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Add member methods to improve usability (#132)
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Add member methods to improve usability

Member methods (in addition to static methods) will make this library easier to use, especially from IDE/editors that implement code completion features.
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@sstone
sstone authored Aug 20, 2024
1 parent bc2d1e4 commit e52c575
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Showing 4 changed files with 537 additions and 290 deletions.
42 changes: 32 additions & 10 deletions src/commonMain/kotlin/fr/acinq/bitcoin/Block.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,28 @@ public data class BlockHeader(

public fun setNonce(input: Long): BlockHeader = this.copy(nonce = input)

public fun difficulty(): UInt256 {
val (diff, neg, _) = UInt256.decodeCompact(bits)
return if (neg) -diff else diff
}

/**
*
* @return the amount of work represented by this block's difficulty target, as displayed by bitcoin core
*/
public fun blockProof(): UInt256 = blockProof(bits)

/**
* Proof of work: hash(header) <= target difficulty
*
* @return true if this block header validates its expected proof of work
*/
public fun checkProofOfWork(): Boolean {
val (target, _, _) = UInt256.decodeCompact(bits)
val hash = UInt256(blockId.value.toByteArray())
return hash <= target
}

@Suppress("PARAMETER_NAME_CHANGED_ON_OVERRIDE")
public companion object : BtcSerializer<BlockHeader>() {
override fun read(input: Input, protocolVersion: Long): BlockHeader {
Expand Down Expand Up @@ -120,10 +142,7 @@ public data class BlockHeader(
}

@JvmStatic
public fun getDifficulty(header: BlockHeader): UInt256 {
val (diff, neg, _) = UInt256.decodeCompact(header.bits)
return if (neg) -diff else diff
}
public fun getDifficulty(header: BlockHeader): UInt256 = header.difficulty()

/**
*
Expand Down Expand Up @@ -152,11 +171,7 @@ public data class BlockHeader(
* @return true if the input block header validates its expected proof of work
*/
@JvmStatic
public fun checkProofOfWork(header: BlockHeader): Boolean {
val (target, _, _) = UInt256.decodeCompact(header.bits)
val hash = UInt256(header.blockId.value.toByteArray())
return hash <= target
}
public fun checkProofOfWork(header: BlockHeader): Boolean = header.checkProofOfWork()

@JvmStatic
public fun calculateNextWorkRequired(lastHeader: BlockHeader, lastRetargetTime: Long): Long {
Expand Down Expand Up @@ -208,6 +223,13 @@ public data class Block(@JvmField val header: BlockHeader, @JvmField val tx: Lis
@JvmField
val blockId: BlockId = header.blockId

/**
* Proof of work: hash(block) <= target difficulty
*
* @return true if the input block validates its expected proof of work
*/
public fun checkProofOfWork(): Boolean = BlockHeader.checkProofOfWork(header)

public companion object : BtcSerializer<Block>() {
override fun write(message: Block, out: Output, protocolVersion: Long) {
BlockHeader.write(message.header, out)
Expand Down Expand Up @@ -250,7 +272,7 @@ public data class Block(@JvmField val header: BlockHeader, @JvmField val tx: Lis
* @return true if the input block validates its expected proof of work
*/
@JvmStatic
public fun checkProofOfWork(block: Block): Boolean = BlockHeader.checkProofOfWork(block.header)
public fun checkProofOfWork(block: Block): Boolean = block.checkProofOfWork()

/**
* Verify a tx inclusion proof (a merkle proof that a set of transactions are included in a given block)
Expand Down
196 changes: 113 additions & 83 deletions src/commonMain/kotlin/fr/acinq/bitcoin/DeterministicWallet.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,56 @@ public object DeterministicWallet {

val privateKey: PrivateKey get() = PrivateKey(secretkeybytes)
val publicKey: PublicKey get() = privateKey.publicKey()
val extendedPublicKey: ExtendedPublicKey get() = ExtendedPublicKey(publicKey.value, chaincode, depth = depth, path = path, parent = parent)

