org.bitcoinj.script.ScriptPattern Maven / Gradle / Ivy
/*
* Copyright 2017 John L. Jegutanis
* Copyright 2018 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.
*/
package org.bitcoinj.script;
import org.bitcoinj.core.Address;
import org.bitcoinj.core.Sha256Hash;
import org.bitcoinj.core.Utils;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.List;
import static org.bitcoinj.script.Script.decodeFromOpN;
import static org.bitcoinj.script.ScriptOpCodes.*;
/**
* This is a Script pattern matcher with some typical script patterns
*/
public class ScriptPattern {
/**
* Returns true if this script is of the form {@code DUP HASH160 EQUALVERIFY CHECKSIG}, ie, payment to an
* address like {@code 1VayNert3x1KzbpzMGt2qdqrAThiRovi8}. This form was originally intended for the case where you wish
* to send somebody money with a written code because their node is offline, but over time has become the standard
* way to make payments due to the short and recognizable base58 form addresses come in.
*/
public static boolean isP2PKH(Script script) {
List chunks = script.chunks;
if (chunks.size() != 5)
return false;
if (!chunks.get(0).equalsOpCode(OP_DUP))
return false;
if (!chunks.get(1).equalsOpCode(OP_HASH160))
return false;
byte[] chunk2data = chunks.get(2).data;
if (chunk2data == null)
return false;
if (chunk2data.length != Address.LENGTH)
return false;
if (!chunks.get(3).equalsOpCode(OP_EQUALVERIFY))
return false;
if (!chunks.get(4).equalsOpCode(OP_CHECKSIG))
return false;
return true;
}
/**
* Extract the pubkey hash from a P2PKH scriptPubKey. It's important that the script is in the correct form, so you
* will want to guard calls to this method with {@link #isP2PKH(Script)}.
*/
public static byte[] extractHashFromP2PKH(Script script) {
return script.chunks.get(2).data;
}
/**
*
* Whether or not this is a scriptPubKey representing a P2SH output. In such outputs, the logic that
* controls reclamation is not actually in the output at all. Instead there's just a hash, and it's up to the
* spending input to provide a program matching that hash.
*
*
* P2SH is described by BIP16.
*
*/
public static boolean isP2SH(Script script) {
List chunks = script.chunks;
// We check for the effective serialized form because BIP16 defines a P2SH output using an exact byte
// template, not the logical program structure. Thus you can have two programs that look identical when
// printed out but one is a P2SH script and the other isn't! :(
// We explicitly test that the op code used to load the 20 bytes is 0x14 and not something logically
// equivalent like {@code OP_HASH160 OP_PUSHDATA1 0x14 <20 bytes of script hash> OP_EQUAL}
if (chunks.size() != 3)
return false;
if (!chunks.get(0).equalsOpCode(OP_HASH160))
return false;
ScriptChunk chunk1 = chunks.get(1);
if (chunk1.opcode != 0x14)
return false;
byte[] chunk1data = chunk1.data;
if (chunk1data == null)
return false;
if (chunk1data.length != Address.LENGTH)
return false;
if (!chunks.get(2).equalsOpCode(OP_EQUAL))
return false;
return true;
}
/**
* Extract the script hash from a P2SH scriptPubKey. It's important that the script is in the correct form, so you
* will want to guard calls to this method with {@link #isP2SH(Script)}.
*/
public static byte[] extractHashFromP2SH(Script script) {
return script.chunks.get(1).data;
}
/**
* Returns true if this script is of the form {@code OP_CHECKSIG}. This form was originally intended for transactions
* where the peers talked to each other directly via TCP/IP, but has fallen out of favor with time due to that mode
* of operation being susceptible to man-in-the-middle attacks. It is still used in coinbase outputs and can be
* useful more exotic types of transaction, but today most payments are to addresses.
*/
public static boolean isP2PK(Script script) {
List chunks = script.chunks;
if (chunks.size() != 2)
return false;
ScriptChunk chunk0 = chunks.get(0);
if (chunk0.isOpCode())
return false;
byte[] chunk0data = chunk0.data;
if (chunk0data == null)
return false;
if (chunk0data.length <= 1)
return false;
if (!chunks.get(1).equalsOpCode(OP_CHECKSIG))
return false;
return true;
}
/**
* Extract the pubkey from a P2SH scriptPubKey. It's important that the script is in the correct form, so you will
* want to guard calls to this method with {@link #isP2PK(Script)}.
