Use LegacyZcashAddress (copied and modified from bitcoinj) to derive and encode Pirate Chain P2SH addresses.

It wasn't possible to use bitcoinj directly because Zcash-style P2SH addresses have 2 prefix characters (t3), which isn't supported by bitcoinj.

src/main/java/org/qortal/crosschain/LegacyZcashAddress.java

@@ -0,0 +1,254 @@
+/*
+ * Copyright 2011 Google Inc.
+ * Copyright 2014 Giannis Dzegoutanis
+ * Copyright 2015 Andreas Schildbach
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Updated for Zcash in May 2022 by Qortal core dev team. Modifications allow
+* correct encoding of P2SH (t3) addresses only. */
+
+package org.qortal.crosschain;
+
+import org.bitcoinj.core.*;
+import org.bitcoinj.params.Networks;
+import org.bitcoinj.script.Script.ScriptType;
+
+import javax.annotation.Nullable;
+import java.util.Arrays;
+import java.util.Objects;
+
+/**
+ * <p>A Bitcoin address looks like 1MsScoe2fTJoq4ZPdQgqyhgWeoNamYPevy and is derived from an elliptic curve public key
+ * plus a set of network parameters. Not to be confused with a {@link PeerAddress} or {@link AddressMessage}
+ * which are about network (TCP) addresses.</p>
+ *
+ * <p>A standard address is built by taking the RIPE-MD160 hash of the public key bytes, with a version prefix and a
+ * checksum suffix, then encoding it textually as base58. The version prefix is used to both denote the network for
+ * which the address is valid (see {@link NetworkParameters}, and also to indicate how the bytes inside the address
+ * should be interpreted. Whilst almost all addresses today are hashes of public keys, another (currently unsupported
+ * type) can contain a hash of a script instead.</p>
+ */
+public class LegacyZcashAddress extends Address {
+    /**
+     * An address is a RIPEMD160 hash of a public key, therefore is always 160 bits or 20 bytes.
+     */
+    public static final int LENGTH = 20;
+
+    /** True if P2SH, false if P2PKH. */
+    public final boolean p2sh;
+
+    /* Zcash P2SH header bytes */
+    private static int P2SH_HEADER_1 = 28;
+    private static int P2SH_HEADER_2 = 189;
+
+    /**
+     * Private constructor. Use {@link #fromBase58(NetworkParameters, String)},
+     * {@link #fromPubKeyHash(NetworkParameters, byte[])}, {@link #fromScriptHash(NetworkParameters, byte[])} or
+     * {@link #fromKey(NetworkParameters, ECKey)}.
+     * 
+     * @param params
+     *            network this address is valid for
+     * @param p2sh
+     *            true if hash160 is hash of a script, false if it is hash of a pubkey
+     * @param hash160
+     *            20-byte hash of pubkey or script
+     */
+    private LegacyZcashAddress(NetworkParameters params, boolean p2sh, byte[] hash160) throws AddressFormatException {
+        super(params, hash160);
+        if (hash160.length != 20)
+            throw new AddressFormatException.InvalidDataLength(
+                    "Legacy addresses are 20 byte (160 bit) hashes, but got: " + hash160.length);
+        this.p2sh = p2sh;
+    }
+
+    /**
+     * Construct a {@link LegacyZcashAddress} that represents the given pubkey hash. The resulting address will be a P2PKH type of
+     * address.
+     * 
+     * @param params
+     *            network this address is valid for
+     * @param hash160
+     *            20-byte pubkey hash
+     * @return constructed address
+     */
+    public static LegacyZcashAddress fromPubKeyHash(NetworkParameters params, byte[] hash160) throws AddressFormatException {
+        return new LegacyZcashAddress(params, false, hash160);
+    }
+
+    /**
+     * Construct a {@link LegacyZcashAddress} that represents the public part of the given {@link ECKey}. Note that an address is
+     * derived from a hash of the public key and is not the public key itself.
+     * 
+     * @param params
+     *            network this address is valid for
+     * @param key
+     *            only the public part is used
+     * @return constructed address
+     */
+    public static LegacyZcashAddress fromKey(NetworkParameters params, ECKey key) {
+        return fromPubKeyHash(params, key.getPubKeyHash());
+    }
+
+    /**
+     * Construct a {@link LegacyZcashAddress} that represents the given P2SH script hash.
+     * 
+     * @param params
+     *            network this address is valid for
+     * @param hash160
+     *            P2SH script hash
+     * @return constructed address
+     */
+    public static LegacyZcashAddress fromScriptHash(NetworkParameters params, byte[] hash160) throws AddressFormatException {
+        return new LegacyZcashAddress(params, true, hash160);
+    }
+
+    /**
+     * Construct a {@link LegacyZcashAddress} from its base58 form.
+     * 
+     * @param params
+     *            expected network this address is valid for, or null if if the network should be derived from the
+     *            base58
+     * @param base58
+     *            base58-encoded textual form of the address
+     * @throws AddressFormatException
+     *             if the given base58 doesn't parse or the checksum is invalid
+     * @throws AddressFormatException.WrongNetwork
+     *             if the given address is valid but for a different chain (eg testnet vs mainnet)
+     */
+    public static LegacyZcashAddress fromBase58(@Nullable NetworkParameters params, String base58)
+            throws AddressFormatException, AddressFormatException.WrongNetwork {
+        byte[] versionAndDataBytes = Base58.decodeChecked(base58);
+        int version = versionAndDataBytes[0] & 0xFF;
+        byte[] bytes = Arrays.copyOfRange(versionAndDataBytes, 1, versionAndDataBytes.length);
+        if (params == null) {
+            for (NetworkParameters p : Networks.get()) {
+                if (version == p.getAddressHeader())
+                    return new LegacyZcashAddress(p, false, bytes);
+                else if (version == p.getP2SHHeader())
+                    return new LegacyZcashAddress(p, true, bytes);
+            }
+            throw new AddressFormatException.InvalidPrefix("No network found for " + base58);
+        } else {
+            if (version == params.getAddressHeader())
+                return new LegacyZcashAddress(params, false, bytes);
+            else if (version == params.getP2SHHeader())
+                return new LegacyZcashAddress(params, true, bytes);
+            throw new AddressFormatException.WrongNetwork(version);
+        }
+    }
+
+    /**
+     * Get the version header of an address. This is the first byte of a base58 encoded address.
+     * 
+     * @return version header as one byte
+     */
+    public int getVersion() {
+        return p2sh ? params.getP2SHHeader() : params.getAddressHeader();
+    }
+
+    /**
+     * Returns the base58-encoded textual form, including version and checksum bytes.
+     * 
+     * @return textual form
+     */
+    public String toBase58() {
+        return this.encodeChecked(getVersion(), bytes);
+    }
+
+    /** The (big endian) 20 byte hash that is the core of a Bitcoin address. */
+    @Override
+    public byte[] getHash() {
+        return bytes;
+    }
+
+    /**
+     * Get the type of output script that will be used for sending to the address. This is either
+     * {@link ScriptType#P2PKH} or {@link ScriptType#P2SH}.
+     * 
+     * @return type of output script
+     */
+    @Override
+    public ScriptType getOutputScriptType() {
+        return p2sh ? ScriptType.P2SH : ScriptType.P2PKH;
+    }
+
+    /**
+     * Given an address, examines the version byte and attempts to find a matching NetworkParameters. If you aren't sure
+     * which network the address is intended for (eg, it was provided by a user), you can use this to decide if it is
+     * compatible with the current wallet.
+     * 
+     * @return network the address is valid for
+     * @throws AddressFormatException if the given base58 doesn't parse or the checksum is invalid
+     */
+    public static NetworkParameters getParametersFromAddress(String address) throws AddressFormatException {
+        return LegacyZcashAddress.fromBase58(null, address).getParameters();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        LegacyZcashAddress other = (LegacyZcashAddress) o;
+        return super.equals(other) && this.p2sh == other.p2sh;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(super.hashCode(), p2sh);
+    }
+
+    @Override
+    public String toString() {
+        return toBase58();
+    }
+
+    @Override
+    public LegacyZcashAddress clone() throws CloneNotSupportedException {
+        return (LegacyZcashAddress) super.clone();
+    }
+
+    public static String encodeChecked(int version, byte[] payload) {
+        if (version < 0 || version > 255)
+            throw new IllegalArgumentException("Version not in range.");
+
+        // A stringified buffer is:
+        // 1 byte version + data bytes + 4 bytes check code (a truncated hash)
+        byte[] addressBytes = new byte[2 + payload.length + 4];
+        addressBytes[0] = (byte) P2SH_HEADER_1;
+        addressBytes[1] = (byte) P2SH_HEADER_2;
+        System.arraycopy(payload, 0, addressBytes, 2, payload.length);
+        byte[] checksum = Sha256Hash.hashTwice(addressBytes, 0, payload.length + 2);
+        System.arraycopy(checksum, 0, addressBytes, payload.length + 2, 4);
+        return Base58.encode(addressBytes);
+    }
+
+//    // Comparator for LegacyAddress, left argument must be LegacyAddress, right argument can be any Address
+//    private static final Comparator<Address> LEGACY_ADDRESS_COMPARATOR = Address.PARTIAL_ADDRESS_COMPARATOR
+//            .thenComparingInt(a -> ((LegacyZcashAddress) a).getVersion())                    // Then compare Legacy address version byte
+//            .thenComparing(a -> a.bytes, UnsignedBytes.lexicographicalComparator());    // Then compare Legacy bytes
+//
+//    /**
+//     * {@inheritDoc}
+//     *
+//     * @param o other {@code Address} object
+//     * @return comparison result
+//     */
+//    @Override
+//    public int compareTo(Address o) {
+//       return LEGACY_ADDRESS_COMPARATOR.compare(this, o);
+//    }
+}

