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/*-
*
* Hedera Java SDK
*
* Copyright (C) 2020 - 2022 Hedera Hashgraph, LLC
*
* 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 com.hedera.hashgraph.sdk;
import com.google.common.base.Joiner;
import com.google.errorprone.annotations.Var;
import com.hedera.hashgraph.sdk.utils.Bip32Utils;
import org.bouncycastle.crypto.digests.SHA256Digest;
import org.bouncycastle.crypto.digests.SHA512Digest;
import org.bouncycastle.crypto.generators.PKCS5S2ParametersGenerator;
import org.bouncycastle.crypto.params.KeyParameter;
import javax.annotation.Nullable;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.ref.SoftReference;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.nio.IntBuffer;
import java.text.Normalizer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.function.Consumer;
import java.util.function.Supplier;
import static java.nio.charset.StandardCharsets.UTF_8;
/**
* BIP-39 24-word mnemonic phrases compatible with the Android and iOS mobile wallets.
*/
public final class Mnemonic {
// by storing our word list in a SoftReference, the GC is free to evict it at its discretion
// but the implementation is meant to wait until free space is needed
@Nullable
private static SoftReference> bip39WordList = null;
@Nullable
private static SoftReference> legacyWordList = null;
/**
* The list of words in this mnemonic.
*/
public final List words;
@Nullable
private String asString;
@SuppressWarnings("StaticAssignmentInConstructor")
private Mnemonic(List words) {
this.words = Collections.unmodifiableList(words);
}
/**
* Construct a mnemonic from a 24-word list. {@link Mnemonic#validate()}
* is called before returning, and it will throw an exception if it
* does not pass validation. An invalid mnemonic can still create valid
* Ed25519 private keys, so the exception will contain the mnemonic in case
* the user wants to ignore the outcome of the validation.
*
* @param words the 24-word list that constitutes a mnemonic phrase.
* @return {@code this}
* @throws BadMnemonicException if the mnemonic does not pass validation.
* @see #validate() the function that validates the mnemonic.
*/
public static Mnemonic fromWords(List words) throws BadMnemonicException {
Mnemonic mnemonic = new Mnemonic(words);
if (words.size() != 22) {
mnemonic.validate();
}
return mnemonic;
}
/**
* Recover a mnemonic from a string, splitting on spaces.
*
* @param mnemonicString The string to recover the mnemonic from
* @return {@code this}
* @throws BadMnemonicException if the mnemonic does not pass validation.
*/
public static Mnemonic fromString(String mnemonicString) throws BadMnemonicException {
String toLowerCase = mnemonicString.toLowerCase();
return Mnemonic.fromWords(Arrays.asList(toLowerCase.split(" ")));
}
/**
* Returns a new random 24-word mnemonic from the BIP-39 standard English word list.
*
* @return {@code this}
*/
public static Mnemonic generate24() {
var entropy = new byte[32];
ThreadLocalSecureRandom.current().nextBytes(entropy);
return new Mnemonic(entropyToWords(entropy));
}
/**
* Returns a new random 12-word mnemonic from the BIP-39 standard English word list.
