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[2607:f8b0:4864:20::112f]) by gmr-mx.google.com with ESMTPS id d9443c01a7336-2b9cab4a2c8si3623605ad.6.2026.05.04.09.26.04 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 May 2026 09:26:04 -0700 (PDT) Received-SPF: pass (google.com: domain of tomh@thinlink.com designates 2607:f8b0:4864:20::112f as permitted sender) client-ip=2607:f8b0:4864:20::112f; Received: by mail-yw1-x112f.google.com with SMTP id 00721157ae682-7bd8cc5ad52so9500737b3.2 for ; Mon, 04 May 2026 09:26:04 -0700 (PDT) X-Gm-Gg: AeBDiesE7pbpTAmYYCwyhqwnknaHF6X7mgDBW41SnO830Kiaod740SkdxYCeuU7Cmjk O5aAn0lYP2T1TebCYPAwbT6H//SpkL166irtIuPcBEXaIRIGcAtokPi06JirSAswGbWgrYfpx3r aNeujXHBX0AhYN+btAAq9OplcnttZkjJV9D83CG1LKXcDE7aQgnGUHe4yqnMS3I53iSogNUXF52 alhFbkJTqgKmroBPgKJgXsTF87QxitwY3bjcaJCW2CRRJ3nQ4H6BMF8BmBAoGu/FSp8NIHKoQc4 BKlR2V24Kd4Pf+dUXjEdlK9KXAAHzXYKXhRsJQzu5OLv8VggsBa7OhlCOW7IIFC3WzvUgix/ccF ugRjatBjufPACsu1wZEXWY8BJmJvLrBmY/gfvdajWtWnlz5r7a1L5UIwiA1H9vi2X/2E3Mg7q54 lUUD4D3SeciiaqfqYc/QfdB5YTss7JXNwGQcCjyGGXDA== X-Received: by 2002:a05:690c:e347:b0:7bd:98c7:abcd with SMTP id 00721157ae682-7bd98c7afafmr34479637b3.38.1777911963059; Mon, 04 May 2026 09:26:03 -0700 (PDT) Received: from [192.168.1.230] ([99.8.65.117]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7bd66885907sm51835917b3.43.2026.05.04.09.26.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 May 2026 09:26:02 -0700 (PDT) Content-Type: multipart/alternative; boundary="------------PLZyYyeecy6FzPKeHZKHyTyU" Message-ID: <4516f3ab-0715-4dd9-825c-eed4eac3065a@thinlink.com> Date: Mon, 4 May 2026 09:26:00 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [bitcoindev] Re: Fly Client Proposal To: Zac Mitton Cc: Bitcoin Development Mailing List References: <0aadce7a-b08b-4fd2-8bae-37df1cfc54afn@googlegroups.com> Content-Language: en-US From: Tom Harding In-Reply-To: X-Original-Sender: tomh@thinlink.com X-Original-Authentication-Results: gmr-mx.google.com; dkim=pass header.i=@thinlink-com.20251104.gappssmtp.com header.s=20251104 header.b="XiuD/lQo"; spf=pass (google.com: domain of tomh@thinlink.com designates 2607:f8b0:4864:20::112f as permitted sender) smtp.mailfrom=tomh@thinlink.com; dara=pass header.i=@googlegroups.com Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.7 (/) This is a multi-part message in MIME format. --------------PLZyYyeecy6FzPKeHZKHyTyU Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: quoted-printable Zac, That's probably because the question, and my post, are off-topic.=C2=A0 The= y=20 are not about FlyClient, which is not interesting to me because=20 bitcoin's header chain is tiny. Instead they touch on two techniques which would improve on most=20 historical implementations of SPV clients by adding protocol support for=20 them. Sorry for the distraction. Tom On 5/3/26 12:26, Zac Mitton wrote: > Tom I can=E2=80=99t seem to grok the question or your explanation of it. = Could=20 > you spell it out for us in detail? > > > Thanks, Zac > > On Sun, May 3, 2026 at 12:58=E2=80=AFPM Tom Harding w= rote: > > In the linked presentation by Benedict B=C3=BCnz, it's worth listenin= g > to the first audience question/answer. Questioner is spot on that > an SPV client polling the network to gain probabilistic confidence > of unspentness could easily subsume the task of gaining input > inclusion proofs from the network, with no forking change necessary. > > On Wednesday, April 29, 2026 at 2:03:36=E2=80=AFPM UTC-7 Zac Mitton w= rote: > > Hi, Ive been looking into FlyClient first described here > . I don'= t > see any BIPs, or previous discussion in this forum about it > either. > > On bitcoin It could allow a light-client to verify the entire > work of the heaviest chain with a single ~100KB proof. > > It can theoretically be done as a soft-fork by injecting a > single hash into the coinbase tx (similar to how segwit is > committed to). > > What do you guy's think? > > --=20 You received this message because you are subscribed to the Google Groups "= Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoindev+unsubscribe@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/= 4516f3ab-0715-4dd9-825c-eed4eac3065a%40thinlink.com. --------------PLZyYyeecy6FzPKeHZKHyTyU Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

Zac,=C2=A0

That's probably because the question, and my post, are off-topic.=C2=A0 They are not about FlyClient, which is not interesti= ng to me because bitcoin's header chain is tiny.

Instead they touch on two techniques which would improve on most historical implementations of SPV clients by adding protocol support for them.

Sorry for the distraction.

Tom


On 5/3/26 12:26, Zac Mitton wrote:
Tom I can=E2=80=99t seem to grok the question or yo= ur explanation of it. Could you spell it out for us in detail?


Thanks, Zac

On Sun, May 3, 2026 at 12:58=E2=80=AFPM Tom Harding <tomh= @thinlink.com> wrote:
In the linked presentation by Benedict B=C3=BCnz, it's wor= th listening to the first audience question/answer.=C2=A0 Questioner is spot on that an SPV client polling the network to gain probabilistic confidence of unspentness could easily subsume the task of gaining input inclusion proofs from the network, with no forking change necessary.
On Wednesday, April 29= , 2026 at 2:03:36=E2=80=AFPM UTC-7 Zac Mitton wrote:
Hi, Ive been looking into FlyClient first described here. I don't see any BIPs, or previous discussion in this forum about it either.

On bitcoin It could allow a light-client to verify the entire work of the heaviest chain with a single ~100KB proof.

It can theoretically be done as a soft-fork by injecting a single hash into the coinbase tx (similar to how segwit is committed to).=C2=A0

What do you guy's think?

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