summaryrefslogtreecommitdiff
path: root/cd/1e09e21e9dbca5639580c3826374e1793eb9e9
blob: 632b7d11ac614f28a266105323a6ad922e617f68 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
Delivery-date: Mon, 09 Jun 2025 09:35:58 -0700
Received: from mail-oo1-f58.google.com ([209.85.161.58])
	by mail.fairlystable.org with esmtps  (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
	(Exim 4.94.2)
	(envelope-from <bitcoindev+bncBCL7RHHJZYJBBY42TTBAMGQEUAVSS4Y@googlegroups.com>)
	id 1uOfTY-00018p-J4
	for bitcoindev@gnusha.org; Mon, 09 Jun 2025 09:35:57 -0700
Received: by mail-oo1-f58.google.com with SMTP id 006d021491bc7-60eda518f7fsf1116121eaf.3
        for <bitcoindev@gnusha.org>; Mon, 09 Jun 2025 09:35:56 -0700 (PDT)
ARC-Seal: i=2; a=rsa-sha256; t=1749486951; cv=pass;
        d=google.com; s=arc-20240605;
        b=C25p86vsDrHuQXJTG3NXB//apzhwsiaUC8GvTRCz0bPmoFmblr347rB7ivofKxqJLJ
         fCa8zy7SC5wMaeNeSJkj2VpzlTiKIwIIJNZaWxwdByTwpghdwNi56ceFuL1TheAVmzUU
         QdWXMMQCzsFea8AwAYTLbDjQks5ZuPDX/Jm8ox4XRCabtLcwGc/Xdv23UtA0nPFfCy+o
         q8DtdeESRpCT4F1gb93TUb665KG/cq0cJ+7c8vI7AKyiC8TMuZQ7cCqP3ACvxShQoiXp
         1CWl1PRp+Hpi77jONIRvEzrZHj5P+VYsIK4cOj0uI64hcjNaMyXFclziCcHqx+KCGtSd
         6xNg==
ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:reply-to:mime-version:feedback-id
         :references:in-reply-to:message-id:subject:cc:from:to:date
         :dkim-signature;
        bh=vWQI/mbDV4tzsVUSlfOIhxOM9z2NmHbaFAPnm4GyfOQ=;
        fh=Ime58NJVfCOwUcLEbH8Ey47sub3GRJglfsCd3OySuUk=;
        b=iFh4HMlQiLq6/BQTcMOLT7XTQtGwRfxlTGnBppmj7/CTOuTLKY+M0ZkwUdgr9kdDf4
         c9x+ycdEYdpuqMHXA4UEn7mugtyYonz+Gm0qiwygtsSRI8fMeEn8Pr5XRAUikQ8e5JQK
         3XneIXlOJt6kEjsJtOY7bAXjMYvVgIsO6TTsUkMuisQzg5AzS/2ZBQyJAEprL0WBfIKN
         UO5AERu5LHKeUeQQqafs89DvmGoEIfcxZQyJrajett7h22+D0c2XYE6D9Wkvjbss3Jjv
         xzdFhO6dFV4KV2vJq+UOeymqZxTykyA2PO9H5Y3zB8j+qd62IQN55az8Q7kp4ZErafYu
         TX9g==;
        darn=gnusha.org
ARC-Authentication-Results: i=2; gmr-mx.google.com;
       dkim=pass header.i=@proton.me header.s=protonmail header.b=KPilypuU;
       spf=pass (google.com: domain of conduition@proton.me designates 109.224.244.18 as permitted sender) smtp.mailfrom=conduition@proton.me;
       dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=proton.me
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=googlegroups.com; s=20230601; t=1749486951; x=1750091751; darn=gnusha.org;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:reply-to
