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
|
Received: from sog-mx-3.v43.ch3.sourceforge.com ([172.29.43.193]
helo=mx.sourceforge.net)
by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
(envelope-from <jtimon@jtimon.cc>) id 1YmKqc-0000XG-9j
for bitcoin-development@lists.sourceforge.net;
Sun, 26 Apr 2015 11:35:42 +0000
Received: from mail-wi0-f177.google.com ([209.85.212.177])
by sog-mx-3.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128)
(Exim 4.76) id 1YmKqZ-0005HR-UU
for bitcoin-development@lists.sourceforge.net;
Sun, 26 Apr 2015 11:35:42 +0000
Received: by wicmx19 with SMTP id mx19so64298920wic.1
for <bitcoin-development@lists.sourceforge.net>;
Sun, 26 Apr 2015 04:35:33 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20130820;
h=x-gm-message-state:mime-version:in-reply-to:references:date
:message-id:subject:from:to:cc:content-type;
bh=VsvLhQXYTuuvfJ4kA0hwry7nU2B+jPALJoHwB/fSMvE=;
b=artD8JYAtYAMmhvbRSdLYMTQ6txFLmeYqddq/YTXlhkjZYmtKD5YeuvY4ZYkTxWKbi
dkime2vQdRNs5XUz6ZsHL+wC++Y6mAl/LNvjDFuok68cfx2Y1lKmaqciBygexcDt3jcx
Bv9izdbu+n7NNXzCmhQUwVUYmHeSqexMAokpjawMkv+hnEYVhdBQjWlpnFtGxRxvWJjR
m96yjjzAAI9pHTrGKSgWGlpVlPzeWwFesW6IyJlXtssDbTk0nf3WanvX7652QqASR205
KNRaiDZpBTu5bslFTI1uPXou30gT54xMa/I8+0d1UTWtfS3OYiQbrk94jviNPcnvNtVF
agfw==
X-Gm-Message-State: ALoCoQnehoGBvROEd1Mwy896U31Nt7YQ/Jx3+9lH6ULiL7j1kRloetmdKIhYuvk2pT9tmEh73cS7
MIME-Version: 1.0
X-Received: by 10.180.37.73 with SMTP id w9mr12031409wij.7.1430048133662; Sun,
26 Apr 2015 04:35:33 -0700 (PDT)
Received: by 10.194.124.2 with HTTP; Sun, 26 Apr 2015 04:35:33 -0700 (PDT)
In-Reply-To: <20150421075912.GA25282@savin.petertodd.org>
References: <20141001130826.GM28710@savin.petertodd.org>
<55075795.20904@bluematt.me>
<20150421075912.GA25282@savin.petertodd.org>
Date: Sun, 26 Apr 2015 13:35:33 +0200
Message-ID: <CABm2gDo22grffq4j+Jy_HBD-VrROh32Dbseoa=g-5HXA9Uud1w@mail.gmail.com>
From: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= <jtimon@jtimon.cc>
To: Peter Todd <pete@petertodd.org>
Content-Type: text/plain; charset=UTF-8
X-Spam-Score: 0.0 (/)
X-Spam-Report: Spam Filtering performed by mx.sourceforge.net.
See http://spamassassin.org/tag/ for more details.
X-Headers-End: 1YmKqZ-0005HR-UU
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Relative CHECKLOCKTIMEVERIFY (was CLTV
proposal)
X-BeenThere: bitcoin-development@lists.sourceforge.net
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: <bitcoin-development.lists.sourceforge.net>
List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=bitcoin-development>
List-Post: <mailto:bitcoin-development@lists.sourceforge.net>
List-Help: <mailto:bitcoin-development-request@lists.sourceforge.net?subject=help>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=subscribe>
X-List-Received-Date: Sun, 26 Apr 2015 11:35:42 -0000
On Tue, Apr 21, 2015 at 9:59 AM, Peter Todd <pete@petertodd.org> wrote:
> Thus we have a few possibilities:
>
> 1) RCLTV against nLockTime
>
> Needs a minimum age > COINBASE_MATURITY to be safe.
>
>
> 2) RCLTV against current block height/time
>
> Completely reorg safe.
Yes, can we call this one OP_MATURITY to distinguish it from RCLTV?
> 3) GET_TXOUT_HEIGHT/TIME <diff> ADD CLTV
>
> To be reorg safe GET_TXOUT_HEIGHT/TIME must fail if minimum age <
> COINBASE_MATURITY. This can be implemented by comparing against
> nLockTime.
