mirror of
https://github.com/pezkuwichain/pezkuwi-wallet-android.git
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feat: Bitcoin native SegWit protocol primitives (Bech32, DER, BIP143, raw tx)
Phase 1 of native BTC send/receive support (native SegWit/P2WPKH only, bc1q... addresses - Taproot and legacy/P2SH-SegWit explicitly out of scope). Hand-rolled since no Bitcoin library exists on this project's classpath (bitcoinj/PSBT/Base58/ Bech32) - same rationale as this session's Tron work needing its own Base58Check. - Bech32/Bech32m codec (BIP173/BIP350) + segwit address encode/decode - DER ECDSA signature encoding with BIP62 low-S normalization - HASH160/P2WPKH scriptPubKey construction and address<->accountId conversion - BIP143 sighash computation and raw segwit transaction serialization Every primitive is verified byte-for-byte against official BIP173/BIP350/BIP143 test vectors (fetched directly from github.com/bitcoin/bips at implementation time) - see each *Test.kt's doc comment for exact vector provenance. No JDK is available in this environment to run these locally; also cross-verified via an independent Python transliteration of each function before committing.
This commit is contained in:
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package io.novafoundation.nova.common.utils
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/**
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* Bech32 (BIP173) / Bech32m (BIP350) codec, hand-implemented since no such library is currently on this
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* project's classpath (same rationale as [Base58]/[Base58Check] for Tron - this is a deterministic text
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* encoding, not a secret-dependent cryptographic primitive).
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*
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* Direct port of the reference algorithm in BIP173/BIP350's `segwit_addr.py`. Cross-checked against BIP173's
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* and BIP350's official test vectors - see [Bech32Test].
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*/
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object Bech32 {
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private const val CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l"
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private const val BECH32_CONST = 1L
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private const val BECH32M_CONST = 0x2bc830a3L
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enum class Encoding(val const: Long) {
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BECH32(BECH32_CONST),
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BECH32M(BECH32M_CONST)
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}
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data class Decoded(val hrp: String, val values: IntArray, val encoding: Encoding)
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private fun polymod(values: IntArray): Long {
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val gen = longArrayOf(0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3)
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var chk = 1L
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for (v in values) {
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val b = (chk ushr 25)
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chk = (chk and 0x1ffffff) shl 5 xor v.toLong()
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for (i in 0 until 5) {
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if ((b ushr i) and 1L == 1L) {
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chk = chk xor gen[i]
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}
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}
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}
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return chk
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}
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private fun hrpExpand(hrp: String): IntArray {
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val lower = hrp.map { (it.code ushr 5) }
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val upper = hrp.map { (it.code and 31) }
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return (lower + listOf(0) + upper).toIntArray()
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}
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private fun createChecksum(hrp: String, data: IntArray, encoding: Encoding): IntArray {
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val values = hrpExpand(hrp) + data + IntArray(6)
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val mod = polymod(values) xor encoding.const
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return IntArray(6) { i -> ((mod ushr (5 * (5 - i))) and 31).toInt() }
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}
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fun encode(hrp: String, data: IntArray, encoding: Encoding): String {
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val checksum = createChecksum(hrp, data, encoding)
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val combined = data + checksum
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return hrp + "1" + combined.map { CHARSET[it] }.joinToString("")
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}
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fun decode(input: String): Decoded {
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require(input.length in 8..90) { "Bech32 string has invalid length: ${input.length}" }
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require(input == input.lowercase() || input == input.uppercase()) { "Bech32 string is mixed case: $input" }
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val lower = input.lowercase()
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val separatorIndex = lower.lastIndexOf('1')
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require(separatorIndex >= 1) { "Bech32 string is missing separator '1': $input" }
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require(separatorIndex + 7 <= lower.length) { "Bech32 data part too short: $input" }
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val hrp = lower.substring(0, separatorIndex)
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val dataPart = lower.substring(separatorIndex + 1)
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val values = IntArray(dataPart.length)
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for ((i, c) in dataPart.withIndex()) {
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val v = CHARSET.indexOf(c)
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require(v >= 0) { "Invalid Bech32 character: '$c' in $input" }
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values[i] = v
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}
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val checksumValue = polymod(hrpExpand(hrp) + values)
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val encoding = when (checksumValue) {
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BECH32_CONST -> Encoding.BECH32
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BECH32M_CONST -> Encoding.BECH32M
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else -> throw IllegalArgumentException("Invalid Bech32/Bech32m checksum: $input")
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}
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return Decoded(hrp, values.copyOfRange(0, values.size - 6), encoding)
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}
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/**
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* Regroups bits between arbitrary group sizes (e.g. 8-bit bytes <-> 5-bit Bech32 words). Direct port of
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* BIP173's `convertbits`.
