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Date: Mon, 17 Mar 2025 09:14:05 -0700 (PDT)
From: weichu deng <weichudeng@stu2024.jnu.edu.cn>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
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Subject: =?UTF-8?Q?=5Bbitcoindev=5D_New_Proposal=EF=BC=9AString_Substring_Search_?=
=?UTF-8?Q?in_Bitcoin_Script_=2D_OP=5FISSUBSTR?=
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boundary="----=_Part_276941_2063444441.1742228045178"
------=_Part_276941_2063444441.1742228045178
Content-Type: text/plain; charset="UTF-8"
Dear fellow Bitcoin developers,
I am pleased to present a new BIP proposal. This proposal introduces a new
opcode for Bitcoin scripts: OP_ISSUBSTR.
*Abstract*
This BIP introduces two string opcodes, OP_ISSUBSTR and OP_ISSUBSTRVERIFY
(similar to the relationship between OP_EQUAL and OP_EQUALVERIFY), to
determine whether one string is a substring of another. As these opcodes do
not alter any blockchain state, they are secure.
*Specification*
These opcodes check if the second string on the stack is a substring of the
first string. If the opcode is OP_ISSUBSTRVERIFY, it verifies the condition
and throws an error if false, without retaining the result.
*Execution Process*
1. Take the two strings at the top of the stack.
2. Use standard library functions to compare the two strings.
3. Pop the two strings from the stack and push the result onto the stack.
4. If the opcode is OP_ISSUBSTRVERIFY, do not push the result.
*Motivation*
The absence of string operations in Bitcoin scripts restricts its
applicability. When developers need string operations for applications,
they must simulate these functions through off-chain preprocessing or
complex scripts, increasing development difficulty and potentially
introducing centralized dependencies.
Early Bitcoin versions supported some string operations, such as OP_SUBSTR,
which extracted a substring of specified position and length from a string,
replacing the original string. For security reasons, OP_SUBSTR was disabled
in Bitcoin v0.3.10 and later versions due to a vulnerability
(CVE-2010-5137) caused by OP_LSHIFT. To prevent similar overflow
vulnerabilities, Bitcoin disabled several opcodes, including OP_SUBSTR. As
Bitcoin adoption grows, the limitations of lacking string operations have
become more evident. Our proposed OP_ISSUBSTR adds string search
functionality to Bitcoin scripts without changing any state, making it safe.
*Advantages *
1. *Enhanced Script Functionality and Flexibility* Developers can
process string logic on-chain without off-chain reliance. For example, in
multi-signature wallets, developers can verify specific signer information
or remarks directly in scripts using OP_ISSUBSTR to check transaction
comments or signature fields for particular substrings.
2. *Support for String Searching* In some scenarios, developers need to
verify if parts of a string match a format or contain specific data. For
example, checking if a payment transaction's payee name matches a preset
value.
3. *Conversion of Non-deterministic Algorithms to Deterministic Ones*
Some signature algorithms or hash functions produce non-deterministic
outputs. OP_ISSUBSTR allows developers to check if these outputs contain
known substrings in scripts, converting non-deterministic results to
deterministic ones. For example, verifying if a hash value contains a
specific hexadecimal sequence (like "0000") to trigger contract logic.
4. *Simplified Address Verification Logic* Bitcoin addresses typically
start with specific prefixes or suffixes. OP_ISSUBSTR enables direct
address format verification in scripts. For example, checking if a
transaction target address starts with "bc1" to ensure validity or detect
"address pollution" attacks.
5. *Integration with Modern Programming Languages* Modern languages
widely support string operations. OP_ISSUBSTR makes Bitcoin scripts more
aligned with these languages, lowering the barrier for developers.
We have provided detailed documentation and a reference implementation in
the BIP draft. You can read the full proposal here:
https://github.com/Weichu-Deng/bips/blob/OP_ISSUBSTR/bip-yongdong%20wu-OP_ISSUBSTR.md
Thank you for your feedback!
With respect,
Weichu Deng
weichudeng@stu2024.jnu.edu.cn
--
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------=_Part_276941_2063444441.1742228045178
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
<p><span lang=3D"EN-US">Dear fellow Bitcoin developers,</span></p>
<p><span lang=3D"EN-US">=C2=A0</span></p>
<p><span lang=3D"EN-US">I am pleased to present a new BIP proposal.
This proposal introduces a new opcode for Bitcoin scripts: OP_ISSUBSTR.</sp=
an></p><p><span lang=3D"EN-US"><br /></span></p>
<p><b><span lang=3D"EN-US">Abstract</span></b><span lang=3D"EN-US"></span><=
/p>
<p><span lang=3D"EN-US">This BIP introduces two string opcodes,
OP_ISSUBSTR and OP_ISSUBSTRVERIFY (similar to the relationship between OP_E=
QUAL
and OP_EQUALVERIFY), to determine whether one string is a substring of anot=
her.
