AND-8609: Add CasperAddressService

blockchain/src/main/java/com/tangem/blockchain/blockchains/casper/CasperAddressService.kt

@@ -0,0 +1,33 @@
+package com.tangem.blockchain.blockchains.casper
+
+import com.tangem.blockchain.blockchains.casper.cashaddr.CasperAddressUtils.checksum
+import com.tangem.blockchain.common.address.AddressService
+import com.tangem.blockchain.extensions.isSameCase
+import com.tangem.common.card.EllipticCurve
+import com.tangem.common.extensions.hexToBytes
+
+internal class CasperAddressService : AddressService() {
+    override fun makeAddress(walletPublicKey: ByteArray, curve: EllipticCurve?): String {
+        val prefix = CasperConstants.getAddressPrefix(curve!!)
+        val bytes = prefix.hexToBytes() + walletPublicKey
+        return bytes.checksum()
+    }
+
+    override fun validate(address: String): Boolean {
+        val isCorrectEd25519Address = address.length == CasperConstants.ED25519_LENGTH &&
+            address.startsWith(CasperConstants.ED25519_PREFIX)
+        val isCorrectSecp256k1Address = address.length == CasperConstants.SECP256K1_LENGTH &&
+            address.startsWith(CasperConstants.SECP256K1_PREFIX)
+
+        if (!isCorrectEd25519Address && !isCorrectSecp256k1Address) {
+            return false
+        }
+
+        // don't check checksum if it's not mixed case
+        if (address.isSameCase()) {
+            return true
+        }
+
+        return address == address.hexToBytes().checksum()
+    }
+}

blockchain/src/main/java/com/tangem/blockchain/blockchains/casper/CasperConstants.kt

@@ -0,0 +1,26 @@
+package com.tangem.blockchain.blockchains.casper
+
+import com.tangem.common.card.EllipticCurve
+
+internal object CasperConstants {
+    const val ED25519_PREFIX = "01"
+    const val ED25519_LENGTH = 66
+
+    const val SECP256K1_PREFIX = "02"
+    const val SECP256K1_LENGTH = 68
+
+    fun getAddressPrefix(curve: EllipticCurve) = when (curve) {
+        EllipticCurve.Ed25519,
+        EllipticCurve.Ed25519Slip0010,
+        -> ED25519_PREFIX
+        EllipticCurve.Secp256k1,
+        -> SECP256K1_PREFIX
+        // added as unsupported for now, need to research
+        EllipticCurve.Secp256r1,
+        EllipticCurve.Bls12381G2,
+        EllipticCurve.Bls12381G2Aug,
+        EllipticCurve.Bls12381G2Pop,
+        EllipticCurve.Bip0340,
+        -> error("${curve.curve} is not supported")
+    }
+}

blockchain/src/main/java/com/tangem/blockchain/blockchains/casper/cashaddr/CasperAddressUtils.kt

@@ -0,0 +1,55 @@
+package com.tangem.blockchain.blockchains.casper.cashaddr
+
+import org.bouncycastle.jcajce.provider.digest.Blake2b
+
+/**
+ * @see <a href="https://github.com/casper-ecosystem/casper-js-sdk/blob/dev/src/lib/ChecksummedHex.ts">Source</a>
+ */
+object CasperAddressUtils {
+    // Ed25519: encode([0x01]) + encode(<public key bytes>)
+    // or
+    // Secp256k1: encode([0x02]) + encode(<public key bytes>)
+    fun ByteArray.checksum(): String = encode(byteArrayOf(first())) + encode(drop(1).toByteArray())
+
+    // Separate bytes inside ByteArray to nibbles
+    // E.g. [0x01, 0x55, 0xFF, ...] -> [0x00, 0x01, 0x50, 0x05, 0xF0, 0x0F, ...]
+    @Suppress("MagicNumber")
+    private fun bytesToNibbles(bytes: ByteArray): ByteArray = bytes
+        .flatMap { byte ->
+            listOf(
+                (byte.toInt() and 0xff shr 4).toByte(),
+                (byte.toInt() and 0x0f).toByte(),
+            )
+        }.toByteArray()
+
+    // Separate bytes inside ByteArray to bits array
+    // E.g. [0x01, ...] -> [false, false, false, false, false, false, false, true, ...]
+    // E.g. [0xAA, ...] -> [true, false, true, false, true, false, true, false, ...]
+    @Suppress("MagicNumber")
+    private fun ByteArray.toBitArray(): BooleanArray = this
+        .flatMap { byte ->
+            List(8) { i ->
+                byte.toInt() shr i and 0x01 == 0x01
+            }
+        }.toBooleanArray()
+
+    private fun byteHash(bytes: ByteArray): ByteArray = Blake2b.Blake2b256().digest(bytes)
+
+    private fun encode(input: ByteArray): String {
+        val inputNibbles = bytesToNibbles(input)
+        val hash = byteHash(input)
+        val hashBits = hash.toBitArray()
+        val hashBitsValues = hashBits.iterator()
+        val hexOutputString = inputNibbles.fold(StringBuilder()) { accum, nibble ->
+            val c = "%x".format(nibble)
+
+            if (Regex("^[a-zA-Z()]+\$").matches(c) && hashBitsValues.hasNext() && hashBitsValues.next()) {
+                accum.append(c.uppercase())
+            } else {
+                accum.append(c.lowercase())
+            }
+            accum
+        }.toString()
+        return hexOutputString
+    }
+}