         :x-original-authentication-results:x-original-sender:mime-version
         :feedback-id:references:in-reply-to:message-id:subject:cc:from:to
         :date:from:to:cc:subject:date:message-id:reply-to;
        bh=vWQI/mbDV4tzsVUSlfOIhxOM9z2NmHbaFAPnm4GyfOQ=;
        b=x2m7dlG5HRigCzFuuvwLbIfh0C62JXM6gTyjcJQ6WdlCJkuI3RoxtiDSaTpDE+U4vT
         iZg7eraIKz/2KnTSqJ6KocMGJhCCnSi4izIY/ZRXahgtWozThDjVX0Pe24QE7ibsuknc
         K7qbCJRpxaNS8Ir5wbcta0cV5QvuBL+O+HIyHvYqfmAXw6pblbcELVTTFbE0TbukW20i
         csEgN3oc/FzK47OnzAoD8BUirjXHHTa77DCqIuAliEIh2hKiaa5UUguhWbZcJ1QRCbiv
         qDaNZSwlvh0IQ6WJjcbcSkoivwJsOLtl8y2yj75nD3WC+eDRUCONE5We5ONRL45KmHZY
         MVHA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20230601; t=1749486951; x=1750091751;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:reply-to
         :x-original-authentication-results:x-original-sender:mime-version
         :feedback-id:references:in-reply-to:message-id:subject:cc:from:to
         :date:x-beenthere:x-gm-message-state:from:to:cc:subject:date
         :message-id:reply-to;
        bh=vWQI/mbDV4tzsVUSlfOIhxOM9z2NmHbaFAPnm4GyfOQ=;
        b=Uga154/h1Bd2xPmJc+rHOFIoujiaasVj0lgGJ1stu/bobcabDn27lBGcLs1yl7mzyL
         V1J+XHCu05cCL7mTZ1e/jAfpvCIrcfsBLXNo6vYPEqhJVDQmTco2oigQzIesHiGtaHPq
         UpxM79fRIj8NYL4r4SEy4o/qHtxRkGex3LNTu8xUGkRaMJbOSDe4j09C175IHxIiv9+C
         Ou2fBbmy/tKg5dZqm3F3pCdjfsKEiEbjKURDewDjgZorFrf51aY8s/7UHz9hV2SFbQlH
         BSoyEyFPXGYGFHGWyJaQZJ8fOfyXfWl4wigWEvCgJtzkC/MeE3KHxxv3X1Z6lwfGlDJP
         hHhA==
X-Forwarded-Encrypted: i=2; AJvYcCVYf8/elHQC0wRz5l7vD70pt7wqgjFTW3uloKfBJxbermXq50OKGMafqlj41RuZaQiRYOKe0sONXwJ1@gnusha.org
X-Gm-Message-State: AOJu0YyeF9n+50wYcqpw1Lv7H2sBPNkC4D/kV7ZPkrLf89lzJ2oopvZH
	24vD05wPtBva4SRPeT4+uH40Qqkd6Ux2tBaMZ/6K16qWDTek0o3szULH
X-Google-Smtp-Source: AGHT+IEJicVnHZXPSbSB01i+EpALZApFQFho/iHf/rinB24sZsaULRQA+rgijPSdxOGT5EOBI1u6hQ==
X-Received: by 2002:a4a:a607:0:b0:60f:484e:720e with SMTP id 006d021491bc7-60f484e7b9bmr5696701eaf.6.1749486950834;
        Mon, 09 Jun 2025 09:35:50 -0700 (PDT)
X-BeenThere: bitcoindev@googlegroups.com; h=AZMbMZdhWPy6LMiBXzFlkG7tyDmQdibWIAz0Stk5bA/dZ8a6Ug==
Received: by 2002:a4a:a507:0:b0:60f:195e:84fc with SMTP id 006d021491bc7-60f28336becls422461eaf.0.-pod-prod-04-us;
 Mon, 09 Jun 2025 09:35:47 -0700 (PDT)
X-Received: by 2002:a05:6808:308e:b0:401:ea7b:e535 with SMTP id 5614622812f47-409051fae2amr8485758b6e.22.1749486947366;
        Mon, 09 Jun 2025 09:35:47 -0700 (PDT)
