Segregated Witness - Revision history

NotATether: Expand Nested SegWit section: P2SH wrap, redeem/witness spend, fee vs native bc1, compatibility note

2026-09-26T07:29:34Z

Expand Nested SegWit section: P2SH wrap, redeem/witness spend, fee vs native bc1, compatibility note

← Older revision		Revision as of 07:29, 26 September 2026
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	== Nested SegWit ==		== Nested SegWit ==

	~~'''~~Nested SegWit~~'''~~ is a ~~[[Segregated Witness]]~~ output wrapped in a [[P2SH]] script so that senders who only understand Base58 P2SH addresses can still pay a SegWit receiver. The ~~two common forms are P2SH-P2WPKH (~~a version-0 public-key-hash ~~witness program inside~~ P2SH) ~~and P2SH~~-~~P2WSH (a version~~-0 script-hash ~~witness program inside~~ P2SH). On mainnet the address is a Base58Check P2SH string beginning with <code>3</code>~~. Nested outputs are larger than native witness outputs and were a compatibility step after~~ the ~~SegWit soft fork~~.		Nested SegWit is a SegWit output wrapped in a [[P2SH]] script so that senders who only understand Base58 P2SH addresses can still pay a SegWit receiver. The redeem script is a version-0 witness program: either a twenty-byte public-key hash (often called P2SH-P2WPKH) or a thirty-two-byte script hash (P2SH-P2WSH). On mainnet the payment address is a Base58Check P2SH string beginning with <code>3</code>, the same prefix as ordinary P2SH.

			When the output is spent, the witness carries the signature and public key (or the witness script and its stack) while the scriptSig only pushes the redeem script that commits to that witness program. The wrapping adds bytes compared with a native witness output that uses a Bech32 address beginning with <code>bc1</code>, so nested receives usually pay a higher fee for the same spend. Wallets adopted nested outputs as a compatibility step after the SegWit soft fork so older software could send to SegWit users without understanding native witness addresses. New receives prefer native SegWit; nested remains valid and common where Base58-only senders still matter.
	==See Also==		==See Also==

NotATether: add Nested SegWit section (P2SH-wrapped witness)

2026-09-03T19:30:22Z

add Nested SegWit section (P2SH-wrapped witness)

← Older revision		Revision as of 19:30, 3 September 2026
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	On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 0148\|BIP 148]] where the [[economic majority]] would bypass the blocking miners and activate segregated witness on their own.		On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 0148\|BIP 148]] where the [[economic majority]] would bypass the blocking miners and activate segregated witness on their own.
	This required some coordination amongst the economic majority, but was ultimately successful, activating Segwit on Bitcoin soon after 1st August 2017.<ref>[https://web.archive.org/web/20210224032019/https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality// BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality (Archived February 2021)]</ref>		This required some coordination amongst the economic majority, but was ultimately successful, activating Segwit on Bitcoin soon after 1st August 2017.<ref>[https://web.archive.org/web/20210224032019/https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality// BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality (Archived February 2021)]</ref>

			== Nested SegWit ==

			'''Nested SegWit''' is a [[Segregated Witness]] output wrapped in a [[P2SH]] script so that senders who only understand Base58 P2SH addresses can still pay a SegWit receiver. The two common forms are P2SH-P2WPKH (a version-0 public-key-hash witness program inside P2SH) and P2SH-P2WSH (a version-0 script-hash witness program inside P2SH). On mainnet the address is a Base58Check P2SH string beginning with <code>3</code>. Nested outputs are larger than native witness outputs and were a compatibility step after the SegWit soft fork.