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*/
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fun convertBits(data: IntArray, fromBits: Int, toBits: Int, pad: Boolean): IntArray? {
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var acc = 0
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var bits = 0
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val ret = mutableListOf<Int>()
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val maxV = (1 shl toBits) - 1
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val maxAcc = (1 shl (fromBits + toBits - 1)) - 1
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for (value in data) {
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if (value < 0 || (value ushr fromBits) != 0) return null
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acc = ((acc shl fromBits) or value) and maxAcc
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bits += fromBits
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while (bits >= toBits) {
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bits -= toBits
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ret.add((acc ushr bits) and maxV)
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}
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}
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if (pad) {
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if (bits > 0) ret.add((acc shl (toBits - bits)) and maxV)
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} else if (bits >= fromBits || ((acc shl (toBits - bits)) and maxV) != 0) {
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return null
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}
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return ret.toIntArray()
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}
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}
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/**
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* Segwit address encoding/decoding (BIP173 witness v0, BIP350 witness v1+/Bech32m) on top of the raw [Bech32]
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* codec above. Only witness version 0 (P2WPKH/P2WSH) is actually used by this app today (native SegWit only -
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* Taproot/witness v1 is explicitly out of scope for now), but decode handles both since a user could paste any
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* valid segwit address.
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*/
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object SegwitAddress {
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fun encode(hrp: String, witnessVersion: Int, witnessProgram: ByteArray): String {
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require(witnessVersion in 0..16) { "Invalid witness version: $witnessVersion" }
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require(witnessProgram.size in 2..40) { "Invalid witness program length: ${witnessProgram.size}" }
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val programWords = Bech32.convertBits(witnessProgram.map { it.toInt() and 0xff }.toIntArray(), 8, 5, true)
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?: throw IllegalArgumentException("Failed to convert witness program to 5-bit words")
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val encoding = if (witnessVersion == 0) Bech32.Encoding.BECH32 else Bech32.Encoding.BECH32M
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return Bech32.encode(hrp, intArrayOf(witnessVersion) + programWords, encoding)
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}
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data class Decoded(val witnessVersion: Int, val witnessProgram: ByteArray)
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fun decode(expectedHrp: String, address: String): Decoded {
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val (hrp, values, encoding) = Bech32.decode(address)
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require(hrp == expectedHrp) { "Unexpected HRP: expected $expectedHrp, got $hrp" }
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require(values.isNotEmpty()) { "Empty Bech32 data part: $address" }
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val witnessVersion = values[0]
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val expectedEncoding = if (witnessVersion == 0) Bech32.Encoding.BECH32 else Bech32.Encoding.BECH32M
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require(encoding == expectedEncoding) {
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"Witness version $witnessVersion requires ${expectedEncoding.name} but address used ${encoding.name}: $address"
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}
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val programWords = values.copyOfRange(1, values.size)
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val programBytes = Bech32.convertBits(programWords, 5, 8, false)
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?: throw IllegalArgumentException("Invalid witness program padding: $address")
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require(programBytes.size in 2..40) { "Invalid witness program length: $address" }
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if (witnessVersion == 0) {
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require(programBytes.size == 20 || programBytes.size == 32) {
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"Witness v0 program must be 20 (P2WPKH) or 32 (P2WSH) bytes: $address"
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}
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}
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return Decoded(witnessVersion, ByteArray(programBytes.size) { programBytes[it].toByte() })
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}
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}
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@@ -0,0 +1,56 @@
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package io.novafoundation.nova.common.utils
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import io.novasama.substrate_sdk_android.runtime.AccountId
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import org.bouncycastle.jcajce.provider.digest.RIPEMD160
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/**
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* Native SegWit (P2WPKH) Bitcoin address support. Only witness v0 P2WPKH (`bc1q...`) is implemented - Taproot
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* and legacy/P2SH-SegWit are explicitly out of scope for this phase (see the BTC integration plan).
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*
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* Bitcoin's "account id" here is the 20-byte HASH160 of the compressed secp256k1 public key - unlike
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* Tron/Ethereum (which both derive their account id via keccak256 of the *uncompressed* pubkey), so this is
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* NOT interchangeable with [tronPublicKeyToAccountId]/`asEthereumPublicKey().toAccountId()` despite all three
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* using the same underlying secp256k1 keypair machinery.
