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@ -92,64 +92,6 @@ To achieve this, Bitcoin Core sets the +nLocktime+ on all new
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transactions to <current block # + 1> and sets the +nSequence+ on all
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the inputs to 0xFFFFFFFE to enable +nLocktime+.((("",
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startref="Stimelock07")))
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===== Segregated Witness addresses
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Even after segwit activation, it will take some time until most wallets
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are upgraded. At first, segwit will be embedded in P2SH, as we saw in
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the previous section, to ease compatibility between segit-aware and
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unaware wallets.
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However, once wallets are broadly supporting segwit, it makes sense to
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encode witness scripts directly in a native address format designed for
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segwit, rather than embed it in P2SH.
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The native segwit address format is defined in BIP-173:
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https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki[BIP-173]::
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Base32 address format for native v0-16 witness outputs
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BIP-173 only encodes witness (P2WPKH and P2WSH) scripts. It is not
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compatible with non-segwit P2PKH or P2SH scripts. BIP-173 is a
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checksummed Base32 encoding, as compared to the Base58 encoding of a
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"traditional" Bitcoin address. BIP-173 addesses are also called _bech32_
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addresses, pronounced "beh-ch thirty two", alluding to the use of a
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"BCH" error detection algorithm and 32-character encoding set.
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BIP-173 addresses use 32 lower-case-only alphanumeric character set,
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carefully selected to reduce errors from misreading or mistyping. By
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choosing a lower-case-only character set, bech32 is easier to read,
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speak, and 45% more efficient to encode in QR codes.
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The BCH error detection algorithm is a vast improvement over the
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previous checksum algorithm (from Base58Check), allowing not only
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detection but also _correction_ of errors. Address-input interfaces
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(such as text-fields in forms) can detect and highlight which character
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was most likely mistyped when they detect an error.
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From the BIP-173 specification, here are some examples of bech32 addresses:
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Mainnet P2WPKH:: bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4
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Testnet P2WPKH:: tb1qw508d6qejxtdg4y5r3zarvary0c5xw7kxpjzsx
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Mainnet P2WSH:: bc1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3qccfmv3
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Testnet P2WSH:: tb1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3q0sl5k7
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As you can see in these examples, a segwit bech32 string is up to 90
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characters long and consists of three parts:
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The human readable part:: This prefix "bc" or "tb" identifying mainnet
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or testnet.
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The separator:: The digit "1", which is not part of the 32-character
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encoding set and can only appear in this position as a separator
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The data part:: A minimum of 6 alphanumeric characters, the checksum
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encoded witness script
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At this time, only a few wallets accept or produce native segwit bech32
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addresses, but as segwit adoption increases, you will see these more and
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more often.
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==== Segregated Witness' New Signing Algorithm
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Segregated Witness modifies the semantics of the four signature
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David A. Harding
1 year ago