*
* @return {@code this}
*/
public static Mnemonic generate12() {
var entropy = new byte[16];
ThreadLocalSecureRandom.current().nextBytes(entropy);
return new Mnemonic(entropyToWords(entropy));
}
private static List entropyToWords(byte[] entropy) {
if (entropy.length != 16 && entropy.length != 32) {
throw new IllegalArgumentException("invalid entropy byte length: " + entropy.length);
}
// checksum for 256 bits is one byte
List wordList;
ArrayList words;
byte[] bytes;
if (entropy.length == 16) {
wordList = getWordList(false);
bytes = Arrays.copyOf(entropy, 17);
bytes[16] = (byte) (checksum(entropy) & 0xF0);
words = new ArrayList<>(12);
} else {
wordList = getWordList(false);
bytes = Arrays.copyOf(entropy, 33);
bytes[32] = checksum(entropy);
words = new ArrayList<>(24);
}
@Var var scratch = 0;
@Var var offset = 0;
for (var b : bytes) {
// shift `bytes` into `scratch`, popping off 11-bit indices when we can
scratch <<= 8;
// bitwise operations implicitly widen to `int` so mask off sign-extended bits
scratch |= b & 0xFF;
offset += 8;
if (offset >= 11) {
// pop 11 bits off the end of `scratch` and into `index`
var index = (scratch >> (offset - 11)) & 0x7FF;
offset -= 11;
words.add(wordList.get(index));
}
}
return words;
}
// hash the first 32 bytes of `entropy` and return the first byte of the digest
private static byte checksum(byte[] entropy) {
SHA256Digest digest = new SHA256Digest();
// hash the first
if (entropy.length == 17 || entropy.length == 16) {
digest.update(entropy, 0, 16);
} else {
digest.update(entropy, 0, 32);
}
byte[] checksum = new byte[digest.getDigestSize()];
digest.doFinal(checksum, 0);
return checksum[0];
}
private static int getWordIndex(CharSequence word, boolean isLegacy) {
var wordList = getWordList(isLegacy);
@Var
var found = -1;
for (var i = 0; i < wordList.size(); i++) {
if (word.toString().equals(wordList.get(i))) {
found = i;
}
}
return found;
}
private static List getWordList(boolean isLegacy) {
if (isLegacy) {
return getSpecificWordList(
() -> legacyWordList,
() -> readWordList(true),
(newWordList) -> legacyWordList = newWordList
);
} else {
return getSpecificWordList(
() -> bip39WordList,
() -> readWordList(false),
(newWordList) -> bip39WordList = newWordList
);
}
}
private static synchronized List getSpecificWordList(
Supplier>> getCurrentWordList,
Supplier> getNewWordList,
Consumer>> setCurrentWordList
) {
var localWordList = getCurrentWordList.get();
if (localWordList == null || localWordList.get() == null) {
List words = getNewWordList.get();
setCurrentWordList.accept(new SoftReference<>(words));
// immediately return the strong reference
return words;
}
return localWordList.get();
}
private static List readWordList(boolean isLegacy) {
if (isLegacy) {
InputStream wordStream = Mnemonic.class.getClassLoader().getResourceAsStream("legacy-english.txt");
try (BufferedReader reader = new BufferedReader(new InputStreamReader(Objects.requireNonNull(wordStream), UTF_8))) {
ArrayList words = new ArrayList<>(4096);
for (String word = reader.readLine(); word != null; word = reader.readLine()) {
words.add(word);
}
return Collections.unmodifiableList(words);
} catch (IOException e) {
throw new RuntimeException(e);
}
} else {
InputStream wordStream = Mnemonic.class.getClassLoader().getResourceAsStream("bip39-english.txt");
try (BufferedReader reader = new BufferedReader(new InputStreamReader(Objects.requireNonNull(wordStream), UTF_8))) {
ArrayList words = new ArrayList<>(2048);
for (String word = reader.readLine(); word != null; word = reader.readLine()) {
words.add(word);
}
return Collections.unmodifiableList(words);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
private static int[] convertRadix(int[] nums, int fromRadix, int toRadix, int toLength) {
@Var BigInteger num = BigInteger.valueOf(0);
for (int element : nums) {
num = num.multiply(BigInteger.valueOf(fromRadix));
num = num.add(BigInteger.valueOf(element));
}
var result = new int[toLength];
for (@Var var i = toLength - 1; i >= 0; i -= 1) {
BigInteger tem = num.divide(BigInteger.valueOf(toRadix));
BigInteger rem = num.mod(BigInteger.valueOf(toRadix));
num = tem;
result[i] = rem.intValue();
}
return result;
}
private static int crc8(int[] data) {
@Var var crc = 0xFF;
for (var i = 0; i < data.length - 1; i += 1) {
crc ^= data[i];
for (var j = 0; j < 8; j += 1) {
crc = (crc >>> 1) ^ (((crc & 1) == 0) ? 0 : 0xB2);
}
}
return crc ^ 0xFF;
}
private static boolean[] bytesToBits(byte[] dat) {
var bits = new boolean[dat.length * 8];
Arrays.fill(bits, Boolean.FALSE);
for (int i = 0; i < dat.length; i++) {
for (int j = 0; j < 8; j++) {
bits[(i * 8) + j] = (dat[i] & (1 << (7 - j))) != 0;
}
}
return bits;
}
/**
* @deprecated use {@link #toStandardEd25519PrivateKey(String, int)} ()} or {@link #toStandardECDSAsecp256k1PrivateKey(String, int)} (String, int)} instead
* Recover a private key from this mnemonic phrase.