Received: by 2002:a05:6808:83:b0:3f6:a384:eb6f with SMTP id 5614622812f47-40905e8baf2msb6e;
        Mon, 9 Jun 2025 09:29:55 -0700 (PDT)
X-Received: by 2002:a05:6830:6103:b0:72b:a196:5221 with SMTP id 46e09a7af769-73888dbf535mr11827655a34.8.1749486593694;
        Mon, 09 Jun 2025 09:29:53 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1749486593; cv=none;
        d=google.com; s=arc-20240605;
        b=QP5gEu1u7NzzzcqqAlwtJOczFeFSN4cw4zoRoI1KhfXQcNQcKq7etoKOE5rHeFOvph
         YKO+66ePYbmmhPO7nE3gsKQaPrcMr1XNi41qijxTmAum/P/fQCeXqfXJveEXFGJWsQ2Q
         QwruMBwH5oMRAlXYtEQuqIYeEQcSc24C1rq97m8N9jfggJR2Zzcvs6GiBn1xAzMc9bLl
         XaGe+Mo/QYm10e2LrX5XeyvdjGMQiY4mnZgAzCmgxR3OPaPTj30vMrL+iuqHeDpJSqLL
         OzKB5wllS4Um9X9dez66MolqUD8uRyFg7Lung4jjiATNfjcuujLLd8BtelCcQRidgirf
         J3fA==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605;
        h=mime-version:feedback-id:references:in-reply-to:message-id:subject
         :cc:from:to:date:dkim-signature;
        bh=3RHHnPfesSOiKMqZkkTpS4Pb9QyC9Z3jkIlXS33PM7U=;
        fh=e79b22hAuSaC6/8oKXuBX7NFmH7iXgOLPA7D5tCVfno=;
        b=G5Rcj207KRByFSjR931MwAul5f8yaugbYSIqrbHWMeaOctNfFK4EvnOmIytaLHyYJw
         1mTGru7BTveY/86k4xTjWKA6RlSwMiu88xdzSkhy3q5B420omamg1ECSYcnj4Op4GmcX
         H2dhDZvFS4Pg5tnP0WgkxXAdJHYw/HMluCXkRkERcJHrg6nhdDMryOZudUIPECsG7qTE
         yABi/hJLzTGqlpEEf6T3CqySuF32r1oF1CHp6fZ+MbbGwJwDB2+ohRWJwuMfDQHlvR0i
         yn0DEUzEgxGK7uTsnWoBZWHyukx4uVMg4Hdm0g4pRDHlmVUYnP+Y2LZ6bgAzMuwrY0Vw
         0GRw==;
        dara=google.com
ARC-Authentication-Results: i=1; gmr-mx.google.com;
       dkim=pass header.i=@proton.me header.s=protonmail header.b=KPilypuU;
       spf=pass (google.com: domain of conduition@proton.me designates 109.224.244.18 as permitted sender) smtp.mailfrom=conduition@proton.me;
       dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=proton.me
Received: from mail-24418.protonmail.ch (mail-24418.protonmail.ch. [109.224.244.18])
        by gmr-mx.google.com with ESMTPS id 46e09a7af769-7388a0601e5si364139a34.4.2025.06.09.09.29.53
        for <bitcoindev@googlegroups.com>
        (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);
        Mon, 09 Jun 2025 09:29:53 -0700 (PDT)
Received-SPF: pass (google.com: domain of conduition@proton.me designates 109.224.244.18 as permitted sender) client-ip=109.224.244.18;
Date: Mon, 09 Jun 2025 16:29:48 +0000
To: Leo Wandersleb <lwandersleb@gmail.com>
From: "'conduition' via Bitcoin Development Mailing List" <bitcoindev@googlegroups.com>
