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/*
* Copyright 2013 Google Inc.
* Copyright 2014-2016 the libsecp256k1 contributors
*
* 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.bitcoin;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.math.BigInteger;
import com.google.common.base.Preconditions;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import static org.bitcoin.NativeSecp256k1Util.*;
/**
* This class holds native methods to handle ECDSA verification.
*
* You can find an example library that can be used for this at https://github.com/bitcoin/secp256k1
*
* To build secp256k1 for use with bitcoinj, run
* `./configure --enable-jni --enable-experimental --enable-module-schnorr --enable-module-ecdh`
* and `make` then copy `.libs/libsecp256k1.so` to your system library path
* or point the JVM to the folder containing it with -Djava.library.path
*
*/
public class NativeSecp256k1 {
private static final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
private static final Lock r = rwl.readLock();
private static final Lock w = rwl.writeLock();
private static ThreadLocal nativeECDSABuffer = new ThreadLocal<>();
/**
* Verifies the given secp256k1 signature in native code. Calling when enabled == false is undefined (probably
* library not loaded)
*
* @param data The data which was signed, must be exactly 32 bytes
* @param signature The signature
* @param pub The public key which did the signing
*/
public static boolean verify(byte[] data, byte[] signature, byte[] pub) throws AssertFailException {
Preconditions.checkArgument(data.length == 32 && signature.length <= 520 && pub.length <= 520);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < 520) {
byteBuff = ByteBuffer.allocateDirect(520);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(data);
byteBuff.put(signature);
byteBuff.put(pub);
r.lock();
try {
return secp256k1_ecdsa_verify(byteBuff, Secp256k1Context.getContext(), signature.length, pub.length) == 1;
} finally {
r.unlock();
}
}
/**
* libsecp256k1 Create an ECDSA signature.
*
* @param data Message hash, 32 bytes
* @param sec Secret key, 32 bytes
* @return sig byte array of signature
*/
public static byte[] sign(byte[] data, byte[] sec) throws AssertFailException {
Preconditions.checkArgument(data.length == 32 && sec.length <= 32);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < 32 + 32) {
byteBuff = ByteBuffer.allocateDirect(32 + 32);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(data);
byteBuff.put(sec);
byte[][] retByteArray;
r.lock();
try {
retByteArray = secp256k1_ecdsa_sign(byteBuff, Secp256k1Context.getContext());
} finally {
r.unlock();
}
byte[] sigArr = retByteArray[0];
int sigLen = new BigInteger(new byte[] { retByteArray[1][0] }).intValue();
int retVal = new BigInteger(new byte[] { retByteArray[1][1] }).intValue();
assertEquals(sigArr.length, sigLen, "Got bad signature length.");
return retVal == 0 ? new byte[0] : sigArr;
}
/**
* libsecp256k1 Seckey Verify - returns 1 if valid, 0 if invalid
*
* @param seckey ECDSA Secret key, 32 bytes
*/
public static boolean secKeyVerify(byte[] seckey) {
Preconditions.checkArgument(seckey.length == 32);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < seckey.length) {
byteBuff = ByteBuffer.allocateDirect(seckey.length);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(seckey);
r.lock();
try {
return secp256k1_ec_seckey_verify(byteBuff, Secp256k1Context.getContext()) == 1;
} finally {
r.unlock();
}
}
/**
* libsecp256k1 Compute Pubkey - computes public key from secret key
*
* @param seckey ECDSA Secret key, 32 bytes
* @return pubkey ECDSA Public key, 33 or 65 bytes
*/
// TODO add a 'compressed' arg
public static byte[] computePubkey(byte[] seckey) throws AssertFailException {
Preconditions.checkArgument(seckey.length == 32);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < seckey.length) {
byteBuff = ByteBuffer.allocateDirect(seckey.length);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(seckey);
byte[][] retByteArray;
r.lock();
try {
retByteArray = secp256k1_ec_pubkey_create(byteBuff, Secp256k1Context.getContext());
} finally {
r.unlock();
}
byte[] pubArr = retByteArray[0];
int pubLen = new BigInteger(new byte[] { retByteArray[1][0] }).intValue();
int retVal = new BigInteger(new byte[] { retByteArray[1][1] }).intValue();
assertEquals(pubArr.length, pubLen, "Got bad pubkey length.");
return retVal == 0 ? new byte[0] : pubArr;
}
/**
* libsecp256k1 Cleanup - This destroys the secp256k1 context object This should be called at the end of the program
* for proper cleanup of the context.