*
* This is not compatible with the phrases generated by the Android and iOS wallets;
* use the no-passphrase version instead.
*
* @param passphrase the passphrase used to protect the mnemonic
* @return the recovered key; use {@link PrivateKey#derive(int)} to get a
* key for an account index (0 for default account)
* @see PrivateKey#fromMnemonic(Mnemonic, String)
*/
@Deprecated
public PrivateKey toPrivateKey(String passphrase) {
return PrivateKey.fromMnemonic(this, passphrase);
}
/**
* Extract the private key.
*
* @return the private key
* @throws BadMnemonicException when there are issues with the mnemonic
*/
public PrivateKey toLegacyPrivateKey() throws BadMnemonicException {
if (this.words.size() == 22) {
return PrivateKey.fromBytes(this.wordsToLegacyEntropy());
}
return PrivateKey.fromBytes(this.wordsToLegacyEntropy2());
}
/**
* @deprecated use {@link #toStandardEd25519PrivateKey(String, int)} ()} or {@link #toStandardECDSAsecp256k1PrivateKey(String, int)} (String, int)} instead
* Recover a private key from this mnemonic phrase.
*
* @return the recovered key; use
* {@link PrivateKey#derive(int)} to get
* a key for an account index (0 for
* default account)
* @see PrivateKey#fromMnemonic(Mnemonic)
*/
@Deprecated
public PrivateKey toPrivateKey() {
return toPrivateKey("");
}
private void validate() throws BadMnemonicException {
if (words.size() != 24 && words.size() != 12) {
throw new BadMnemonicException(this, BadMnemonicReason.BadLength);
}
ArrayList unknownIndices = new ArrayList<>();
for (int i = 0; i < words.size(); i++) {
if (getWordIndex(words.get(i), false) < 0) {
unknownIndices.add(i);
}
}
if (!unknownIndices.isEmpty()) {
throw new BadMnemonicException(this, BadMnemonicReason.UnknownWords, unknownIndices);
}
if (words.size() != 22) {
// test the checksum encoded in the mnemonic
byte[] entropyAndChecksum = wordsToEntropyAndChecksum();
// ignores the 33rd byte
byte expectedChecksum;
byte givenChecksum;
if (words.size() == 12) {
expectedChecksum = (byte) (checksum(entropyAndChecksum) & 0xF0);
givenChecksum = entropyAndChecksum[16];
} else {
expectedChecksum = checksum(entropyAndChecksum);
givenChecksum = entropyAndChecksum[32];
}
if (givenChecksum != expectedChecksum) {
throw new BadMnemonicException(this, BadMnemonicReason.ChecksumMismatch);
}
}
}
@Override
public String toString() {
if (asString == null) {
asString = Joiner.on(' ').join(words);
}
return asString;
}
/**
* Convert passphrase to a byte array.
*
* @param passphrase the passphrase
* @return the byte array
*/
byte[] toSeed(String passphrase) {
String salt = Normalizer.normalize("mnemonic" + passphrase, Normalizer.Form.NFKD);
// BIP-39 seed generation
PKCS5S2ParametersGenerator pbkdf2 = new PKCS5S2ParametersGenerator(new SHA512Digest());
pbkdf2.init(
toString().getBytes(UTF_8),
salt.getBytes(UTF_8),
2048);
KeyParameter key = (KeyParameter) pbkdf2.generateDerivedParameters(512);
return key.getKey();
}
private byte[] wordsToEntropyAndChecksum() {
if (words.size() != 24 && words.size() != 12) {
// should be checked in `validate()`
throw new IllegalStateException(
"(BUG) expected 24-word mnemonic, got " + words.size() + " words");
}
ByteBuffer buffer;
if (words.size() == 12) {
buffer = ByteBuffer.allocate(17);
} else {
buffer = ByteBuffer.allocate(33);
}
// reverse algorithm of `entropyToWords()` below
@Var int scratch = 0;
@Var int offset = 0;
for (CharSequence word : words) {
int index = getWordIndex(word, false);
if (index < 0) {
// should also be checked in `validate()`
