Btc subfamily alt with different hashing

altchain-plugins/src/main/kotlin/org/veriblock/alt/plugins/bitcoin/BitcoinFamilyChain.kt

@@ -49,7 +49,7 @@ private val logger = createLogger {}
 private const val NOT_FOUND_ERROR_CODE = -5
 
 @PluginSpec(name = "BitcoinFamily", key = "btc")
-class BitcoinFamilyChain(
+open class BitcoinFamilyChain(
     override val key: String,
     configuration: PluginConfig
 ) : HttpSecurityInheritingChain {
@@ -287,7 +287,7 @@ class BitcoinFamilyChain(
             val witnessProgram = ByteArray(addressData.size - 2)
             addressData.copyInto(witnessProgram, 0,2, addressData.size)
             try {
-                segwitToBech32(config.addressPrefix,0, witnessProgram)
+                segwitToBech32(config.addressPrefix!!,0, witnessProgram)
             } catch (exception: Exception) {
                 throw IllegalArgumentException("Can't extract the Bech32 address from the address data: ${addressData.toHex()}", exception)
             }
@@ -387,12 +387,12 @@ class BitcoinFamilyChain(
         checkNotNull(config.payoutAddress) {
             "$name's payoutAddress ($key.payoutAddress) must be configured!"
         }
-        if (config.payoutAddress.isEmpty() || config.payoutAddress == "INSERT PAYOUT ADDRESS") {
+        if (config.payoutAddress?.isEmpty() == true || config.payoutAddress == "INSERT PAYOUT ADDRESS") {
             error(
                 "'${config.payoutAddress}' is not a valid value for the $name's payoutAddress configuration ($key.payoutAddress). Please set up a valid payout address"
             )
         }
-        payoutAddress = config.payoutAddress
+        payoutAddress = config.payoutAddress!!
     }
 
     private suspend fun validateAddress(address: String): ByteArray {

altchain-plugins/src/main/kotlin/org/veriblock/alt/plugins/bitcoin/PexaFamilyChain.kt

@@ -0,0 +1,38 @@
+// VeriBlock Blockchain Project
+// Copyright 2017-2018 VeriBlock, Inc
+// Copyright 2018-2021 Xenios SEZC
+// All rights reserved.
+// https://www.veriblock.org
+// Distributed under the MIT software license, see the accompanying
+// file LICENSE or http://www.opensource.org/licenses/mit-license.php.
+
+package org.veriblock.alt.plugins.bitcoin
+
+import org.veriblock.core.altchain.AltchainPoPEndorsement
+import org.veriblock.core.contracts.BlockEvidence
+import org.veriblock.core.crypto.*
+import org.veriblock.core.utilities.SerializerUtility
+import org.veriblock.core.utilities.extensions.flip
+import org.veriblock.sdk.alt.plugin.PluginConfig
+import org.veriblock.sdk.alt.plugin.PluginSpec
+import java.nio.ByteBuffer
+
+@PluginSpec(name = "PexaFamily", key = "phx")
+class PexaFamilyChain(
+    override val key: String,
+    configuration: PluginConfig
+) : BitcoinFamilyChain(key, configuration) {
+
+    private val crypto = Crypto()
+
+    override fun extractBlockEvidence(altchainPopEndorsement: AltchainPoPEndorsement): BlockEvidence {
+        val hash = crypto.SHA256D(altchainPopEndorsement.getHeader()).flip()
+        val previousHash = altchainPopEndorsement.getHeader().copyOfRange(4, 36).flip()
+        val contextBuffer = ByteBuffer.wrap(altchainPopEndorsement.getContextInfo())
+        val height = contextBuffer.getInt()
+        val previousKeystone = SerializerUtility.readSingleByteLenValue(contextBuffer, 8, 64).flip()
+        val secondPreviousKeystone = SerializerUtility.readSingleByteLenValue(contextBuffer, 8, 64).flip()
+
+        return BlockEvidence(height, hash, previousHash, previousKeystone, secondPreviousKeystone)
+    }
+}