/**
* @param index index of the child key
* @return the derived private key at the specified index
*/
public fun derivePrivateKey(index: Long): ExtendedPrivateKey {
val I = if (isHardened(index)) {
val data = arrayOf(0.toByte()).toByteArray() + secretkeybytes.toByteArray() + Pack.writeInt32BE(index.toInt())
Crypto.hmac512(chaincode.toByteArray(), data)
} else {
val data = extendedPublicKey.publickeybytes.toByteArray() + Pack.writeInt32BE(index.toInt())
Crypto.hmac512(chaincode.toByteArray(), data)
}
val IL = I.take(32).toByteArray()
val IR = I.takeLast(32).toByteArray()
require(Crypto.isPrivKeyValid(IL)) { "cannot generate child private key: IL is invalid" }

val key = PrivateKey(IL) + privateKey
require(Crypto.isPrivKeyValid(key.value.toByteArray())) { "cannot generate child private key: resulting private key is invalid" }
return ExtendedPrivateKey(
secretkeybytes = key.value,
chaincode = IR.byteVector32(),
depth = depth + 1,
path = path.derive(index),
parent = fingerprint()
)
}

public fun derivePrivateKey(chain: List<Long>): ExtendedPrivateKey = chain.fold(this) { k, i -> k.derivePrivateKey(i) }

public fun derivePrivateKey(keyPath: KeyPath): ExtendedPrivateKey = derivePrivateKey(keyPath.path)

public fun derivePrivateKey(keyPath: String): ExtendedPrivateKey = derivePrivateKey(KeyPath.fromPath(keyPath))

public fun encode(testnet: Boolean): String = this.encode(if (testnet) tprv else xprv)

public fun encode(prefix: Int): String {
val out = ByteArrayOutput()
out.write(depth)
Pack.writeInt32BE(parent.toInt(), out)
Pack.writeInt32BE(path.lastChildNumber.toInt(), out)
out.write(chaincode.toByteArray())
out.write(0)
out.write(secretkeybytes.toByteArray())
val buffer = out.toByteArray()
return Base58Check.encode(prefix, buffer)
}

public fun fingerprint(): Long = extendedPublicKey.fingerprint()

/**
* We avoid accidentally logging extended private keys.
Expand Down Expand Up @@ -93,6 +143,56 @@ public object DeterministicWallet {

val publicKey: PublicKey get() = PublicKey(publickeybytes)

/**
* @param index index of the child key
* @return the derived public key at the specified index
*/
public fun derivePublicKey(index: Long): ExtendedPublicKey {
require(!isHardened(index)) { "Cannot derive public keys from public hardened keys" }

val I = Crypto.hmac512(
chaincode.toByteArray(), publickeybytes.toByteArray() + Pack.writeInt32BE(index.toInt())
)
val IL = I.take(32).toByteArray()
val IR = I.takeLast(32).toByteArray()
require(Crypto.isPrivKeyValid(IL)) { "cannot generate child public key: IL is invalid" }

val Ki = PrivateKey(IL).publicKey() + publicKey
require(Crypto.isPubKeyValid(Ki.value.toByteArray())) { "cannot generate child public key: resulting public key is invalid" }
return ExtendedPublicKey(
publickeybytes = Ki.value,
chaincode = IR.byteVector32(),
depth = depth + 1,
path = path.derive(index),
parent = fingerprint()
)
}

public fun derivePublicKey(chain: List<Long>): ExtendedPublicKey = chain.fold(this) { k, i -> k.derivePublicKey(i) }

public fun derivePublicKey(keyPath: KeyPath): ExtendedPublicKey = derivePublicKey(keyPath.path)

public fun derivePublicKey(keyPath: String): ExtendedPublicKey = derivePublicKey(KeyPath.fromPath(keyPath))

public fun fingerprint(): Long = Pack.int32LE(ByteArrayInput(Crypto.hash160(publickeybytes).take(4).reversed().toByteArray())).toLong()

public fun encode(prefix: Int): String {
val out = ByteArrayOutput()
this.write(out)
val buffer = out.toByteArray()
return Base58Check.encode(prefix, buffer)
}