Cc: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] Pre-emptive commit/reveal for quantum-safe migration (poison-pill)
Message-ID: <ejSZyf9UmYgOm9D40yAcKNk03pKBLk82dAmdgjq0xNGRZK4R2jd0DcbZqiXoSiYNBBzMpGcezGwTe3wLN96VCl7R0yqPbChWlsKWTphUqUw=@proton.me>
In-Reply-To: <d6196c29-267f-4172-8b39-9e2abd344378n@googlegroups.com>
References: <2c3b7e1c-95dd-4773-a88f-f2cdb37acf4a@gmail.com> <ZmYpRwmVDoJBUhiCRb909Lgwws_dT9d_CNUjfddVt128pyjdH0UcYfXgA_uguwRu44ZC8_x_SwlrooqKhyvdwJjnO1h3BvzQxVRbdCpVfjg=@proton.me> <5e393f57-ac87-40fd-93ef-e1006accdb55n@googlegroups.com> <CAFC_Vt5X2qrH9EaZNoMMx8367V7iYfXiCcAfT3ED86DtM7UH6A@mail.gmail.com> <5d9f6ac9-a623-4636-8a91-ee7c057bc08an@googlegroups.com> <44b5aa4c-a71b-49ed-beee-071140b16aacn@googlegroups.com> <ea71bbd5-1325-445b-977f-a52b8017eab4n@googlegroups.com> <dupr0g-yupBxLl70WyuEcfAIt1DNXZDY6Z_RuhZsKwAQro1aONB8IIWcsAjytBQjsDmlXsoDjBNI5KEaMqfzqIWLvrXY60gLKxy4n9wKzQg=@proton.me> <d6196c29-267f-4172-8b39-9e2abd344378n@googlegroups.com>
Feedback-ID: 72003692:user:proton
X-Pm-Message-ID: 96b346e8fda5cdc89fa2b47831d4c7c7ab84b91e
MIME-Version: 1.0
Content-Type: multipart/signed; protocol="application/pgp-signature"; micalg=pgp-sha512; boundary="------16df4ee7c96e2752135d0dd361c89c63b2ce9dcf7b11badfb227a0b271c85644"; charset=utf-8
X-Original-Sender: conduition@proton.me
X-Original-Authentication-Results: gmr-mx.google.com;       dkim=pass
 header.i=@proton.me header.s=protonmail header.b=KPilypuU;       spf=pass
 (google.com: domain of conduition@proton.me designates 109.224.244.18 as
 permitted sender) smtp.mailfrom=conduition@proton.me;       dmarc=pass
 (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=proton.me
X-Original-From: conduition <conduition@proton.me>
Reply-To: conduition <conduition@proton.me>
Precedence: list
Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com
List-ID: <bitcoindev.googlegroups.com>
X-Google-Group-Id: 786775582512
List-Post: <https://groups.google.com/group/bitcoindev/post>, <mailto:bitcoindev@googlegroups.com>
List-Help: <https://groups.google.com/support/>, <mailto:bitcoindev+help@googlegroups.com>
List-Archive: <https://groups.google.com/group/bitcoindev
List-Subscribe: <https://groups.google.com/group/bitcoindev/subscribe>, <mailto:bitcoindev+subscribe@googlegroups.com>
List-Unsubscribe: <mailto:googlegroups-manage+786775582512+unsubscribe@googlegroups.com>,
 <https://groups.google.com/group/bitcoindev/subscribe>
X-Spam-Score: -1.0 (-)