*/
public static synchronized void cleanup() {
w.lock();
try {
secp256k1_destroy_context(Secp256k1Context.getContext());
} finally {
w.unlock();
}
}
public static long cloneContext() {
r.lock();
try {
return secp256k1_ctx_clone(Secp256k1Context.getContext());
} finally {
r.unlock();
}
}
/**
* libsecp256k1 PrivKey Tweak-Mul - Tweak privkey by multiplying to it
*
* @param tweak some bytes to tweak with
* @param privkey 32-byte seckey
*/
public static byte[] privKeyTweakMul(byte[] privkey, byte[] tweak) throws AssertFailException {
Preconditions.checkArgument(privkey.length == 32);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < privkey.length + tweak.length) {
byteBuff = ByteBuffer.allocateDirect(privkey.length + tweak.length);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(privkey);
byteBuff.put(tweak);
byte[][] retByteArray;
r.lock();
try {
retByteArray = secp256k1_privkey_tweak_mul(byteBuff, Secp256k1Context.getContext());
} finally {
r.unlock();
}
byte[] privArr = retByteArray[0];
int privLen = (byte) new BigInteger(new byte[] { retByteArray[1][0] }).intValue() & 0xFF;
int retVal = new BigInteger(new byte[] { retByteArray[1][1] }).intValue();
assertEquals(privArr.length, privLen, "Got bad pubkey length.");
assertEquals(retVal, 1, "Failed return value check.");
return privArr;
}
/**
* libsecp256k1 PrivKey Tweak-Add - Tweak privkey by adding to it
*
* @param tweak some bytes to tweak with
* @param privkey 32-byte seckey
*/
public static byte[] privKeyTweakAdd(byte[] privkey, byte[] tweak) throws AssertFailException {
Preconditions.checkArgument(privkey.length == 32);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < privkey.length + tweak.length) {
byteBuff = ByteBuffer.allocateDirect(privkey.length + tweak.length);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(privkey);
byteBuff.put(tweak);
byte[][] retByteArray;
r.lock();
try {
retByteArray = secp256k1_privkey_tweak_add(byteBuff, Secp256k1Context.getContext());
} finally {
r.unlock();
}
byte[] privArr = retByteArray[0];
int privLen = (byte) new BigInteger(new byte[] { retByteArray[1][0] }).intValue() & 0xFF;
int retVal = new BigInteger(new byte[] { retByteArray[1][1] }).intValue();
assertEquals(privArr.length, privLen, "Got bad pubkey length.");
assertEquals(retVal, 1, "Failed return value check.");
return privArr;
}
/**
* libsecp256k1 PubKey Tweak-Add - Tweak pubkey by adding to it
*
* @param tweak some bytes to tweak with
* @param pubkey 32-byte seckey
*/
public static byte[] pubKeyTweakAdd(byte[] pubkey, byte[] tweak) throws AssertFailException {
Preconditions.checkArgument(pubkey.length == 33 || pubkey.length == 65);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < pubkey.length + tweak.length) {
byteBuff = ByteBuffer.allocateDirect(pubkey.length + tweak.length);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(pubkey);
byteBuff.put(tweak);
byte[][] retByteArray;
r.lock();
try {
retByteArray = secp256k1_pubkey_tweak_add(byteBuff, Secp256k1Context.getContext(), pubkey.length);
} finally {
r.unlock();
}
byte[] pubArr = retByteArray[0];
int pubLen = (byte) new BigInteger(new byte[] { retByteArray[1][0] }).intValue() & 0xFF;
int retVal = new BigInteger(new byte[] { retByteArray[1][1] }).intValue();
assertEquals(pubArr.length, pubLen, "Got bad pubkey length.");
assertEquals(retVal, 1, "Failed return value check.");
return pubArr;
}
/**
* libsecp256k1 PubKey Tweak-Mul - Tweak pubkey by multiplying to it
*
* @param tweak some bytes to tweak with
* @param pubkey 32-byte seckey
*/
public static byte[] pubKeyTweakMul(byte[] pubkey, byte[] tweak) throws AssertFailException {
Preconditions.checkArgument(pubkey.length == 33 || pubkey.length == 65);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < pubkey.length + tweak.length) {
byteBuff = ByteBuffer.allocateDirect(pubkey.length + tweak.length);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(pubkey);
byteBuff.put(tweak);
byte[][] retByteArray;
r.lock();
try {
retByteArray = secp256k1_pubkey_tweak_mul(byteBuff, Secp256k1Context.getContext(), pubkey.length);