	==See Also==		==See Also==

Calliptamus: /* History and Activation */

2025-05-17T08:02:27Z

History and Activation

← Older revision		Revision as of 08:02, 17 May 2025
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	During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism.		During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism.
	On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypass the blocking miners and activate segregated witness on their own.		On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 0148\|BIP 148]] where the [[economic majority]] would bypass the blocking miners and activate segregated witness on their own.
	This required some coordination amongst the economic majority, but was ultimately successful, activating Segwit on Bitcoin soon after 1st August 2017.<ref>[https://web.archive.org/web/20210224032019/https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality// BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality (Archived February 2021)]</ref>		This required some coordination amongst the economic majority, but was ultimately successful, activating Segwit on Bitcoin soon after 1st August 2017.<ref>[https://web.archive.org/web/20210224032019/https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality// BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality (Archived February 2021)]</ref>

Diegorodriguezv: /* History and Activation */ Changed the link to archived version because the original was deleted

2021-03-14T06:16:22Z

History and Activation: Changed the link to archived version because the original was deleted

← Older revision		Revision as of 06:16, 14 March 2021
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	During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism.		During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism.
	On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypass the blocking miners and activate segregated witness on their own.		On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypass the blocking miners and activate segregated witness on their own.
	This required some coordination amongst the economic majority, but was ultimately successful, activating Segwit on Bitcoin soon after 1st August 2017.<ref>[https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality/ BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality]</ref>		This required some coordination amongst the economic majority, but was ultimately successful, activating Segwit on Bitcoin soon after 1st August 2017.<ref>[https://web.archive.org/web/20210224032019/https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality// BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality (Archived February 2021)]</ref>

	==See Also==		==See Also==

Deyw: include link to Wikipedia

2019-09-27T11:25:06Z

include link to Wikipedia

← Older revision		Revision as of 11:25, 27 September 2019
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	* [https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segregated Witness Benefits]		* [https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segregated Witness Benefits]
	* [https://bitcoincore.org/en/segwit_wallet_dev/ Segregated Witness Wallet Developer Guide]		* [https://bitcoincore.org/en/segwit_wallet_dev/ Segregated Witness Wallet Developer Guide]
			* [[Wikipedia:SegWit\|Wikipedia: SegWit]]
	{{stub}}		{{stub}}

Jhfrontz: link to wu

2019-01-22T20:59:45Z

link to wu

← Older revision		Revision as of 20:59, 22 January 2019
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	\|activated=Block #481824<br/>2017-08-24 01:57:37		\|activated=Block #481824<br/>2017-08-24 01:57:37
	}}'''Segregated Witness''' (abbreviated as '''SegWit''') is an implemented protocol upgrade intended to provide protection from [[transaction malleability]] and [[Block size limit controversy\|increase block capacity]]. SegWit separates the ''witness'' from the list of inputs. The witness contains data required to check transaction validity but is not required to determine transaction effects.		}}'''Segregated Witness''' (abbreviated as '''SegWit''') is an implemented protocol upgrade intended to provide protection from [[transaction malleability]] and [[Block size limit controversy\|increase block capacity]]. SegWit separates the ''witness'' from the list of inputs. The witness contains data required to check transaction validity but is not required to determine transaction effects.
	Additionally, a new ''weight'' parameter is defined, and blocks are allowed to have at most 4 million weight units (WU). Non-witness and pre-segwit witness bytes weigh 4 WU, but each byte of Segwit witness data only weighs 1 WU, allowing blocks that are larger than 1 MB without a hardforking change.		Additionally, a new ''weight'' parameter is defined, and blocks are allowed to have at most 4 million [[weight units]] (WU). Non-witness and pre-segwit witness bytes weigh 4 WU, but each byte of Segwit witness data only weighs 1 WU, allowing blocks that are larger than 1 MB without a hardforking change.

	After the successful activations of OP_CLTV and OP_CSV, SegWit was the last protocol change needed to make the [[Lightning Network]] safe to deploy on the Bitcoin network.		After the successful activations of OP_CLTV and OP_CSV, SegWit was the last protocol change needed to make the [[Lightning Network]] safe to deploy on the Bitcoin network.