blockchain/src/main/java/com/tangem/blockchain/common/Blockchain.kt

@@ -5,6 +5,7 @@ import com.tangem.blockchain.blockchains.binance.BinanceAddressService
 import com.tangem.blockchain.blockchains.bitcoin.BitcoinAddressService
 import com.tangem.blockchain.blockchains.bitcoincash.BitcoinCashAddressService
 import com.tangem.blockchain.blockchains.cardano.CardanoAddressServiceFacade
+import com.tangem.blockchain.blockchains.casper.CasperAddressService
 import com.tangem.blockchain.blockchains.chia.ChiaAddressService
 import com.tangem.blockchain.blockchains.decimal.DecimalAddressService
 import com.tangem.blockchain.blockchains.ethereum.Chain
@@ -377,7 +378,7 @@ enum class Blockchain(
             Nexa, NexaTestnet -> NexaAddressService(this.isTestnet())
             Koinos, KoinosTestnet -> KoinosAddressService()
             Radiant -> RadiantAddressService()
-            Casper, CasperTestnet -> TODO() // AND-8609
+            Casper, CasperTestnet -> CasperAddressService()
             Unknown -> error("unsupported blockchain")
         }
     }

blockchain/src/main/java/com/tangem/blockchain/extensions/String.kt

@@ -38,6 +38,8 @@ fun String?.toBigDecimalOrDefault(default: BigDecimal = BigDecimal.ZERO): BigDec
 
 fun String.isValidHex(): Boolean = this.all { it.isAscii() }
 
+fun String.isSameCase(): Boolean = this.lowercase() == this || this.uppercase() == this
+
 inline fun <R> String?.letNotBlank(block: (String) -> R): R? {
     if (isNullOrBlank()) return null
 

blockchain/src/test/java/com/tangem/blockchain/blockchains/casper/CasperAddressTest.kt

@@ -0,0 +1,41 @@
+package com.tangem.blockchain.blockchains.casper
+
+import com.google.common.truth.Truth
+import com.tangem.common.card.EllipticCurve
+import com.tangem.common.extensions.hexToBytes
+import org.junit.Test
+
+class CasperAddressTest {
+
+    private val addressService = CasperAddressService()
+
+    @Test
+    fun makeAddressFromCorrectEd25519PublicKey() {
+        val walletPublicKey = "98C07D7E72D89A681D7227A7AF8A6FD5F22FE0105C8741D55A95DF415454B82E".hexToBytes()
+        val expected = "0198c07D7e72D89A681d7227a7Af8A6fd5F22fe0105c8741d55A95dF415454b82E"
+
+        Truth.assertThat(addressService.makeAddress(walletPublicKey, EllipticCurve.Ed25519)).isEqualTo(expected)
+    }
+
+    @Test
+    fun validateCorrectEd25519Address() {
+        val address = "0198c07D7e72D89A681d7227a7Af8A6fd5F22fe0105c8741d55A95dF415454b82E"
+
+        Truth.assertThat(addressService.validate(address)).isTrue()
+    }
+
+    @Test
+    fun makeAddressFromCorrectSecp256k1PublicKey() {
+        val walletPublicKey = "021F997DFBBFD32817C0E110EAEE26BCBD2BB70B4640C515D9721C9664312EACD8".hexToBytes()
+        val expected = "02021f997DfbbFd32817C0E110EAeE26BCbD2BB70b4640C515D9721c9664312eaCd8"
+
+        Truth.assertThat(addressService.makeAddress(walletPublicKey, EllipticCurve.Secp256k1)).isEqualTo(expected)
+    }
+
+    @Test
+    fun validateCorrectSecp256k1Address() {
+        val address = "02021f997DfbbFd32817C0E110EAeE26BCbD2BB70b4640C515D9721c9664312eaCd8"
+
+        Truth.assertThat(addressService.validate(address)).isTrue()
+    }
+}