As these opcodes do not alter any blockchain state, they are secure.</span>=
</p>
<p><span lang=3D"EN-US">=C2=A0</span></p>
<p><b><span lang=3D"EN-US">Specification</span></b><span lang=3D"EN-US"></s=
pan></p>
<p><span lang=3D"EN-US">These opcodes check if the second string on
the stack is a substring of the first string. If the opcode is
OP_ISSUBSTRVERIFY, it verifies the condition and throws an error if false,
without retaining the result.</span></p>
<p><span lang=3D"EN-US">=C2=A0</span></p>
<p><b><span lang=3D"EN-US">Execution Process</span></b><span lang=3D"EN-US"=
></span></p>
<ol style=3D"margin-top: 0cm;" start=3D"1" type=3D"1">
<li><span lang=3D"EN-US">Take the two strings at the top of the stack.</sp=
an></li>
<li><span lang=3D"EN-US">Use standard library functions to compare the two=
strings.</span></li>
<li><span lang=3D"EN-US">Pop the two strings from the stack and push the r=
esult onto the
stack.</span></li>
<li><span lang=3D"EN-US">If the opcode is OP_ISSUBSTRVERIFY, do not push t=
he result.</span></li>
</ol>
<p><b><span lang=3D"EN-US">Motivation</span></b><span lang=3D"EN-US"></span=
></p>
<p><span lang=3D"EN-US">The absence of string operations in Bitcoin
scripts restricts its applicability. When developers need string operations=
for
applications, they must simulate these functions through off-chain
preprocessing or complex scripts, increasing development difficulty and
potentially introducing centralized dependencies.</span></p>
<p><span lang=3D"EN-US">=C2=A0</span></p>
<p><span lang=3D"EN-US">Early Bitcoin versions supported some
string operations, such as OP_SUBSTR, which extracted a substring of specif=
ied
position and length from a string, replacing the original string. For secur=
ity
reasons, OP_SUBSTR was disabled in Bitcoin v0.3.10 and later versions due t=
o a
vulnerability (CVE-2010-5137) caused by OP_LSHIFT. To prevent similar overf=
low
vulnerabilities, Bitcoin disabled several opcodes, including OP_SUBSTR. As
Bitcoin adoption grows, the limitations of lacking string operations have b=
ecome
more evident. Our proposed OP_ISSUBSTR adds string search functionality to
Bitcoin scripts without changing any state, making it safe.</span></p>
<p><span lang=3D"EN-US">=C2=A0</span></p>
<p><b><span lang=3D"EN-US">Advantages </span></b><span lang=3D"EN-US"></spa=
n></p>
<ol style=3D"margin-top: 0cm;" start=3D"1" type=3D"1">
<li><b><span lang=3D"EN-US">Enhanced Script Functionality and Flexibility<=
/span></b><span lang=3D"EN-US"> Developers can process string logic on-chai=
n without off-chain
reliance. For example, in multi-signature wallets, developers can veri=
fy
specific signer information or remarks directly in scripts using
OP_ISSUBSTR to check transaction comments or signature fields for
particular substrings.</span></li>
<li><b><span lang=3D"EN-US">Support for String Searching</span></b><span l=
ang=3D"EN-US"> In
some scenarios, developers need to verify if parts of a string match a
format or contain specific data. For example, checking if a payment
transaction's payee name matches a preset value.</span></li>
<li><b><span lang=3D"EN-US">Conversion of Non-deterministic Algorithms to =
Deterministic
Ones</span></b><span lang=3D"EN-US"> Some signature algorithms or hash
functions produce non-deterministic outputs. OP_ISSUBSTR allows develo=
pers
to check if these outputs contain known substrings in scripts, convert=
ing
non-deterministic results to deterministic ones. For example, verifyin=
g if
a hash value contains a specific hexadecimal sequence (like
"0000") to trigger contract logic.</span></li>
<li><b><span lang=3D"EN-US">Simplified Address Verification Logic</span></=
b><span lang=3D"EN-US"> Bitcoin addresses typically start with specific pre=
fixes or
suffixes. OP_ISSUBSTR enables direct address format verification in
scripts. For example, checking if a transaction target address starts =
with
"bc1" to ensure validity or detect "address pollution"
attacks.</span></li>
<li><b><span lang=3D"EN-US">Integration with Modern Programming Languages<=
/span></b><span lang=3D"EN-US"> Modern languages widely support string oper=
ations. OP_ISSUBSTR
makes Bitcoin scripts more aligned with these languages, lowering the
barrier for developers.</span></li>
</ol>
<p style=3D"margin-left: 36pt;"><span lang=3D"EN-US">=C2=A0</span></p>
<p><span lang=3D"EN-US">We have provided detailed documentation and
a reference implementation in the BIP draft. You can read the full proposal
here: <a href=3D"https://github.com/Weichu-Deng/bips/blob/OP_ISSUBSTR/bip-y=
ongdong%20wu-OP_ISSUBSTR.md" target=3D"_blank">https://github.com/Weichu-De=
ng/bips/blob/OP_ISSUBSTR/bip-yongdong%20wu-OP_ISSUBSTR.md</a></span></p><p>=
<br /></p>
<p><span lang=3D"EN-US">Thank you for your feedback!=C2=A0</span></p><p><sp=
an lang=3D"EN-US">With respect,</span></p>
<p><span lang=3D"EN-US">Weichu
Deng</span></p><p>=C2=A0<a href=3D"mailto:weichudeng@stu2024.jnu.edu.cn" ta=
rget=3D"_blank">weichudeng@stu2024.jnu.edu.cn</a></p>
<p><span lang=3D"EN-US">=C2=A0</span></p>
<p></p>
-- <br />
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quot;Bitcoin Development Mailing List" group.<br />
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bitcoindev/f844a85e-8be8-4429-8687-bc19dd4b96ffn%40googlegroups.com?utm_med=
ium=3Demail&utm_source=3Dfooter">https://groups.google.com/d/msgid/bitcoind=
ev/f844a85e-8be8-4429-8687-bc19dd4b96ffn%40googlegroups.com</a>.<br />
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