wire+chaincfg: add signet params

This commit adds all necessary chain parameters for connecting to the
public signet network.
Reference: bitcoin/bitcoin#18267

Author: guggero

chaincfg/genesis.go

@@ -170,3 +170,31 @@ var simNetGenesisBlock = wire.MsgBlock{
 	},
 	Transactions: []*wire.MsgTx{&genesisCoinbaseTx},
 }
+
+// sigNetGenesisHash is the hash of the first block in the block chain for the
+// signet test network.
+var sigNetGenesisHash = chainhash.Hash([chainhash.HashSize]byte{ // Make go vet happy.
+	0xf6, 0x1e, 0xee, 0x3b, 0x63, 0xa3, 0x80, 0xa4,
+	0x77, 0xa0, 0x63, 0xaf, 0x32, 0xb2, 0xbb, 0xc9,
+	0x7c, 0x9f, 0xf9, 0xf0, 0x1f, 0x2c, 0x42, 0x25,
+	0xe9, 0x73, 0x98, 0x81, 0x08, 0x00, 0x00, 0x00,
+})
+
+// sigNetGenesisMerkleRoot is the hash of the first transaction in the genesis
+// block for the signet test network. It is the same as the merkle root for
+// the main network.
+var sigNetGenesisMerkleRoot = genesisMerkleRoot
+
+// sigNetGenesisBlock defines the genesis block of the block chain which serves
+// as the public transaction ledger for the signet test network.
+var sigNetGenesisBlock = wire.MsgBlock{
+	Header: wire.BlockHeader{
+		Version:    1,
+		PrevBlock:  chainhash.Hash{},         // 0000000000000000000000000000000000000000000000000000000000000000
+		MerkleRoot: sigNetGenesisMerkleRoot,  // 4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b
+		Timestamp:  time.Unix(1598918400, 0), // 2020-09-01 00:00:00 +0000 UTC
+		Bits:       0x1e0377ae,               // 503543726 [000000377ae00000000000000000000000000000000000000000000000000000]
+		Nonce:      52613770,
+	},
+	Transactions: []*wire.MsgTx{&genesisCoinbaseTx},
+}

chaincfg/params.go

@@ -38,6 +38,10 @@ var (
 	// simNetPowLimit is the highest proof of work value a Bitcoin block
 	// can have for the simulation test network.  It is the value 2^255 - 1.
 	simNetPowLimit = new(big.Int).Sub(new(big.Int).Lsh(bigOne, 255), bigOne)
+
+	// sigNetPowLimit is the highest proof of work value a bitcoin block can
+	// have for the signet test network. It is the value 0x0377ae << 212.
+	sigNetPowLimit = new(big.Int).Lsh(new(big.Int).SetInt64(0x0377ae), 212)
 )
 
 // Checkpoint identifies a known good point in the block chain.  Using
@@ -96,6 +100,11 @@ const (
 	// includes the deployment of BIPS 141, 142, 144, 145, 147 and 173.
 	DeploymentSegwit
 
+	// DeploymentTaproot defines the rule change deployment ID for the
+	// Taproot (+Schnorr) soft-fork package. The taproot package includes
+	// the deployment of BIPS 340, 341 and 342.
+	DeploymentTaproot
+
 	// NOTE: DefinedDeployments must always come last since it is used to
 	// determine how many defined deployments there currently are.
 
@@ -578,6 +587,91 @@ var SimNetParams = Params{
 	HDCoinType: 115, // ASCII for s
 }
 