public fun encode(testnet: Boolean): String = encode(if (testnet) tpub else xpub)

public fun write(out: Output) {
out.write(depth)
Pack.writeInt32BE(parent.toInt(), out)
Pack.writeInt32BE(path.lastChildNumber.toInt(), out)
out.write(chaincode.toByteArray())
out.write(publickeybytes.toByteArray())
}

public companion object {
@JvmStatic
public fun decode(input: String, parentPath: KeyPath = KeyPath.empty): Pair<Int, ExtendedPublicKey> {
Expand All @@ -115,37 +215,16 @@ public object DeterministicWallet {
public fun encode(input: ExtendedPrivateKey, testnet: Boolean): String = encode(input, if (testnet) tprv else xprv)

@JvmStatic
public fun encode(input: ExtendedPrivateKey, prefix: Int): String {
val out = ByteArrayOutput()
out.write(input.depth)
Pack.writeInt32BE(input.parent.toInt(), out)
Pack.writeInt32BE(input.path.lastChildNumber.toInt(), out)
out.write(input.chaincode.toByteArray())
out.write(0)
out.write(input.secretkeybytes.toByteArray())
val buffer = out.toByteArray()
return Base58Check.encode(prefix, buffer)
}
public fun encode(input: ExtendedPrivateKey, prefix: Int): String = input.encode(prefix)

@JvmStatic
public fun encode(input: ExtendedPublicKey, testnet: Boolean): String = encode(input, if (testnet) tpub else xpub)

@JvmStatic
public fun encode(input: ExtendedPublicKey, prefix: Int): String {
val out = ByteArrayOutput()
write(input, out)
val buffer = out.toByteArray()
return Base58Check.encode(prefix, buffer)
}
public fun encode(input: ExtendedPublicKey, prefix: Int): String = input.encode(prefix)

@JvmStatic
public fun write(input: ExtendedPublicKey, out: Output) {
out.write(input.depth)
Pack.writeInt32BE(input.parent.toInt(), out)
Pack.writeInt32BE(input.path.lastChildNumber.toInt(), out)
out.write(input.chaincode.toByteArray())
out.write(input.publickeybytes.toByteArray())
}
public fun write(input: ExtendedPublicKey, out: Output): Unit = input.write(out)

/**
* @param seed random seed
Expand All @@ -171,16 +250,14 @@ public object DeterministicWallet {
* @return the public key for this private key
*/
@JvmStatic
public fun publicKey(input: ExtendedPrivateKey): ExtendedPublicKey {
return ExtendedPublicKey(input.publicKey.value, input.chaincode, depth = input.depth, path = input.path, parent = input.parent)
}
public fun publicKey(input: ExtendedPrivateKey): ExtendedPublicKey = input.extendedPublicKey

/**
* @param input extended public key
* @return the fingerprint for this public key
*/
@JvmStatic
public fun fingerprint(input: ExtendedPublicKey): Long = Pack.int32LE(ByteArrayInput(Crypto.hash160(input.publickeybytes).take(4).reversed().toByteArray())).toLong()
public fun fingerprint(input: ExtendedPublicKey): Long = input.fingerprint()

/**
* @param input extended private key
Expand All @@ -195,80 +272,33 @@ public object DeterministicWallet {
* @return the derived private key at the specified index
*/
@JvmStatic
public fun derivePrivateKey(parent: ExtendedPrivateKey, index: Long): ExtendedPrivateKey {
val I = if (isHardened(index)) {
val data = arrayOf(0.toByte()).toByteArray() + parent.secretkeybytes.toByteArray() + Pack.writeInt32BE(index.toInt())
Crypto.hmac512(parent.chaincode.toByteArray(), data)
} else {
val data = publicKey(parent).publickeybytes.toByteArray() + Pack.writeInt32BE(index.toInt())
Crypto.hmac512(parent.chaincode.toByteArray(), data)
}
val IL = I.take(32).toByteArray()
val IR = I.takeLast(32).toByteArray()
require(Crypto.isPrivKeyValid(IL)) { "cannot generate child private key: IL is invalid" }

val key = PrivateKey(IL) + parent.privateKey
require(Crypto.isPrivKeyValid(key.value.toByteArray())) { "cannot generate child private key: resulting private key is invalid" }
return ExtendedPrivateKey(
secretkeybytes = key.value,
chaincode = IR.byteVector32(),
depth = parent.depth + 1,
path = parent.path.derive(index),
parent = fingerprint(parent)
)
}
public fun derivePrivateKey(parent: ExtendedPrivateKey, index: Long): ExtendedPrivateKey = parent.derivePrivateKey(index)