This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
--------16df4ee7c96e2752135d0dd361c89c63b2ce9dcf7b11badfb227a0b271c85644
Content-Type: multipart/mixed;boundary=---------------------6bf10faa39e1068402aa89991cf0d928

-----------------------6bf10faa39e1068402aa89991cf0d928
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset="UTF-8"

Thanks for clarifying, Leo, that does make a bit more
sense now.

I'm not in love with the duplication of TX data
on-chain, but it could technically be workable.=C2=A0

Possible improvement: instead of committing to the
wTXID and revealing the entire transaction, maybe
reveal only the wTXID at step 3. After all, you're not
mining the TX yet, just initiating a challenge phase
to see which is the oldest committed spending TX.
The actual spending TX data is not necessary at this stage
unless you want the TX to be automatically published
(by being stored on-chain already).

Either way this would be quite complicated to implement.
Nodes would have to maintain a DB which tracks the info
needed to validate these new spending rules.

I think i still prefer Martin's commit/reveal solution
[0] better for a few reasons.=C2=A0

1. It doesn't require nodes keep track of commitments,
   reveals, and counter-reveals independently of the UTXO
   set.
2. It's more space efficient.
3. It requires no convoluted "counter reveal" stage.

I realize your announcement-based approach could, in
theory, protect exposed pubkeys, but I see a bit of a
problem there. For an exposed pubkey to be protected
with this commit/reveal protocol, its owner must

- sign a TX which spends all the UTXOs in the exposed
  pubkey address
- commit to that TX in an on-chain announcement TX
  (e.g.=C2=A0via OP_RETURN)
- repeat and publish a new announcement any time the
  UTXOs in the address change
- do all of this before=C2=A0a quantum attacker inverts
  their pubkey and publishes their own announcement

If the user has the ability and awareness to actively
prepare for Q-day like this, why wouldn't they simply
move their funds to a quantum safe address? Or lacking
that, even just to a hashed address without an exposed
pubkey, from which they'd stand a better chance to evade
quantum attack?

I think the real problem with exposed-pubkey addresses
is for cases where the owners are offline, unaware,
unable, or unwilling to make quantum preparations.
Without active preparation, i suspect exposed-pubkey
addresses are lost causes. (happy to be proven wrong though)

regards,
conduition


[0]:=C2=A0https://groups.google.com/g/bitcoindev/c/jr1QO95k6Uc/m/2UDYJ-z6Ag=
AJ


On Monday, June 9th, 2025 at 6:10 AM, Leo Wandersleb <lwandersleb@gmail.com=
> wrote:

> Hi conduition,
> I see the confusion - let me clarify step 3:
>=20

> The "reveal" is an on-chain announcement that includes the full transacti=
on data, but it's not executed as a spending transaction yet. Think of it a=
s:
>=20

> ```
> Block N: Announcement TX containing:
> - Full spending transaction (with signatures, witness data)
> - Merkle proof linking to prior commitment
> - Reference to target UTXO
> ```
>=20

> This announcement transaction gets mined immediately (paying fees with ot=
her inputs), but the vulnerable UTXO remains unspent. It's essentially stor=
ing the transaction data on-chain for the contest period.
>=20

> After 144 blocks, the winning transaction (oldest valid commitment) can b=
e executed as a normal spend. No double-spending or special states needed -=
 the UTXO simply can't be spent until the contest period ends and we know w=
hich commitment won.
>=20

> So yes, we're storing the transaction data twice (once in announcement, o=
nce in actual execution), but this avoids any consensus-breaking changes wh=
ile protecting against quantum attacks.
>=20

> Regards,
>=20

> Leo
>=20

> ---
> On Thursday, 5 June 2025 at 17:10:46 UTC+2 conduition wrote:
>=20

> > Hi Leo,
> >=20

> > When a user reveals a transaction + commitment proof, are you
> > assuming it will be included in a block? Or is the reveal TX
> > somehow put "on ice" for those 144 blocks, and only then mined?
> >=20

> >=20

> > If the former, this implies your protocol would need to allow
> > double-spending of UTXOs even after many confirmations, as
> > Tim has noted. Otherwise having an older announcement wouldn't
> > give any advantage. I don't see how you'd implement this without
> > breaking many founding assumptions of Bitcoin, maybe introducing
> > some new special "confirmed-but-pending" state specifically
> > for the outputs of these reveal TXs.
> >=20

> > If the latter, and the TX isn't immediately mineable, then how
> > exactly do nodes know when to consider it consensus-valid?
> > Imagine you're a node and you receive a reveal transaction
> > with a valid (old enough) commitment proof. The TX claims
> > to have been created 144 blocks ago and thus should be
> > mineable. But how do you verify that, if the TX wasn't
> > included in a past block?
> >=20

> > regards,
> > conduition
> >=20

> > On Thursday, June 5th, 2025 at 7:55 AM, Leo Wandersleb <lwand...@gmail.=
com> wrote:
> >=20

> > > Hi Boris, hi list,
> > > I think the weak announcement is a bad idea once EC crypto is broken =
to the point where an attacker can break the key before the transaction get=
s mined but the strong announcements should still hold as they have less ur=
gency. If the attacker sees the transaction in a strong announcement with a=
 full transaction, he cannot win even if he gets into a block first, as the=
 strong announcement proves a prior commitment to that transaction and woul=
d win even if it gets mined only some blocks later.
> > >
> >=20