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*/
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private const val BITCOIN_MAINNET_HRP = "bc"
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/** RIPEMD160(SHA256(x)) - the "HASH160" function used throughout Bitcoin for pubkey hashes and script hashes. */
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fun ByteArray.hash160(): ByteArray {
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val ripemd160 = RIPEMD160.Digest()
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return ripemd160.digest(this.sha256())
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}
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/**
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* @param compressedPublicKey a 33-byte compressed secp256k1 public key (0x02/0x03 prefix + 32-byte x-coordinate).
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*/
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fun ByteArray.bitcoinPublicKeyToAccountId(): AccountId {
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require(size == 33) { "Bitcoin native SegWit requires a compressed (33-byte) public key, got $size bytes" }
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return hash160()
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}
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/** P2WPKH scriptPubKey: `OP_0 <20-byte-push> <hash160>`, i.e. `0x00 0x14 <20 bytes>`. */
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fun AccountId.toP2wpkhScriptPubKey(): ByteArray {
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require(size == 20) { "Bitcoin account id (HASH160) must be 20 bytes, got $size" }
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return byteArrayOf(0x00, 0x14) + this
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}
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fun AccountId.toBitcoinAddress(): String {
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require(size == 20) { "Bitcoin account id (HASH160) must be 20 bytes, got $size" }
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return SegwitAddress.encode(BITCOIN_MAINNET_HRP, witnessVersion = 0, witnessProgram = this)
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}
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fun String.bitcoinAddressToAccountId(): AccountId {
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val decoded = SegwitAddress.decode(BITCOIN_MAINNET_HRP, this)
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require(decoded.witnessVersion == 0 && decoded.witnessProgram.size == 20) {
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"Not a native SegWit P2WPKH address: $this"
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}
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return decoded.witnessProgram
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}
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fun String.isValidBitcoinAddress(): Boolean = runCatching { bitcoinAddressToAccountId() }.isSuccess
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fun emptyBitcoinAccountId() = ByteArray(20) { 1 }
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@@ -0,0 +1,170 @@
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package io.novafoundation.nova.common.utils
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import java.io.ByteArrayOutputStream
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/** SHA256(SHA256(x)) - Bitcoin's standard "double SHA256", used for both txids and the BIP143 sighash. */
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fun ByteArray.sha256d(): ByteArray = sha256().sha256()
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/** Bitcoin's variable-length integer ("CompactSize") encoding, used throughout raw transaction serialization. */
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fun Long.toBitcoinVarInt(): ByteArray {
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require(this >= 0) { "VarInt cannot encode a negative value: $this" }
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val out = ByteArrayOutputStream()
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when {
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this < 0xfd -> out.write(toInt())
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this <= 0xffff -> {
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out.write(0xfd)
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out.write(toInt() and 0xff)
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out.write((toInt() ushr 8) and 0xff)
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}
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this <= 0xffffffffL -> {
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out.write(0xfe)
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for (i in 0..3) out.write(((this ushr (8 * i)) and 0xff).toInt())
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}
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else -> {
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out.write(0xff)
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for (i in 0..7) out.write(((this ushr (8 * i)) and 0xff).toInt())
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}
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}
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return out.toByteArray()
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}
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private fun Int.toLeBytes(byteCount: Int): ByteArray = ByteArray(byteCount) { i -> ((this ushr (8 * i)) and 0xff).toByte() }
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private fun Long.toLeBytes(byteCount: Int): ByteArray = ByteArray(byteCount) { i -> ((this ushr (8 * i)) and 0xff).toByte() }
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/**
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* A single UTXO being spent, in the form needed to build and sign a transaction.
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*
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* @param txid the previous transaction's id in standard (RPC/explorer-display) byte order - this class reverses
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* it internally to the on-wire/internal order raw transactions actually use (see [reversedTxid]).
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*/
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data class BitcoinInput(
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val txid: ByteArray,
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val vout: Int,
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val valueSat: Long,
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val sequence: Long = 0xfffffffdL, // RBF-signaling (BIP125), matching the exchange's proven, already-live choice
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) {
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init {
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require(txid.size == 32) { "txid must be 32 bytes, got ${txid.size}" }
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}
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fun reversedTxid(): ByteArray = txid.reversedArray()
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}
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data class BitcoinOutput(
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val valueSat: Long,
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val scriptPubKey: ByteArray,
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)
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/**
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* Builds and signs native SegWit (P2WPKH-only) Bitcoin transactions using BIP143 sighashes - hand-implemented
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* since no Bitcoin transaction library (bitcoinj/PSBT/etc.) is on this project's classpath (same rationale as
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* [Bech32]/[DerSignature]). Verified byte-for-byte against BIP143's official "Native P2WPKH" worked example,
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* including the fully serialized signed transaction - see [BitcoinTransactionTest].