/**
* @param parent extended public key
* @param index index of the child key
* @return the derived public key at the specified index
*/
@JvmStatic
public fun derivePublicKey(parent: ExtendedPublicKey, index: Long): ExtendedPublicKey {
require(!isHardened(index)) { "Cannot derive public keys from public hardened keys" }

val I = Crypto.hmac512(
parent.chaincode.toByteArray(),
parent.publickeybytes.toByteArray() + Pack.writeInt32BE(index.toInt())
)
val IL = I.take(32).toByteArray()
val IR = I.takeLast(32).toByteArray()
require(Crypto.isPrivKeyValid(IL)) { "cannot generate child public key: IL is invalid" }

val Ki = PrivateKey(IL).publicKey() + parent.publicKey
require(Crypto.isPubKeyValid(Ki.value.toByteArray())) { "cannot generate child public key: resulting public key is invalid" }
return ExtendedPublicKey(
publickeybytes = Ki.value,
chaincode = IR.byteVector32(),
depth = parent.depth + 1,
path = parent.path.derive(index),
parent = fingerprint(parent)
)
}
public fun derivePublicKey(parent: ExtendedPublicKey, index: Long): ExtendedPublicKey = parent.derivePublicKey(index)

@JvmStatic
public fun derivePrivateKey(parent: ExtendedPrivateKey, chain: List<Long>): ExtendedPrivateKey =
chain.fold(parent, DeterministicWallet::derivePrivateKey)
public fun derivePrivateKey(parent: ExtendedPrivateKey, chain: List<Long>): ExtendedPrivateKey = parent.derivePrivateKey(chain)

@JvmStatic
public fun derivePrivateKey(parent: ExtendedPrivateKey, keyPath: KeyPath): ExtendedPrivateKey =
derivePrivateKey(parent, keyPath.path)
public fun derivePrivateKey(parent: ExtendedPrivateKey, keyPath: KeyPath): ExtendedPrivateKey = parent.derivePrivateKey(keyPath.path)

@JvmStatic
public fun derivePrivateKey(parent: ExtendedPrivateKey, keyPath: String): ExtendedPrivateKey =
derivePrivateKey(parent, KeyPath.fromPath(keyPath))
public fun derivePrivateKey(parent: ExtendedPrivateKey, keyPath: String): ExtendedPrivateKey = parent.derivePrivateKey(KeyPath.fromPath(keyPath))

@JvmStatic
public fun derivePublicKey(parent: ExtendedPublicKey, chain: List<Long>): ExtendedPublicKey =
chain.fold(parent, DeterministicWallet::derivePublicKey)
public fun derivePublicKey(parent: ExtendedPublicKey, chain: List<Long>): ExtendedPublicKey = parent.derivePublicKey(chain)

@JvmStatic
public fun derivePublicKey(parent: ExtendedPublicKey, keyPath: KeyPath): ExtendedPublicKey =
derivePublicKey(parent, keyPath.path)
public fun derivePublicKey(parent: ExtendedPublicKey, keyPath: KeyPath): ExtendedPublicKey = parent.derivePublicKey(keyPath.path)

@JvmStatic
public fun derivePublicKey(parent: ExtendedPublicKey, keyPath: String): ExtendedPublicKey =
derivePublicKey(parent, KeyPath.fromPath(keyPath))
public fun derivePublicKey(parent: ExtendedPublicKey, keyPath: String): ExtendedPublicKey = parent.derivePublicKey(KeyPath.fromPath(keyPath))

// p2pkh mainnet
public const val xprv: Int = 0x0488ade4
Expand Down
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