Re: [bitcoin-dev] Simplicity proposal - Jets?

From: Mark Friedenbach <mark@friedenbach•org>
To: "Hampus Sjöberg" <hampus.sjoberg@gmail•com>,
	"Bitcoin Protocol Discussion"
	<bitcoin-dev@lists•linuxfoundation.org>
Cc: "JOSE FEMENIAS CAÑUELO" <jose.femenias@gmail•com>
Subject: Re: [bitcoin-dev] Simplicity proposal - Jets?
Date: Fri, 3 Nov 2017 09:19:39 -0700	[thread overview]
Message-ID: <4F2B4652-BEB4-4202-AA30-0E8D0BEBDD17@friedenbach.org> (raw)
In-Reply-To: <CAFMkqK_rXb9fAiGC_qNf5nj_cShJgAB4qTUsCM+R07DSAau2TA@mail.gmail.com>

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To reiterate, none of the current work focuses on Bitcoin integration, and many architectures are possible.

However the Jets would have to be specified and agreed to upfront for costing reasons, and so they would be known to all validators. There would be no reason to include anything more then the identifying hash in any contract using the jet.

> On Nov 3, 2017, at 5:59 AM, Hampus Sjöberg via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org> wrote:
> 
> Thank you for your answer, Russel.
> 
> When a code path takes advantage of a jet, does the Simplicity code still need to be publicly available/visible in the blockchain? I imagine that for big algorithms (say for example EDCA verification/SHA256 hashing etc), it would take up a lot of space in the blockchain.
> Is there any way to mitigate this?
> 
> I guess in a softfork for a jet, the Simplicity code for a jet could be defined as "consensus", instead of needed to be provided within every script output.
> When the Simplicity interpretor encounters an expression that has a jet, it would run the C/Assembly code instead of interpreting the Simplicity code. By formal verification we would be sure they match.
> 
> Greetings
> Hampus
> 
> 2017-11-03 2:10 GMT+01:00 Russell O'Connor via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org>:
>> Hi Jose,
>> 
>> Jets are briefly discussed in section 3.4 of https://blockstream.com/simplicity.pdf
>> 
>> The idea is that we can recognize some set of popular Simplicity expressions, and when the Simplicity interpreter encounters one of these expressions it can skip over the Simplicity interpreter and instead directly evaluate the function using specialized C or assembly code.
>> 
>> For example, when the Simplicity interpreter encounters the Simplicity expression for ECDSA verification, it might directly call into libsecp rather than continuing the ECDSA verification using interpreted Simplicity.
>> 
>> HTH.
>> 
>> 
>> On Nov 2, 2017 18:35, "JOSE FEMENIAS CAÑUELO via bitcoin-dev" <bitcoin-dev@lists•linuxfoundation.org> wrote:
>> Hi,
>> 
>> I am trying to follow this Simplicity proposal and I am seeing all over references to ‘jets’, but I haven’t been able to find any good reference to it.
>> Can anyone give me a brief explanation and or a link pointing to this feature?
>> Thanks
>> 
>>> On 31 Oct 2017, at 22:01, bitcoin-dev-request@lists•linuxfoundation.org wrote:
>>> 
>>> The plan is that discounted jets will be explicitly labeled as jets in the
>>> commitment.  If you can provide a Merkle path from the root to a node that
>>> is an explicit jet, but that jet isn't among the finite number of known
>>> discounted jets,
>> 
>> 
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>> 
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> 
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