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*/
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object BitcoinTransaction {
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private const val SIGHASH_ALL = 1
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/** P2PKH-shaped "scriptCode" BIP143 requires for a P2WPKH input - see BIP143's "Specification" section. */
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private fun p2wpkhScriptCode(accountId: ByteArray): ByteArray {
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require(accountId.size == 20)
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val script = byteArrayOf(0x76.toByte(), 0xa9.toByte(), 0x14) + accountId + byteArrayOf(0x88.toByte(), 0xac.toByte())
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return 25L.toBitcoinVarInt() + script
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}
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private fun serializeOutpoint(input: BitcoinInput): ByteArray = input.reversedTxid() + input.vout.toLeBytes(4)
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private fun hashPrevouts(inputs: List<BitcoinInput>): ByteArray =
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inputs.fold(ByteArray(0)) { acc, input -> acc + serializeOutpoint(input) }.sha256d()
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private fun hashSequence(inputs: List<BitcoinInput>): ByteArray =
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inputs.fold(ByteArray(0)) { acc, input -> acc + input.sequence.toLeBytes(4) }.sha256d()
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private fun serializeOutput(output: BitcoinOutput): ByteArray =
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output.valueSat.toLeBytes(8) + output.scriptPubKey.size.toLong().toBitcoinVarInt() + output.scriptPubKey
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private fun hashOutputs(outputs: List<BitcoinOutput>): ByteArray =
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outputs.fold(ByteArray(0)) { acc, output -> acc + serializeOutput(output) }.sha256d()
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/**
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* BIP143 sighash preimage + double-SHA256 for signing [inputIndex], which must be a P2WPKH input whose
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* pubkey hashes to [signingAccountId]. Always uses SIGHASH_ALL, no ANYONECANPAY/NONE/SINGLE - this app never
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* constructs those.
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*/
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fun bip143Sighash(
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version: Int,
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inputs: List<BitcoinInput>,
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outputs: List<BitcoinOutput>,
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inputIndex: Int,
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signingAccountId: ByteArray,
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locktime: Int,
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): ByteArray {
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val input = inputs[inputIndex]
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val preimage = version.toLeBytes(4) +
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hashPrevouts(inputs) +
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hashSequence(inputs) +
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serializeOutpoint(input) +
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p2wpkhScriptCode(signingAccountId) +
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input.valueSat.toLeBytes(8) +
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input.sequence.toLeBytes(4) +
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hashOutputs(outputs) +
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locktime.toLeBytes(4) +
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SIGHASH_ALL.toLeBytes(4)
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return preimage.sha256d()
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}
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/**
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* @param witnesses one (derSignatureWithoutSighashByte, compressedPublicKey) pair per input, in input order -
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* every input in this app's transactions is a P2WPKH input from this wallet's own single address, so every
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* witness has exactly 2 items (signature, pubkey), never a bare key-path/script-path Taproot witness or a
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* multisig-style stack.
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*/
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fun serializeSigned(
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version: Int,
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inputs: List<BitcoinInput>,
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outputs: List<BitcoinOutput>,
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witnesses: List<Pair<ByteArray, ByteArray>>,
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locktime: Int,
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): ByteArray {
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require(witnesses.size == inputs.size) { "Need exactly one witness per input" }
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val out = ByteArrayOutputStream()
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out.write(version.toLeBytes(4))
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out.write(0x00) // segwit marker
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out.write(0x01) // segwit flag
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out.write(inputs.size.toLong().toBitcoinVarInt())
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for (input in inputs) {
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out.write(input.reversedTxid())
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out.write(input.vout.toLeBytes(4))
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out.write(0L.toBitcoinVarInt()) // scriptSig: empty for a native SegWit input
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out.write(input.sequence.toLeBytes(4))
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}
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out.write(outputs.size.toLong().toBitcoinVarInt())
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for (output in outputs) {
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out.write(serializeOutput(output))
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}
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for ((derSignature, publicKey) in witnesses) {
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out.write(2L.toBitcoinVarInt()) // 2 witness items: signature, pubkey
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val sigWithHashType = derSignature + byteArrayOf(SIGHASH_ALL.toByte())
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out.write(sigWithHashType.size.toLong().toBitcoinVarInt())
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out.write(sigWithHashType)
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out.write(publicKey.size.toLong().toBitcoinVarInt())
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out.write(publicKey)
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}
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out.write(locktime.toLeBytes(4))
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return out.toByteArray()
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}
|
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|
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/**
|
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* Estimated virtual size in vbytes for fee purposes - the same hardcoded heuristic already proven in
|
||||
* production by `pezkuwi-exchange/wallet-service` (`inputs*68 + outputs*31 + 11`), reused here rather than
|
||||
* computing an exact post-signing weight (which would require knowing final DER signature lengths ahead of
|
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* time - low-S-normalized DER signatures are 70-72 bytes almost always, making this heuristic accurate to
|
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* within a few vbytes in practice).