> > > A scheme where the announcement does not contain the full transaction=
 is problematic as the transaction might then turn out to not be valid. The=
n nodes would wait for the "winning" wtxid blocking the UTXO forever.
> > >
> >=20

> > > So the scheme is:
> > >
> >=20

> > > After activation at block height X:
> > >
> >=20

> > > 1. **Vulnerable UTXOs cannot be spent directly** - they require a pri=
or announcement
> > > 2. **Commitment** to a wTXID that spends the vulnerable UTXO. Multipl=
e wTXIDs can be stored in a hash tree in an OP_RETURN
> > > 3. **Reveal** full transaction with proof of prior commitment but not=
 as a normal transaction yet
> > > 4. **Counter Reveal**: For 144 blocks, others can reveal older commit=
ments. This protects exposed pubkeys!
> > > 5. **After 144 blocks**: The UTXO can be spent according to the stron=
gest announcement (oldest commitment of valid transaction wins).
> > >
> >=20

> > > As (5) is just the normal transaction, the scheme is a soft fork and =
compatible with pre-recorded transactions where the keys were lost. It woul=
d at least double the on-chain costs for these vulnerable UTXOs as they wou=
ld have to store the full transaction twice. We can make the announcements =
prunable again though.
> > >
> >=20

> > > Best,
> > >
> >=20

> > > Leo
> > > On Wednesday, 4 June 2025 at 20:40:32 UTC+2 Boris Nagaev wrote:
> > >
> >=20

> > > > Hi Leo,
> > > >
> >=20

> > > > I think it is possible to provide privacy for Satoshi and also redu=
ce the size of a weak announcement (strong announcements can already be sma=
ll: just a txid or a Merkle root of many txids).
> > > >
> >=20

> > > > Importantly, we cannot include the whole signed transaction in the =
weak announcement. Doing so would leak the EC public key immediately, allow=
ing an attacker to create their own valid weak announcement. We must avoid =
revealing the public key until the actual spending transaction is broadcast=
.
> > > >
> >=20

> > > > We need a scheme where the EC public key is not leaked in a weak an=
nouncement, but the legitimate owner can verify it, while no one else can. =
Also, once the EC public key is revealed, anyone should be able to verify a=
 past weak announcement (to validate the transaction when it is broadcast).=
 This reduces to the following requirement: we need a proof of knowledge of=
 the EC public key that can be verified if the public key is known and prov=
ides no information otherwise.
> > > >
> >=20

> > > > I think this is called a zero-knowledge proof. One simple approach =
could be to apply a tagged hash function to the concatenation of the EC pub=
lic key and the future wTXID, and include this in the weak announcement. Th=
e structure would be:
> > > >
> >=20

> > > > - UTXO (previous TXID and output index)
> > > > - future spending wTXID
> > > > - proof :=3D tagged_hash(EC public key || wTXID)
> > > >
> >=20

> > > > The wTXID is included in the concatenation to bind the proof to a p=
articular future transaction. Otherwise, someone could copy a weak announce=
ment and substitute their own wTXID.
> > > >
> >=20

> > > > Satoshi could publish a strong announcement now and then monitor al=
l weak announcements involving his UTXOs. If someone publishes a weak annou=
ncement for one of his coins, he could verify the "proof" field. If it is v=
alid, it would mean someone has cracked his key with a quantum computer, an=
d he would need to use his strong announcement immediately to reclaim the f=
unds before the attacker does.
> > > >
> >=20

> > > > Best,
> > > > Boris
> > > >
> >=20

> > > > On Wednesday, June 4, 2025 at 2:40:53=E2=80=AFPM UTC-3 Leo Wandersl=
eb wrote:
> > > >
> >=20

> > > > > Hi Boris,
> > > > > the announcements, weak and strong would have to not be transacti=
ons yet to be compatible with legacy nodes and thus keep it a soft-fork. Th=
ey could be OP_RETURN data. Only after the 144 blocks, the upgraded full no=
des would allow the inclusion of the actual transaction. This would mean th=
e transaction would be both in full in the OP_RETURN strong announcement an=
d without the witness part later, so it would be a bit expensive this way b=
ut maybe we can do better?
> > > > >
> >=20