} finally {
r.unlock();
}
byte[] pubArr = retByteArray[0];
int pubLen = (byte) new BigInteger(new byte[] { retByteArray[1][0] }).intValue() & 0xFF;
int retVal = new BigInteger(new byte[] { retByteArray[1][1] }).intValue();
assertEquals(pubArr.length, pubLen, "Got bad pubkey length.");
assertEquals(retVal, 1, "Failed return value check.");
return pubArr;
}
/**
* libsecp256k1 create ECDH secret - constant time ECDH calculation
*
* @param seckey byte array of secret key used in exponentiaion
* @param pubkey byte array of public key used in exponentiaion
*/
public static byte[] createECDHSecret(byte[] seckey, byte[] pubkey) throws AssertFailException {
Preconditions.checkArgument(seckey.length <= 32 && pubkey.length <= 65);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < 32 + pubkey.length) {
byteBuff = ByteBuffer.allocateDirect(32 + pubkey.length);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(seckey);
byteBuff.put(pubkey);
byte[][] retByteArray;
r.lock();
try {
retByteArray = secp256k1_ecdh(byteBuff, Secp256k1Context.getContext(), pubkey.length);
} finally {
r.unlock();
}
byte[] resArr = retByteArray[0];
int retVal = new BigInteger(new byte[] { retByteArray[1][0] }).intValue();
assertEquals(resArr.length, 32, "Got bad result length.");
assertEquals(retVal, 1, "Failed return value check.");
return resArr;
}
/**
* libsecp256k1 randomize - updates the context randomization
*
* @param seed 32-byte random seed
*/
public static synchronized boolean randomize(byte[] seed) throws AssertFailException {
Preconditions.checkArgument(seed.length == 32 || seed == null);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null || byteBuff.capacity() < seed.length) {
byteBuff = ByteBuffer.allocateDirect(seed.length);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(seed);
w.lock();
try {
return secp256k1_context_randomize(byteBuff, Secp256k1Context.getContext()) == 1;
} finally {
w.unlock();
}
}
public static byte[] schnorrSign(byte[] data, byte[] sec) throws AssertFailException {
Preconditions.checkArgument(data.length == 32 && sec.length <= 32);
ByteBuffer byteBuff = nativeECDSABuffer.get();
if (byteBuff == null) {
byteBuff = ByteBuffer.allocateDirect(32 + 32);
byteBuff.order(ByteOrder.nativeOrder());
nativeECDSABuffer.set(byteBuff);
}
byteBuff.rewind();
byteBuff.put(data);
byteBuff.put(sec);
byte[][] retByteArray;
r.lock();
try {
retByteArray = secp256k1_schnorr_sign(byteBuff, Secp256k1Context.getContext());
} finally {
r.unlock();
}
byte[] sigArr = retByteArray[0];
int retVal = new BigInteger(new byte[] { retByteArray[1][0] }).intValue();
assertEquals(sigArr.length, 64, "Got bad signature length.");
return retVal == 0 ? new byte[0] : sigArr;
}
private static native long secp256k1_ctx_clone(long context);
private static native int secp256k1_context_randomize(ByteBuffer byteBuff, long context);
private static native byte[][] secp256k1_privkey_tweak_add(ByteBuffer byteBuff, long context);
private static native byte[][] secp256k1_privkey_tweak_mul(ByteBuffer byteBuff, long context);
private static native byte[][] secp256k1_pubkey_tweak_add(ByteBuffer byteBuff, long context, int pubLen);
private static native byte[][] secp256k1_pubkey_tweak_mul(ByteBuffer byteBuff, long context, int pubLen);
private static native void secp256k1_destroy_context(long context);
private static native int secp256k1_ecdsa_verify(ByteBuffer byteBuff, long context, int sigLen, int pubLen);
private static native byte[][] secp256k1_ecdsa_sign(ByteBuffer byteBuff, long context);
private static native int secp256k1_ec_seckey_verify(ByteBuffer byteBuff, long context);
private static native byte[][] secp256k1_ec_pubkey_create(ByteBuffer byteBuff, long context);
private static native byte[][] secp256k1_ec_pubkey_parse(ByteBuffer byteBuff, long context, int inputLen);
private static native byte[][] secp256k1_schnorr_sign(ByteBuffer byteBuff, long context);
private static native byte[][] secp256k1_ecdh(ByteBuffer byteBuff, long context, int inputLen);
}
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