*/
public static byte[] extractKeyFromP2PK(Script script) {
return script.chunks.get(0).data;
}
/**
* Returns whether this script matches the format used for m-of-n multisig outputs:
* {@code [m] [keys...] [n] CHECKMULTISIG}
*/
public static boolean isSentToMultisig(Script script) {
List chunks = script.chunks;
if (chunks.size() < 4) return false;
ScriptChunk chunk = chunks.get(chunks.size() - 1);
// Must end in OP_CHECKMULTISIG[VERIFY].
if (!chunk.isOpCode()) return false;
if (!(chunk.equalsOpCode(OP_CHECKMULTISIG) || chunk.equalsOpCode(OP_CHECKMULTISIGVERIFY))) return false;
try {
// Second to last chunk must be an OP_N opcode and there should be that many data chunks (keys).
ScriptChunk m = chunks.get(chunks.size() - 2);
if (!m.isOpCode()) return false;
int numKeys = decodeFromOpN(m.opcode);
if (numKeys < 1 || chunks.size() != 3 + numKeys) return false;
for (int i = 1; i < chunks.size() - 2; i++) {
if (chunks.get(i).isOpCode()) return false;
}
// First chunk must be an OP_N opcode too.
if (decodeFromOpN(chunks.get(0).opcode) < 1) return false;
} catch (IllegalStateException e) {
return false; // Not an OP_N opcode.
}
return true;
}
/**
* Returns whether this script matches the format used for LOCKTIMEVERIFY transactions.
*/
public static boolean isSentToCltvPaymentChannel(Script script) {
List chunks = script.chunks;
if (chunks.size() != 10) return false;
// Check that opcodes match the pre-determined format.
if (!chunks.get(0).equalsOpCode(OP_IF)) return false;
// chunk[1] = recipient pubkey
if (!chunks.get(2).equalsOpCode(OP_CHECKSIGVERIFY)) return false;
if (!chunks.get(3).equalsOpCode(OP_ELSE)) return false;
// chunk[4] = locktime
if (!chunks.get(5).equalsOpCode(OP_CHECKLOCKTIMEVERIFY)) return false;
if (!chunks.get(6).equalsOpCode(OP_DROP)) return false;
if (!chunks.get(7).equalsOpCode(OP_ENDIF)) return false;
// chunk[8] = sender pubkey
if (!chunks.get(9).equalsOpCode(OP_CHECKSIG)) return false;
return true;
}
/**
* Retrieves the public key of the sender from a LOCKTIMEVERIFY transaction. It's important that the script is in
* the correct form, so you will want to guard calls to this method with
* {@link #isSentToCltvPaymentChannel(Script)}.
*/
public static byte[] extractSenderPubKeyFromCltvPaymentChannel(Script script) {
return script.chunks.get(8).data;
}
/**
* Retrieves the public key of the recipient from a LOCKTIMEVERIFY transaction. It's important that the script is in
* the correct form, so you will want to guard calls to this method with
* {@link #isSentToCltvPaymentChannel(Script)}.
*/
public static byte[] extractRecipientPubKeyFromCltvPaymentChannel(Script script) {
return script.chunks.get(1).data;
}
/**
* Retrieves the locktime from a LOCKTIMEVERIFY transaction. It's important that the script is in the correct form,
* so you will want to guard calls to this method with {@link #isSentToCltvPaymentChannel(Script)}.
*/
public static BigInteger extractExpiryFromCltvPaymentChannel(Script script) {
return Script.castToBigInteger(script.chunks.get(4).data, 5, false);
}
/**
* Returns whether this script is using OP_RETURN to store arbitrary data.
*/
public static boolean isOpReturn(Script script) {
List chunks = script.chunks;
return chunks.size() > 0 && chunks.get(0).equalsOpCode(ScriptOpCodes.OP_RETURN);
}
}