> > > > > A node that gets updated would have to re-index all the blockchai=
n to find announcements if we don't introduce a time frame for actually usi=
ng the announcements. We could also say that any announcement has to be use=
d within another 1000 blocks. Then the upgrading node would have to re-inde=
x the last 1000 blocks.
> > > > >
> >=20

> > > > > The legitimate owner of a UTXO might wait for an attack for priva=
cy reasons. My proposal would allow Satoshi himself to make all his UTXOs q=
uantum safe without any of us learning about him being active. He could add=
 one 64B OP_RETURN in 2027 and when QC becomes an issue, we would learn abo=
ut him having been active in 2027 in 2040 when actually somebody tried to a=
ttack and not in 2027 when people started to panic because of imminent quan=
tum breakthroughs.
> > > > > Hmm ... a problem is the weak announcement doesn't require keys, =
so anybody could provoke Satoshi to come forward. Maybe we have to add key =
ownership as a requirement for the "weak" announcement, too. So it should a=
lso contain a serialized transaction.
> > > > >
> >=20

> > > > > Best,
> > > > >
> >=20

> > > > > Leo
> > > > >
> >=20

> > > > > On Wednesday, 4 June 2025 at 04:15:59 UTC+2 Nagaev Boris wrote:
> > > > >
> >=20

> > > > > > Hi Leo,
> > > > > >
> >=20

> > > > > > Thanks for the clarifications, much appreciated!
> > > > > > I have a couple of questions:
> > > > > >
> >=20

> > > > > > 1. How is a weak announcement stored in the blockchain and in t=
he UTXO set?
> > > > > > I assume it must be a transaction, correct? And it should someh=
ow mark
> > > > > > the UTXO as planned to be spent for 144 blocks?
> > > > > > How would older (non-upgraded) nodes interpret a transaction
> > > > > > containing a weak announcement? Would they just skip over it wi=
thout
> > > > > > any special processing?
> > > > > > If so, is there a problem for nodes that upgrade after the fork=
: would
> > > > > > they have to reprocess all blocks since the fork to find and in=
dex all
> > > > > > missed weak announcements?
> > > > > >
> >=20

> > > > > > 2. In the case of reclaiming a UTXO after a weak announcement b=
y an
> > > > > > attacker: why would the legitimate owner wait for a weak announ=
cement
> > > > > > at all?
> > > > > > If the EC public key was already leaked, it seems they should p=
ublish
> > > > > > a strong announcement themselves rather than wait. If the EC pu=
blic
> > > > > > key wasn't leaked, there's nothing to worry about even if someo=
ne
> > > > > > publishes a weak announcement: they are most likely bluffing, s=
ince
> > > > > > they wouldn't have the actual public key.
> > > > > >
> >=20