Mhmm, interesting.
> All three possibilities require us to make information about the
> prevout's height/time available to VerifyScript(). The only question is
> if we want VerifyScript() to also take the current block height/time - I
> see no reason why it can't. As for the mempool, keeping track of what
> transactions made use of these opcodes so they can be reevaluated if
> their prevouts are re-organised seems fine to me.
I'm totally fine with changing the interface to:
int bitcoinconsensus_verify_script(const unsigned char
*scriptPubKey, unsigned int scriptPubKeyLen,
const unsigned char *txTo
, unsigned int txToLen, unsigned nHeight,
unsigned int nIn, unsigned int
flags, bitcoinconsensus_error* err);
I prefer op_maturity over RCLTV and there are also gains for absolute
CLTV as you explain later.
When you validate the script inputs of a transaction you already have
a height, either the real final nHeight in ConnectBlock and the miner,
or nSpendHeight in AcceptToMemoryPool.
The costs are meaningless in my opinion, specially when we will
already have to change the interface to add libsecp256k1's context.
I'm infinitely more worried about the other assumption that the 3
solutions are already making.
Changing to
int bitcoinconsensus_verify_script(const unsigned char
*scriptPubKey, unsigned int scriptPubKeyLen,
const unsigned char *txTo
, unsigned int txToLen, const CCoinsViewCache& inputs,
unsigned int nIn, unsigned int
flags, bitcoinconsensus_error* err);
Is simply not possible because CCoinsViewCache is a C++.
You could solve it in a similar way in which you could solve that
dependency for VerifyTransaction.
For example:
typedef const CTxOut& (*TxOutputGetter)(const uint256& txid, uint32_t n);
int bitcoinconsensus_verify_script(const unsigned char
*scriptPubKey, unsigned int scriptPubKeyLen,
const unsigned char *txTo
, unsigned int txToLen, TxOutputGetter utxoGetter,
unsigned int nIn, unsigned int
flags, bitcoinconsensus_error* err);
Of course, this is assuming that CTxOut becomes a C struct instead of
a C++ class and little things like that.
In terms of code encapsulation, this is still 100 times uglier than
adding the nHeight so if we're doing it, yes, please, let's do both.
There's another possibility that could keep the utxo out of Script verification:
class CTxIn
{
public:
COutPoint prevout;
CScript scriptSig;
uint32_t nSequence;
}
could turn into:
class CTxIn
{
public:
COutPoint prevout;
CScript scriptSig;
uint32_t nHeight;
}
And a new softfork rule could enforce that all new CTxIn set nHeight
to the correct height in which its corresponding prevout got into the
chain.
That would remove the need for the TxOutputGetter param in
bitcoinconsensus_verify_script, but unfortunately it is not reorg safe
(apart from other ugly implementation details).
So, in summary, I think the new interface has to be something along these lines:
int bitcoinconsensus_verify_script(const unsigned char
*scriptPubKey, unsigned int scriptPubKeyLen,
const unsigned char *txTo,
unsigned int nIn,
unsigned int txToLen,
TxOutputGetter utxoGetter, unsigned nHeight, secp256k1_context_t *ctx
unsigned int flags,
bitcoinconsensus_error* err);
> Time-based locks
> ================
>
> Do we want to support them at all? May cause incentive issues with
> mining, see #bitcoin-wizards discussion, Jul 17th 2013:
>
> https://download.wpsoftware.net/bitcoin/wizards/2013/07/13-07-17.log
I'm totally fine not supporting time-based locks for the new operators.
Removing them from the regular nLockTime could be more complicated but
I wouldn't mind either.
Every time I think of a contract or protocol that involves time, I do
it in terms of block heights.
I would prefer to change all my clocks to work in blocks instead of
minutes over changing nHeights for timestamps in any of those
contracts.
> --
> 'peter'[:-1]@petertodd.org
> 0000000000000000015e09479548c5b63b99a62d31b019e6479f195bf0cbd935
>
> ------------------------------------------------------------------------------
> BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT
> Develop your own process in accordance with the BPMN 2 standard
> Learn Process modeling best practices with Bonita BPM through live exercises
> http://www.bonitasoft.com/be-part-of-it/events/bpm-camp-virtual- event?utm_
> source=Sourceforge_BPM_Camp_5_6_15&utm_medium=email&utm_campaign=VA_SF
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
|