src/main/java/org/qortal/crosschain/PirateChain.java

@@ -3,9 +3,7 @@ package org.qortal.crosschain;
 import cash.z.wallet.sdk.rpc.CompactFormats;
 import com.google.common.hash.HashCode;
 import com.rust.litewalletjni.LiteWalletJni;
-import org.bitcoinj.core.Coin;
-import org.bitcoinj.core.Context;
-import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.core.*;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -16,6 +14,7 @@ import org.qortal.api.model.crosschain.PirateChainSendRequest;
 import org.qortal.controller.PirateChainWalletController;
 import org.qortal.crosschain.PirateLightClient.Server;
 import org.qortal.crosschain.PirateLightClient.Server.ConnectionType;
+import org.qortal.crypto.Crypto;
 import org.qortal.settings.Settings;
 import org.qortal.transform.TransformationException;
 import org.qortal.utils.BitTwiddling;
@@ -218,6 +217,14 @@ public class PirateChain extends Bitcoiny {
 		return this.blockchainProvider.getCompactBlocks(startHeight, count);
 	}
 
+
+	/** Returns P2SH address using passed redeem script. */
+	public String deriveP2shAddress(byte[] redeemScriptBytes) {
+		Context.propagate(bitcoinjContext);
+		byte[] redeemScriptHash = Crypto.hash160(redeemScriptBytes);
+		return LegacyZcashAddress.fromScriptHash(this.params, redeemScriptHash).toString();
+	}
+
 	public Long getWalletBalance(String entropy58) throws ForeignBlockchainException {
 		synchronized (this) {
 			PirateChainWalletController walletController = PirateChainWalletController.getInstance();