|
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*/
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fun estimateVsize(inputCount: Int, outputCount: Int): Long = inputCount * 68L + outputCount * 31L + 11L
|
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}
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@@ -0,0 +1,62 @@
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package io.novafoundation.nova.common.utils
|
||||
|
||||
import java.math.BigInteger
|
||||
|
||||
/**
|
||||
* DER-encodes a raw secp256k1 ECDSA (r, s) signature the way Bitcoin's script/witness format requires it -
|
||||
* unlike Tron/Ethereum, which both use a fixed-size compact r(32)+s(32)+v(1) format (see
|
||||
* [io.novafoundation.nova.feature_wallet_impl.data.network.tron.transaction.RealTronTransactionService]'s
|
||||
* doc-comment for that format), Bitcoin signatures are a variable-length ASN.1 DER `SEQUENCE(INTEGER r, INTEGER
|
||||
* s)`.
|
||||
*
|
||||
* `r`/`s` are taken as raw big-endian unsigned 32-byte values - exactly what
|
||||
* [io.novasama.substrate_sdk_android]'s `SignatureWrapper.Ecdsa` (reached via `SignedRaw.toEcdsaSignatureData()`)
|
||||
* already exposes for Ethereum-style signing, which this app already uses. No new signing call path is needed
|
||||
* for Bitcoin: only this pure, standalone encoding step is new.
|
||||
*/
|
||||
object DerSignature {
|
||||
|
||||
// secp256k1 curve order n, and n/2 - Bitcoin Core's standardness rules (BIP62) reject a signature whose `s`
|
||||
// is greater than n/2 ("high-S"); wallets are expected to always produce the "low-S" of the two equally
|
||||
// valid (r, s) and (r, n-s) signatures for a given message, or relay nodes/miners may refuse the transaction.
|
||||
private val CURVE_ORDER = BigInteger("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141", 16)
|
||||
private val HALF_CURVE_ORDER = CURVE_ORDER.shiftRight(1)
|
||||
|
||||
/**
|
||||
* @param r raw big-endian unsigned 32-byte value
|
||||
* @param s raw big-endian unsigned 32-byte value (will be normalized to low-S if not already)
|
||||
* @return DER-encoded `SEQUENCE(INTEGER r, INTEGER s)`, WITHOUT the trailing sighash-type byte (the caller
|
||||
* appends that when assembling the witness/scriptSig, since it is not part of the DER signature itself).
|
||||
*/
|
||||
fun encode(r: ByteArray, s: ByteArray): ByteArray {
|
||||
val rInt = BigInteger(1, r)
|
||||
var sInt = BigInteger(1, s)
|
||||
|
||||
if (sInt > HALF_CURVE_ORDER) {
|
||||
sInt = CURVE_ORDER.subtract(sInt)
|
||||
}
|
||||
|
||||
val rEncoded = encodeInteger(rInt)
|
||||
val sEncoded = encodeInteger(sInt)
|
||||
|
||||
val sequenceBody = rEncoded + sEncoded
|
||||
|
||||
return byteArrayOf(0x30, sequenceBody.size.toDerLength()) + sequenceBody
|
||||
}
|
||||
|
||||
/**
|
||||
* ASN.1 DER INTEGER: tag(0x02) + length + minimal big-endian two's-complement bytes. [BigInteger.toByteArray]
|
||||
* already produces minimal big-endian two's-complement (including the leading 0x00 disambiguation byte when
|
||||
* the high bit of the first byte would otherwise be set, which would make it read as negative) - since
|
||||
* `rInt`/`sInt` are always non-negative here, its output is exactly the DER INTEGER content we need.
|
||||
*/
|
||||
private fun encodeInteger(value: BigInteger): ByteArray {
|
||||
val bytes = value.toByteArray()
|
||||
return byteArrayOf(0x02, bytes.size.toDerLength()) + bytes
|
||||
}
|
||||
|
||||
private fun Int.toDerLength(): Byte {
|
||||
require(this in 0..127) { "DER length $this requires long-form encoding, not expected for a 32-byte ECDSA signature" }
|
||||
return toByte()
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user