Andy Schroder [ARCHIVE] on Nostr: š Original date posted:2017-12-27 š Original message: Andy Schroder On ...
š
Original date posted:2017-12-27
š Original message:
Andy Schroder
On 12/27/2017 01:06 AM, ZmnSCPxj wrote:
> Good morning Andy,
>
>> Andy Schroder
>> On 12/27/2017 12:18 AM, Andy Schroder wrote:
>>>> Channel closing
>>>> costs dwarf the gains to be made from cheating, however.
>>>>
>>>>
>>>>> Since millisatoshis is used, is there a maximum channel funding size?
>>>> Yes, the upper 32 bits must be zero, from BOLT #2:
>>>>
>>>> - for channels with `chain_hash` identifying the Bitcoin
>>>> blockchain:
>>>> - MUST set the four most significant bytes of `amount_msat` to 0.
>>>>
>>>> This gives a maximum HTLC value of .04294967295 BTC, which, back when
>>>> we started, was about $10.
>>>>
>>>
>>> What's the point of wasting the upper 32 bits? Seems like this is a
>>> waste of data?
>>>
>>> If you have the lower 32 bits of data to use, and
>>> 2^32=4,294,967,296, then you have 4,294,967,296 milli satoshis. 1
>>> BTC=10^11 milli satoshis, so 4,294,967,296 milli satoshis/((10^11
>>> milli satoshis)/1BTC) = 0.04294967296 BTC. That is off by 1 milli
>>> satoshi from what you say above. Why is this?
>>>
>>> Regardless of the discrepancy of 1 milli satoshi, it still seems
>>> like 0.04294967296 BTC is kind of a low maximum channel size for a
>>> lot of business applications. Why do you want to limit this when you
>>> have those extra 4 bytes set to zero? You think any more is too much
>>> to safely have in a hot wallet? You felt keeping it low will
>>> encourage decentralization? Something else?
>>>
>
> Yes, I believe Rusty did indeed consider 42mBTC as a reasonable amount
> to transfer on Lightning. So that in case of trouble on Lightning,
> not a lot of money gets lost. At the time he decided this 42mBTC
> limit, it was about 10 USD only, so Rusty could always just buy you a
> drink if he somehow causes c-lightning to lose that much.
>
> Of course, 42mBTC today is much larger.
>
> For myself, I think the channel limit of 167mBTC is good as it
> encourages decentralization by encouraging people to make many small
> channels than one large channel. Many small channels helps in keeping
> your funds resilient against temporary outages of your fellow nodes.
I understand what you are saying about decentralization, but is this
really something that will be enforceable? Seems like people will just
make an alt-lightning network layer with different limits to get around
this, since there isn't really a consensus rule set like on the block
chain to motivate them.
>
>>>
>>> Is the max HTLC value the same as the maximum channel size?
>>
>> Okay, so I may have discovered part of this answer to this question
>> in BOLT 2 where it says: "MUST set|funding_satoshis| to less than
>> 2^24 satoshi". However, I still don't understand the rational of why
>> |max ||funding_satoshis doesn't equal max |amount_msat, or where the
>> values of (2^24)*10^3 and 2^32 milli satoshis came from. Also, why
>> don't you use units of millisatoshis everywhere in the spec?
>> Sometimes it's satoshis and sometimes it's milli satoshis.
>>
>
> This is actually very simple. Everything that touches the chain
> (opening and closing) uses satoshis. Everything that does not, uses
> millisatoshis. This is because the chain uses satoshis as the
> smallest amount. Offchain, we can use millisatoshis, and it is used
> everywhere offchain.
Okay, the unit choices now make sense!
>
> Regards,
> ZmnSCPxj
>
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š Original message:
Andy Schroder
On 12/27/2017 01:06 AM, ZmnSCPxj wrote:
> Good morning Andy,
>
>> Andy Schroder
>> On 12/27/2017 12:18 AM, Andy Schroder wrote:
>>>> Channel closing
>>>> costs dwarf the gains to be made from cheating, however.
>>>>
>>>>
>>>>> Since millisatoshis is used, is there a maximum channel funding size?
>>>> Yes, the upper 32 bits must be zero, from BOLT #2:
>>>>
>>>> - for channels with `chain_hash` identifying the Bitcoin
>>>> blockchain:
>>>> - MUST set the four most significant bytes of `amount_msat` to 0.
>>>>
>>>> This gives a maximum HTLC value of .04294967295 BTC, which, back when
>>>> we started, was about $10.
>>>>
>>>
>>> What's the point of wasting the upper 32 bits? Seems like this is a
>>> waste of data?
>>>
>>> If you have the lower 32 bits of data to use, and
>>> 2^32=4,294,967,296, then you have 4,294,967,296 milli satoshis. 1
>>> BTC=10^11 milli satoshis, so 4,294,967,296 milli satoshis/((10^11
>>> milli satoshis)/1BTC) = 0.04294967296 BTC. That is off by 1 milli
>>> satoshi from what you say above. Why is this?
>>>
>>> Regardless of the discrepancy of 1 milli satoshi, it still seems
>>> like 0.04294967296 BTC is kind of a low maximum channel size for a
>>> lot of business applications. Why do you want to limit this when you
>>> have those extra 4 bytes set to zero? You think any more is too much
>>> to safely have in a hot wallet? You felt keeping it low will
>>> encourage decentralization? Something else?
>>>
>
> Yes, I believe Rusty did indeed consider 42mBTC as a reasonable amount
> to transfer on Lightning. So that in case of trouble on Lightning,
> not a lot of money gets lost. At the time he decided this 42mBTC
> limit, it was about 10 USD only, so Rusty could always just buy you a
> drink if he somehow causes c-lightning to lose that much.
>
> Of course, 42mBTC today is much larger.
>
> For myself, I think the channel limit of 167mBTC is good as it
> encourages decentralization by encouraging people to make many small
> channels than one large channel. Many small channels helps in keeping
> your funds resilient against temporary outages of your fellow nodes.
I understand what you are saying about decentralization, but is this
really something that will be enforceable? Seems like people will just
make an alt-lightning network layer with different limits to get around
this, since there isn't really a consensus rule set like on the block
chain to motivate them.
>
>>>
>>> Is the max HTLC value the same as the maximum channel size?
>>
>> Okay, so I may have discovered part of this answer to this question
>> in BOLT 2 where it says: "MUST set|funding_satoshis| to less than
>> 2^24 satoshi". However, I still don't understand the rational of why
>> |max ||funding_satoshis doesn't equal max |amount_msat, or where the
>> values of (2^24)*10^3 and 2^32 milli satoshis came from. Also, why
>> don't you use units of millisatoshis everywhere in the spec?
>> Sometimes it's satoshis and sometimes it's milli satoshis.
>>
>
> This is actually very simple. Everything that touches the chain
> (opening and closing) uses satoshis. Everything that does not, uses
> millisatoshis. This is because the chain uses satoshis as the
> smallest amount. Offchain, we can use millisatoshis, and it is used
> everywhere offchain.
Okay, the unit choices now make sense!
>
> Regards,
> ZmnSCPxj
>
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