+// SigNetParams defines the network parameters for the signet Bitcoin network.
+// Not to be confused with the regression test network, this network is
+// sometimes simply called "signet".
+var SigNetParams = Params{
+	Name:        "signet",
+	Net:         wire.SigNet,
+	DefaultPort: "38333",
+	DNSSeeds: []DNSSeed{
+		{"178.128.221.177", false},
+		{"2a01:7c8:d005:390::5", false},
+		{"v7ajjeirttkbnt32wpy3c6w3emwnfr3fkla7hpxcfokr3ysd3kqtzmqd.onion:38333", false},
+	},
+
+	// Chain parameters
+	GenesisBlock:             &sigNetGenesisBlock,
+	GenesisHash:              &sigNetGenesisHash,
+	PowLimit:                 sigNetPowLimit,
+	PowLimitBits:             0x1e0377ae,
+	BIP0034Height:            1,
+	BIP0065Height:            1,
+	BIP0066Height:            1,
+	CoinbaseMaturity:         100,
+	SubsidyReductionInterval: 210000,
+	TargetTimespan:           time.Hour * 24 * 14, // 14 days
+	TargetTimePerBlock:       time.Minute * 10,    // 10 minutes
+	RetargetAdjustmentFactor: 4,                   // 25% less, 400% more
+	ReduceMinDifficulty:      true,
+	MinDiffReductionTime:     time.Minute * 20, // TargetTimePerBlock * 2
+	GenerateSupported:        false,
+
+	// Checkpoints ordered from oldest to newest.
+	Checkpoints: nil,
+
+	// Consensus rule change deployments.
+	//
+	// The miner confirmation window is defined as:
+	//   target proof of work timespan / target proof of work spacing
+	RuleChangeActivationThreshold: 1512, // 95% of 2016
+	MinerConfirmationWindow:       2016,
+	Deployments: [DefinedDeployments]ConsensusDeployment{
+		DeploymentTestDummy: {
+			BitNumber:  28,
+			StartTime:  1199145601, // January 1, 2008 UTC
+			ExpireTime: 1230767999, // December 31, 2008 UTC
+		},
+		DeploymentCSV: {
+			BitNumber:  0,
+			StartTime:  0,             // Always available for vote
+			ExpireTime: math.MaxInt64, // Never expires
+		},
+		DeploymentSegwit: {
+			BitNumber:  1,
+			StartTime:  0,             // Always available for vote
+			ExpireTime: math.MaxInt64, // Never expires.
+		},
+		DeploymentTaproot: {
+			BitNumber:  2,
+			StartTime:  0,             // Always available for vote
+			ExpireTime: math.MaxInt64, // Never expires.
+		},
+	},
+
+	// Mempool parameters
+	RelayNonStdTxs: true,
+
+	// Human-readable part for Bech32 encoded segwit addresses, as defined in
+	// BIP 173.
+	Bech32HRPSegwit: "tb", // always tb for test net
+
+	// Address encoding magics
+	PubKeyHashAddrID:        0x6f, // starts with m or n
+	ScriptHashAddrID:        0xc4, // starts with 2
+	WitnessPubKeyHashAddrID: 0x03, // starts with QW
+	WitnessScriptHashAddrID: 0x28, // starts with T7n
+	PrivateKeyID:            0xef, // starts with 9 (uncompressed) or c (compressed)
+
+	// BIP32 hierarchical deterministic extended key magics
+	HDPrivateKeyID: [4]byte{0x04, 0x35, 0x83, 0x94}, // starts with tprv
+	HDPublicKeyID:  [4]byte{0x04, 0x35, 0x87, 0xcf}, // starts with tpub
+
+	// BIP44 coin type used in the hierarchical deterministic path for
+	// address generation.
+	HDCoinType: 1,
+}
+
 var (
 	// ErrDuplicateNet describes an error where the parameters for a Bitcoin
 	// network could not be set due to the network already being a standard

chaincfg/params_test.go

@@ -6,6 +6,8 @@ package chaincfg
 
 import (
 	"bytes"
+	"encoding/hex"
+	"math/big"
 	"testing"
 )
 
@@ -84,3 +86,14 @@ func TestInvalidHDKeyID(t *testing.T) {
 		t.Fatalf("HDPrivateKeyToPublicKeyID: want err ErrUnknownHDKeyID, got %v", err)
 	}
 }
+
+func TestSigNetPowLimit(t *testing.T) {
+	sigNetPowLimitHex, _ := hex.DecodeString(
+		"000000377ae00000000000000000000000000000000000000000000000000000",
+	)
+	powLimit := new(big.Int).SetBytes(sigNetPowLimitHex)
+	if sigNetPowLimit.Cmp(powLimit) != 0 {
+		t.Fatalf("Signet PoW limit bits (%s) not equal to big int (%s)",
+			sigNetPowLimit.Text(16), powLimit.Text(16))
+	}
+}

wire/protocol.go

@@ -157,6 +157,9 @@ const (
 
 	// SimNet represents the simulation test network.
 	SimNet BitcoinNet = 0x12141c16
+
+	// SigNet represents the signet test network.
+	SigNet BitcoinNet = 0xe7ca5a64
 )
 
 // bnStrings is a map of bitcoin networks back to their constant names for
@@ -166,6 +169,7 @@ var bnStrings = map[BitcoinNet]string{
 	TestNet:  "TestNet",
 	TestNet3: "TestNet3",
 	SimNet:   "SimNet",
+	SigNet:   "SigNet",
 }
 
 // String returns the BitcoinNet in human-readable form.