Luke-jr: Remove misinformation, add clarifications

2019-01-17T20:48:27Z

Remove misinformation, add clarifications

← Older revision		Revision as of 20:48, 17 January 2019
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	\|lockin=Block #479708<br/>2017-08-08 19:05:58		\|lockin=Block #479708<br/>2017-08-08 19:05:58
	\|activated=Block #481824<br/>2017-08-24 01:57:37		\|activated=Block #481824<br/>2017-08-24 01:57:37
	}}'''Segregated Witness''' (abbreviated as '''SegWit''') is an implemented protocol upgrade intended to provide protection from [[transaction malleability]] and [[Block size limit controversy\|increase block capacity]]. SegWit ~~defines a new structure called a~~ ''witness'' ~~that is committed to blocks separately~~ from the ~~transaction merkle tree~~. ~~This structure~~ contains data required to check transaction validity but is not required to determine transaction effects. ~~In particular, signatures and redeem scripts are moved into this new structure, which does not count towards the traditional [[Block size limit controversy\|1 MB block size limit]]. Instead~~, a new ''weight'' parameter is defined, and blocks are allowed to have at most 4 million weight units (WU). ~~A byte in the original 1 MB zone of the block weighs~~ 4 WU, but a byte ~~in a~~ witness ~~structure~~ only weighs 1 WU, allowing blocks that are ~~technically~~ larger than 1 MB without a hardforking change.		}}'''Segregated Witness''' (abbreviated as '''SegWit''') is an implemented protocol upgrade intended to provide protection from [[transaction malleability]] and [[Block size limit controversy\|increase block capacity]]. SegWit separates the ''witness'' from the list of inputs. The witness contains data required to check transaction validity but is not required to determine transaction effects.
			Additionally, a new ''weight'' parameter is defined, and blocks are allowed to have at most 4 million weight units (WU). Non-witness and pre-segwit witness bytes weigh 4 WU, but each byte of Segwit witness data only weighs 1 WU, allowing blocks that are larger than 1 MB without a hardforking change.

	After the successful activations of OP_CLTV and OP_CSV, SegWit was the last protocol change needed to make the [[Lightning Network]] safe to deploy on the Bitcoin network.		After the successful activations of OP_CLTV and OP_CSV, SegWit was the last protocol change needed to make the [[Lightning Network]] safe to deploy on the Bitcoin network.

	Because the witness ~~structure~~ contains [[Script]] versioning, it is also possible to make changes to or introduce new opcodes to SegWit scripts that would have originally required ~~a hardfork~~ to function without SegWit.		Because the new witness field contains [[Script]] versioning, it is also possible to make changes to or introduce new opcodes to SegWit scripts that would have originally required additional complexity to function without SegWit.

	~~=== Question: "How do I get cheaper transactions?"===~~

	One of the features made available by segwit is a larger [[maximum block size]]. Since a block can hold more data, transactions that can use that new space may be cheaper than they would if the older and smaller maximum block size was still enforced. To get cheaper transactions, you have to:

	~~# Install a SegWit-supporting wallet.~~
	# Receive money on new SegWit addresses, which start with 3. You must generate new addresses; your old addresses will never be SegWit addresses. Note that not all addresses starting with 3 are SegWit addresses, and it is impossible to tell just from looking at an address whether it is a SegWit address.
	# Whenever you ''spend BTC which you have received via SegWit addresses'', you will receive the SegWit discount. If you send a transaction spending some BTC received via non-SegWit addresses and some BTC received via SegWit addresses, you will receive a partial discount. The destination address doesn't matter.

	~~There are no compatibility issues: non-SegWit wallets can send BTC to SegWit addresses, and SegWit wallets can send BTC to non-SegWit addresses~~.

	=== History and Activation ===		=== History and Activation ===

	During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism. On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would ~~bypassing~~ the blocking miners and activate segregated witness on ~~its~~ own. This required some coordination amongst the economic majority, but was ultimately successful ~~as the miners caving in and activated segregated witness ahead of time which was added to bitcoin~~ soon after 1st August 2017~~, the BIP 148 flag day~~.<ref>[https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality/ BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality]</ref>		During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism.
			On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypass the blocking miners and activate segregated witness on their own.
			This required some coordination amongst the economic majority, but was ultimately successful, activating Segwit on Bitcoin soon after 1st August 2017.<ref>[https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality/ BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality]</ref>