> > > > > > Best,
> > > > > > Boris
> > > > > >
> >=20

> > > > > > On Tue, Jun 3, 2025 at 3:29=E2=80=AFPM Leo Wandersleb <lwand...=
@gmail.com> wrote:
> > > > > > >
> > > > > > > Hi conduition,
> > > > > > >
> > > > > > > Thanks for your careful analysis - excellent catches.
> > > > > > >
> > > > > > > You're absolutely right about the txid vulnerability. The com=
mitment must be to the complete transaction including witness data (wTXID o=
r equivalent) to prevent an attacker from pre-committing to unsigned transa=
ctions. This is essential - otherwise an attacker could indeed enumerate th=
e UTXO set and create commitments without knowing the private keys.
> > > > > > >
> > > > > > > Regarding updates: You're correct that frequent updates would=
 be needed as wallets receive new UTXOs. However, I don't see this as a maj=
or issue - users could batch their commitments periodically (say, monthly) =
rather than after every transaction. The scheme is particularly important f=
or existing UTXOs that already have exposed pubkeys (old P2PK, reused addre=
sses, etc.). For new UTXOs, wallets should ideally migrate to quantum-safe =
addresses once available. OpenTimestamps aggregation would indeed help with=
 scaling and provide plausible deniability about the number of UTXOs being =
protected.
> > > > > > >
> > > > > > > The time delay serves a different purpose than you might expe=
ct. It's not about preventing commitment forgery after pubkey exposure, but=
 rather about allowing priority based on commitment age when multiple parti=
es claim the same UTXO:
> > > > > > >
> > > > > > > 1. Weak announcement starts the 144-block window
> > > > > > > 2. During this window, anyone with a strong commitment can re=
veal it
> > > > > > > 3. The oldest valid commitment wins
> > > > > > >
> > > > > > > This creates the "poison pill" effect: an attacker might crac=
k a key and try to spend a UTXO, but if the original owner has an older com=
mitment, they can reclaim it during the window. The uncertainty about which=
 UTXOs have poison pills makes attacking large "lost" UTXOs risky - hence l=
ess disruptive to the network.
> > > > > > >
> > > > > > > The delay essentially allows a "commitment priority contest" =
where age determines the winner, protecting users who prepared early while =
still allowing these users to not move their funds.
> > > > > > >
> > > > > > > Best,
> > > > > > >
> > > > > > > Leo
> > > > > > >
> > > > > > > --
> > > > > > > You received this message because you are subscribed to the G=
oogle Groups "Bitcoin Development Mailing List" group.
> > > > > > > To unsubscribe from this group and stop receiving emails from=
 it, send an email to bitcoindev+...@googlegroups.com.
> > > > > > > To view this discussion visit https://groups.google.com/d/msg=
id/bitcoindev/5e393f57-ac87-40fd-93ef-e1006accdb55n%40googlegroups.com.
> > > > > >
> >=20

> > > > > >
> >=20

> > > > > >
> >=20

> > > > > > --
> > > > > > Best regards,
> > > > > > Boris Nagaev
> > >
> >=20

> > > --
> > > You received this message because you are subscribed to the Google Gr=
oups "Bitcoin Development Mailing List" group.
> > > To unsubscribe from this group and stop receiving emails from it, sen=
d an email to bitcoindev+...@googlegroups.com.
> > > To view this discussion visit https://groups.google.com/d/msgid/bitco=
indev/ea71bbd5-1325-445b-977f-a52b8017eab4n%40googlegroups.com.
>=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=
 email to bitcoindev+unsubscribe@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/bitcoinde=
v/d6196c29-267f-4172-8b39-9e2abd344378n%40googlegroups.com.

--=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/=
ejSZyf9UmYgOm9D40yAcKNk03pKBLk82dAmdgjq0xNGRZK4R2jd0DcbZqiXoSiYNBBzMpGcezGw=
Te3wLN96VCl7R0yqPbChWlsKWTphUqUw%3D%40proton.me.

-----------------------6bf10faa39e1068402aa89991cf0d928
Content-Type: application/pgp-keys; filename="publickey - conduition@proton.me - 0x474891AD.asc"; name="publickey - conduition@proton.me - 0x474891AD.asc"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="publickey - conduition@proton.me - 0x474891AD.asc"; name="publickey - conduition@proton.me - 0x474891AD.asc"
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-----------------------6bf10faa39e1068402aa89991cf0d928--

--------16df4ee7c96e2752135d0dd361c89c63b2ce9dcf7b11badfb227a0b271c85644
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: ProtonMail

wrsEARYKAG0FgmhHC+sJkHgpbO2E9rPFRRQAAAAAABwAIHNhbHRAbm90YXRp
b25zLm9wZW5wZ3Bqcy5vcme2kuJfhDVna/IYaGeSqW3WQm4Ayn6qyhZwIfA5
BW7QhBYhBEdIka0CMtrLdg13a3gpbO2E9rPFAABpyAEA7x7C7HdWiRpqKnxj
4ulG3kj4kTE8ohUBu+1pQSQtBtIA/3LH5FbNu4Vzwf8nEP0RnHfHgPtvZ/18
30dR+HW+1PQB
=6BRq
-----END PGP SIGNATURE-----


--------16df4ee7c96e2752135d0dd361c89c63b2ce9dcf7b11badfb227a0b271c85644--