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Diffstat (limited to 'bip-0325.mediawiki')
| -rw-r--r-- | bip-0325.mediawiki | 83 |
1 files changed, 49 insertions, 34 deletions
diff --git a/bip-0325.mediawiki b/bip-0325.mediawiki index c0db46d..be4ad02 100644 --- a/bip-0325.mediawiki +++ b/bip-0325.mediawiki @@ -3,9 +3,10 @@ Layer: Applications Title: Signet Author: Karl-Johan Alm <karljohan-alm@garage.co.jp> + Anthony Towns <aj@erisian.com.au> Comments-Summary: No comments yet. Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0325 - Status: Draft + Status: Proposed Type: Standards Track Created: 2019-03-20 License: CC0-1.0 @@ -21,41 +22,58 @@ Testnet is a great place to try out new things without risking real money, but i A new type of test network would be more suitable for integration testing by organizations such as exchanges, or testing of next generation Layer-2 protocols like Eltoo or sidechain pegs. The goal is not to be perfectly reliable but rather to have a predictable amount of unreliability. You want a test network to behave like mainnet (i.e. no thousands of block reorgs) while also making it easier to trigger expected but rare events like a 6-block reorg. Regtest is not suitable for longer-term scenarios involving multiple independent parties because creating blocks costs nothing, so any party can completely control the test network. - == Specification == A new type of network ("signet"), which takes an additional consensus parameter called the challenge (scriptPubKey). The challenge can be a simple pubkey (P2PKH style), or a k-of-n multisig, or any other script you would want. -The witness commitment of the coinbase transaction is extended to include a secondary commitment (the signature/solution): +Signet requires all blocks to have a BIP 141 commitment in the coinbase transaction. In order to provide a non-empty solution to the block challenge the block's BIP 141 commitment's optional data must include an additional commitment of the signature/solution for the block: - 1-4 bytes - Push the following (x + 4) bytes + 1-5 bytes - Push the following (4 + x + y) bytes 4 bytes - Signet header (0xecc7daa2) - x bytes - Solution (sigScript) + x bytes - scriptSig + y bytes - scriptWitness + +In the special case where an empty solution is valid (ie scriptSig and scriptWitness are both empty) this additional commitment can optionally be left out. This special case is to allow non-signet-aware block generation code to be used to test a custom signet chain where the challenge is trivially true. + +The scriptSig is serialized by first encoding its length as CompactSize. The scriptWitness stack is serialized as described in BIP 141. + +Any push operations that do not start with the 4 byte Signet header are ignored. Multiple push operations with the 4 byte Signet header are ignored except for the first instance of the header. + +To sign the block or verify a block signature, two virtual transactions, each with a single input and output are constructed from the block as follows. + +The "to_spend" transaction is: -Any push operations that do not start with the 4 byte signet header are ignored. Multiple push operations with the 4 byte signet header are ignored except for the first entry. + nVersion = 0 + nLockTime = 0 + vin[0].prevout.hash = 0000...000 + vin[0].prevout.n = 0xFFFFFFFF + vin[0].nSequence = 0 + vin[0].scriptSig = OP_0 PUSH72[ block_data ] + vin[0].scriptWitness = [] + vout[0].nValue = 0 + vout[0].scriptPubKey = signet_challenge -Any signature operations contained within the challenge use SHA256d(modifiedBlockHash), i.e. the double-SHA256 digest of the following data as the sighash: +where block_data is the serialization of the block's nVersion, hashPrevBlock, signet_merkle_root, and nTime. The <code>signet_merkle_root</code> is obtained by generating the merkle root of the block transactions, after modifying the coinbase witness commitment by replacing the signet solution with an empty solution (that is, the witness commitment includes a four byte push of the Signet header with no additional solution data, and no prior pushes beginning with the Signet header). This means the merkle root of the block is different from the merkle root in the signet commitment. This is needed, because the signature can never be included in the very message (in this case, a block) that is being signed. -{|class="wikitable" style="text-align: center;" -|- -!Type -!Size -!Name -|- -|Int32||4||nVersion -|- -|Uint256||32||hashPrevBlock -|- -|Uint256||32||modifiedMerkleRoot -|- -|Uint32||4||nTime -|- -|Uint32||4||nBits -|} +The "to_sign" transaction is: -The <code>modifiedMerkleRoot</code> hash is obtained by generating the merkle root of the block transactions, with the coinbase witness commitment as is, without the signet extension. This means the merkle root of the block is different from the merkle root in the signet commitment. This is needed, because the signature can never be included in the very message (in this case, a block) that is being signed. Apart from the signature, to facilitate block generation (mining), the block nonce value is the only other component of the block that the signet signature does not commit to. When grinding proof of work, the extended nonce cannot be used as it would invalidate the signature. Instead, simply resigning the same (or an updated) block will give a new search space. + nVersion = 0 + nLockTime = 0 + vin[0].prevout.hash = to_spend.txid + vin[0].prevout.n = 0 + vin[0].nSequence = 0 + vin[0].sigScript = [ signet_solution sigScript (x bytes), if any ] + vin[0].scriptWitness = [ signet_solution scriptWitness (y bytes), if any ] + vout[0].nValue = 0 + vout[0].scriptPubKey = OP_RETURN -A block is considered fully validated if the above commitment is found, and its solution is valid. It is recommended that this verification is done directly before or after the witness commitment verification, as the data required to do both is approximately the same. +The scriptSig and/or scriptWitness for <code>vin[0]</code> are filled in from the Signet header push above. + +To simplify block generation (mining), the signature also does not commit to the block nonce value, so that rolling the nonce to generate proof-of-work does not also require regenerating signatures. When grinding proof of work, the extended nonce cannot be used as it would invalidate the signature. Instead, simply resigning the same (or an updated) block will give a new search space. + +A block is considered fully validated only if the to_sign transaction is a valid spend of the to_spend transaction. It is recommended that this verification is done directly before or after the witness commitment verification, as the data required to do both is approximately the same. + +There is one other acceptable special case: if a block's challenge is e.g. `OP_TRUE` (`0x51`), where an empty solution would result in success, the block is also considered valid if the signet commitment is absent. == Genesis Block and Message Start == @@ -63,11 +81,12 @@ The genesis block is the same for all signet networks, whereas the message start === Genesis Block === -* Time stamp: 1534313275 -* Nonce: 100123 -* Difficulty: 1e2adc28 +* Time stamp: 1598918400 +* Nonce: 52613770 +* Difficulty: 0x1e0377ae +* Version: 1 -The resulting genesis block hash is 0000032d7f67af9ec7b7152aea0fe7c95b9804ff973265e252f245e0ae61799d, and the block hex is 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. +The resulting genesis block hash is 00000008819873e925422c1ff0f99f7cc9bbb232af63a077a480a3633bee1ef6, and the block hex is 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. === Message Start === @@ -89,11 +108,7 @@ Other software need not add block signature validation code that they will not u == Reference implementation == -Pull request at https://github.com/bitcoin/bitcoin/pull/16411 - -== Acknowledgements == - -TODO +Pull request at https://github.com/bitcoin/bitcoin/pull/18267 == References == |