	==See Also==		==See Also==

Belcher: /* History and Activation */ added link to bitcoinmagazine's article on segwit's history

2018-08-06T14:50:45Z

History and Activation: added link to bitcoinmagazine's article on segwit's history

← Older revision		Revision as of 14:50, 6 August 2018
Line 27:		Line 27:
	=== History and Activation ===		=== History and Activation ===

	During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism. On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypassing the blocking miners and activate segregated witness on its own. This required some coordination amongst the economic majority, but was ultimately successful as the miners caving in and activated segregated witness ahead of time which was added to bitcoin soon after 1st August 2017, the BIP 148 flag day.		During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism. On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypassing the blocking miners and activate segregated witness on its own. This required some coordination amongst the economic majority, but was ultimately successful as the miners caving in and activated segregated witness ahead of time which was added to bitcoin soon after 1st August 2017, the BIP 148 flag day.<ref>[https://bitcoinmagazine.com/articles/long-road-segwit-how-bitcoins-biggest-protocol-upgrade-became-reality/ BitcoinMagazine: The Long Road to SegWit: How Bitcoin’s Biggest Protocol Upgrade Became Reality]</ref>

	==See Also==		==See Also==

Belcher: /* History and Activation */ made slightly more accurate by mentioning that UASF caused the miners to cave

2018-05-26T19:59:34Z

History and Activation: made slightly more accurate by mentioning that UASF caused the miners to cave

← Older revision		Revision as of 19:59, 26 May 2018
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	=== History and Activation ===		=== History and Activation ===

	During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism. ~~Ultimately~~ the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]]~~. The~~ deadlock was ~~solved~~ by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypassing the blocking miners and activate segregated witness on its own. This required some coordination amongst the economic majority, but was successful and so segregated witness was added to bitcoin soon after 1st August 2017, the BIP 148 flag day.		During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism. On a technical level, the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]], so the deadlock was possible to solve by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypassing the blocking miners and activate segregated witness on its own. This required some coordination amongst the economic majority, but was ultimately successful as the miners caving in and activated segregated witness ahead of time which was added to bitcoin soon after 1st August 2017, the BIP 148 flag day.

	==See Also==		==See Also==

Belcher: Add short and quick summary of the bip148 uasf which lead to the activation of segwit

2018-05-25T16:50:15Z

Add short and quick summary of the bip148 uasf which lead to the activation of segwit

← Older revision		Revision as of 16:50, 25 May 2018
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	{{infobox ~~miner activated fork~~\|title=SegWit\|image=<hr style="background-color: #f9f9f9;"/>[[File:Segwit.png\|256px]]<hr style="background-color: #f9f9f9;"/>		{{infobox \|title=SegWit\|image=<hr style="background-color: #f9f9f9;"/>[[File:Segwit.png\|256px]]<hr style="background-color: #f9f9f9;"/>
	\|fulltitle=Segregated Witness (Consensus layer)		\|fulltitle=Segregated Witness (Consensus layer)
	\|bipnumber=[[BIP_0141\|BIP 141]]		\|bipnumber=[[BIP_0141\|BIP 141]]
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	There are no compatibility issues: non-SegWit wallets can send BTC to SegWit addresses, and SegWit wallets can send BTC to non-SegWit addresses.		There are no compatibility issues: non-SegWit wallets can send BTC to SegWit addresses, and SegWit wallets can send BTC to non-SegWit addresses.

			=== History and Activation ===

			During 2016 and 2017 activation of segregated witness was blocked by miners for political reasons by exploiting a flaw in the [[BIP 9]] activation mechanism. Ultimately the consensus rules of bitcoin are controlled by the [[economic majority]] not the [[Bitcoin is not ruled by miners\|miners]]. The deadlock was solved by creating a [[user activated soft fork]] [[BIP 148]] where the [[economic majority]] would bypassing the blocking miners and activate segregated witness on its own. This required some coordination amongst the economic majority, but was successful and so segregated witness was added to bitcoin soon after 1st August 2017, the BIP 148 flag day.

	==See Also==		==See Also==