are some types missing in the global-types definition, because the number of each map for I/O must be known to the parser in order to use the correct definitions for the types. At the moment a parser reading a key-value record does not know whether it should read it as per-input type or per-output, a way to address this is to declare in advance the number of maps and ensure they are ordered (inputs first). If you haven't already worked out some types for that i propose using:

Number of inputs
- key (None, only the type): PSBT_GLOBAL_INPUT_NUMBER = 0x01  
- value: Varint 

Number of outputs
- key (none, only the type): PSBT_GLOBAL_OUTPUT_NUMBER = 0x02
- value: Varint

On another note I think we can set a hard limit on the size of the PSBT, currently is 'legal' to produce a very large PSBT with an excessive number of Inputs and Outputs. By excessive I mean that even in the best case scenario (using the smallest possible scriptPubKey as in P2WPKH) it is possible to create a PSBT that would certainly create an invalid transaction (because of its size) when finalized. I haven't found anything related to this in the previous discussions, please ignore this if it was already proposed/discussed.


Cheers, Andrea.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On June 27, 2018 8:09 AM, William Casarin via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:

> ​​
> 
> Hey Andrew,
> 
> If I'm reading the spec right: the way it is designed right now, you
> 
> could create hundreds of thousands of zero bytes in the input or output
> 
> key-value arrays. As far as I can tell this would be considered valid,
> 
> as it is simply a large array of empty dictionaries. Is this right? I'm
> 
> worried about buffer overflows in cases where someone sends a large blob
> 
> of zeros to an unsuspecting implementation.
> 
> Also, the extensibility section reads:
> 
> > Additional key-value maps with different types for the key-value pairs
> > 
> > can be added on to the end of the format.
> 
> "different types for the key-value pairs", is this referring to new
> 
> types beyond the current global, input and output types?
> 
> > The number of each map that follows must be specified in the globals
> > 
> > section
> 
> Is this out of date? Since there is only one type in the global section
> 
> now (tx).
> 
> > so that parsers will know when to use different definitions of the
> > 
> > data types
> 
> I'm not sure what this means.
> 
> Thanks!
> 
> Will
> 
> 
> ------------------------------------------------
> 
> https://jb55.com
> 
> bitcoin-dev mailing list
> 
> bitcoin-dev@lists.linuxfoundation.org
> 
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev




  reply	other threads:[~2018-06-27 13:39 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-15 23:34 [bitcoin-dev] BIP 174 thoughts Pieter Wuille
2018-06-16 15:00 ` Peter D. Gray
2018-06-19  9:38 ` Jonas Schnelli
2018-06-19 14:20 ` matejcik
2018-06-19 15:20   ` Jonas Schnelli
2018-06-21 20:28     ` Peter D. Gray
2018-06-19 17:16   ` Pieter Wuille
2018-06-21 11:29     ` matejcik
2018-06-21 17:39       ` Pieter Wuille
2018-06-21 11:44     ` Tomas Susanka
2018-06-19 14:22 ` matejcik
2018-06-21  0:39 ` Achow101
2018-06-21 14:32   ` Tomas Susanka
2018-06-21 15:40     ` Greg Sanders
2018-06-21 19:56     ` Peter D. Gray
2018-06-21 21:39       ` Gregory Maxwell
2018-06-22 19:10       ` Pieter Wuille
2018-06-22 22:28         ` Achow101
2018-06-23 17:00           ` William Casarin
2018-06-23 20:33             ` Andrew Chow
2018-06-24  8:19               ` Andrea
2018-06-24  8:28                 ` Andrew Chow
2018-06-24  9:00                   ` Andrea
2018-06-23 18:27           ` Peter D. Gray
2018-06-25 19:47           ` Tomas Susanka
2018-06-25 20:10             ` Jonas Schnelli
2018-06-25 20:30             ` Achow101
2018-06-26 15:33               ` matejcik
2018-06-26 16:58                 ` William Casarin
2018-06-26 17:11                   ` Marek Palatinus
2018-06-27 14:11                   ` matejcik
2018-06-26 20:30                 ` Pieter Wuille
2018-06-27 14:04                   ` matejcik
2018-06-27 15:06                     ` Pieter Wuille
2018-06-29  9:53                       ` matejcik
2018-06-29 19:12                         ` Achow101
2018-06-29 20:31                           ` Peter D. Gray
2018-07-04 13:19                           ` matejcik
2018-07-04 18:35                             ` Achow101
2018-07-05 17:23                               ` Jason Les
2018-07-04 19:09                             ` Pieter Wuille
2018-07-05 11:52                               ` matejcik
2018-07-05 22:06                                 ` Pieter Wuille
2018-07-10 12:10                                   ` matejcik
2018-07-11 18:27                                     ` Pieter Wuille
2018-07-11 20:05                                       ` Gregory Maxwell
2018-07-11 20:54                                         ` [bitcoin-dev] BIP 174 thoughts on graphics vv01f
2018-06-26 21:56                 ` [bitcoin-dev] BIP 174 thoughts Achow101
2018-06-27  6:09                   ` William Casarin
2018-06-27 13:39                     ` Andrea [this message]
2018-06-27 17:55                     ` Achow101
2018-06-28 20:42                       ` Rodolfo Novak
2018-07-05 19:20                       ` William Casarin
2018-07-06 18:59                         ` Achow101
2018-06-20  0:39 Jason Les

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