throw new IllegalStateException("(BUG) word not in word list: " + word);
} else if (index > 0x7FF) {
throw new IndexOutOfBoundsException("(BUG) index out of bounds: " + index);
}
scratch <<= 11;
scratch |= index;
offset += 11;
while (offset >= 8) {
// truncation is what we want here
buffer.put((byte) (scratch >> (offset - 8)));
offset -= 8;
}
}
if (offset != 0) {
buffer.put((byte) (scratch << offset));
}
return buffer.array();
}
private byte[] wordsToLegacyEntropy() throws BadMnemonicException {
var indices = new int[words.size()];
for (var i = 0; i < words.size(); i++) {
indices[i] = getWordIndex(words.get(i), true);
}
var data = convertRadix(indices, 4096, 256, 33);
var crc = data[data.length - 1];
var result = new int[data.length - 1];
for (var i = 0; i < data.length - 1; i += 1) {
result[i] = data[i] ^ crc;
}
//int to byte conversion
ByteBuffer byteBuffer = ByteBuffer.allocate(result.length * 4);
IntBuffer intBuffer = byteBuffer.asIntBuffer();
intBuffer.put(result);
var crc2 = crc8(result);
if (crc != crc2) {
throw new BadMnemonicException(this, BadMnemonicReason.ChecksumMismatch);
}
byte[] array = byteBuffer.array();
@Var var i = 0;
@Var var j = 3;
byte[] array2 = new byte[data.length - 1];
//remove all the fill 0s
while (j < array.length) {
array2[i] = array[j];
i++;
j = j + 4;
}
return array2;
}
private byte[] wordsToLegacyEntropy2() throws BadMnemonicException {
var concatBitsLen = this.words.size() * 11;
var concatBits = new boolean[concatBitsLen];
Arrays.fill(concatBits, Boolean.FALSE);
for (int index = 0; index < this.words.size(); index++) {
var nds = Collections.binarySearch(getWordList(false), this.words.get(index), null);
for (int i = 0; i < 11; i++) {
concatBits[(index * 11) + i] = (nds & (1 << (10 - i))) != 0;
}
}
var checksumBitsLen = concatBitsLen / 33;
var entropyBitsLen = concatBitsLen - checksumBitsLen;
var entropy = new byte[entropyBitsLen / 8];
for (int i = 0; i < entropy.length; i++) {
for (int j = 0; j < 8; j++) {
if (concatBits[(i * 8) + j]) {
entropy[i] |= (byte) (1 << (7 - j));
}
}
}
var digest = new SHA256Digest();
byte[] hash = new byte[entropy.length];
digest.update(entropy, 0, entropy.length);
digest.doFinal(hash, 0);
var hashBits = bytesToBits(hash);
for (int i = 0; i < checksumBitsLen; i++) {
if (concatBits[entropyBitsLen + i] != hashBits[i]) {
throw new BadMnemonicException(this, BadMnemonicReason.ChecksumMismatch);
}
}
return entropy;
}
/**
* Recover an Ed25519 private key from this mnemonic phrase, with an
* optional passphrase.
*
* @param passphrase the passphrase used to protect the mnemonic
* @param index the derivation index
* @return the private key
*/
public PrivateKey toStandardEd25519PrivateKey(String passphrase, int index) {
var seed = this.toSeed(passphrase);
PrivateKey derivedKey = PrivateKey.fromSeedED25519(seed);
for (int i : new int[]{44, 3030, 0, 0, index}) {
derivedKey = derivedKey.derive(i);
}
return derivedKey;
}
/**
* Recover an ECDSAsecp256k1 private key from this mnemonic phrase, with an
* optional passphrase.
*
* @param passphrase the passphrase used to protect the mnemonic
* @param index the derivation index
* @return the private key
*/
public PrivateKey toStandardECDSAsecp256k1PrivateKey(String passphrase, int index) {
var seed = this.toSeed(passphrase);
PrivateKey derivedKey = PrivateKey.fromSeedECDSAsecp256k1(seed);
// Harden the first 3 indexes
for (int i : new int[]{
Bip32Utils.toHardenedIndex(44),
Bip32Utils.toHardenedIndex(3030),
Bip32Utils.toHardenedIndex(0),
0,
index}) {
derivedKey = derivedKey.derive(i);
}
return derivedKey;
}
}