环境
依赖环境还是BIP全家桶
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implementation 'io.github.novacrypto:BIP44:0.0.3' // implementation 'io.github.novacrypto:BIP32:0.0.9' //存在少许问题 implementation 'com.lhalcyon:bip32:1.0.0' // 上面的BIP32有少许问题,笔者做了一些修改,已经上传lib implementation 'io.github.novacrypto:BIP39:0.1.9' |
助记词解锁钱包
校验助记词
对用户输入的助记词需要进行校验
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// validate mnemonic try { MnemonicValidator.ofWordList(English.INSTANCE).validate(mnemonics); } catch (InvalidChecksumException e) { e.printStackTrace(); } catch (InvalidWordCountException e) { e.printStackTrace(); } catch (WordNotFoundException e) { e.printStackTrace(); } catch (UnexpectedWhiteSpaceException e) { e.printStackTrace(); } |
解锁钱包
助记词解锁其实与创建钱包过程一致,只是增加了校验重复钱包的逻辑
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public Flowable<HLWallet> importMnemonic(Context context, String password, String mnemonics) { Flowable<String> flowable = Flowable.just(mnemonics); return flowable .flatMap(s -> { ECKeyPair keyPair = generateKeyPair(s); WalletFile walletFile = Wallet.createLight(password, keyPair); HLWallet hlWallet = new HLWallet(walletFile); if (WalletManager.shared().isWalletExist(hlWallet.getAddress())) { return Flowable.error(new HLError(ReplyCode.walletExisted, new Throwable("Wallet existed!"))); } WalletManager.shared().saveWallet(context, hlWallet); return Flowable.just(hlWallet); }); } |
私钥解锁钱包
私钥解锁/导入钱包的过程也与创建时大体一致
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public Flowable<HLWallet> importPrivateKey(Context context, String privateKey, String password) { if (privateKey.startsWith(Constant.PREFIX_16)) { privateKey = privateKey.substring(Constant.PREFIX_16.length()); } Flowable<String> flowable = Flowable.just(privateKey); return flowable.flatMap(s -> { byte[] privateBytes = Hex.decode(s); ECKeyPair ecKeyPair = ECKeyPair.create(privateBytes); WalletFile walletFile = Wallet.createLight(password, ecKeyPair); HLWallet hlWallet = new HLWallet(walletFile); if (WalletManager.shared().isWalletExist(hlWallet.getAddress())) { return Flowable.error(new HLError(ReplyCode.walletExisted, new Throwable("Wallet existed!"))); } WalletManager.shared().saveWallet(context, hlWallet); return Flowable.just(hlWallet); }); } |
Keystore解锁钱包
Keystore解锁钱包需要重点来讲
直接先上代码
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public Flowable<HLWallet> importKeystoreViaWeb3j(Context context, String keystore, String password) { return Flowable.just(keystore) .flatMap(s -> { ObjectMapper objectMapper = new ObjectMapper(); WalletFile walletFile = objectMapper.readValue(keystore, WalletFile.class); ECKeyPair keyPair = Wallet.decrypt(password, walletFile); HLWallet hlWallet = new HLWallet(walletFile); WalletFile generateWalletFile = Wallet.createLight(password, keyPair); if (!generateWalletFile.getAddress().equalsIgnoreCase(walletFile.getAddress())) { return Flowable.error(new HLError(ReplyCode.failure, new Throwable("address doesn't match private key"))); } if (WalletManager.shared().isWalletExist(hlWallet.getAddress())) { return Flowable.error(new HLError(ReplyCode.walletExisted, new Throwable("Wallet existed!"))); } WalletManager.shared().saveWallet(context, hlWallet); return Flowable.just(hlWallet); }); } |
其过程主要是通过 WalletFile / Keystore + Password
得到 EcKeyPair
接着得到其他信息,主要API为
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ECKeyPair keyPair = Wallet.decrypt(password, walletFile); |
增加了校验钱包是否已存在,以及Keystore是否与私钥匹配的逻辑
看似过程那么完美,其实当真正运用中就会发现程序走到这里经常OOM!
报错信息截取如下:
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at org.spongycastle.crypto.generators.SCrypt.SMix(SCrypt.java:143) at org.spongycastle.crypto.generators.SCrypt.MFcrypt(SCrypt.java:87) at org.spongycastle.crypto.generators.SCrypt.generate(SCrypt.java:66) at org.web3j.crypto.Wallet.generateDerivedScryptKey(Wallet.java:136) at org.web3j.crypto.Wallet.decrypt(Wallet.java:214) |
进一步调试发现,是因为当N
过大时,
org.spongycastle.crypto.generators.SCrypt.SMix(..)
方法里的 124 行左右
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for (int i = 0; i < N; ++i) { V[i] = Arrays.clone(X); ... } |
这里不停地clone,导致了内存溢出Crash . 说到这里,不得不说一下创建钱包时,我们的选择
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Wallet.createLight(password, keyPair) |
这里使用的是创建轻量级钱包,其原始调用为
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public static WalletFile create(String password, ECKeyPair ecKeyPair, int n, int p) |
这里的N
,P
是可以自定义赋值的,其意义可自行google下.简单地来说,N
越大,钱包加密程度越高.
当我们创建钱包是调用的createLight(...)
, 而从 imToken 创建的钱包是采用的自定义大于我们’轻量’的标准的,因此从 imToken中创建的钱包导出Keystore,再在我们的钱包中导入,调用上述web3j的 Wallet.decrypt(...)
基本会OOM Crash.
可以在 web3j Issues 中搜到大量相关的问题 , 解答基本是说依赖库不兼容Android导致的 . 这里就减少道友们绕圈子的时间了,直接提供个可行的解决方案.
Link: Out Of Memory exception when using web3j in Android
就是我们需要修改部分方法.
OOM优化
这里需要依赖
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implementation 'com.lambdaworks:scrypt:1.4.0' |
然后修改解密方法
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public static ECKeyPair decrypt(String password, WalletFile walletFile) throws CipherException { validate(walletFile); WalletFile.Crypto crypto = walletFile.getCrypto(); byte[] mac = Numeric.hexStringToByteArray(crypto.getMac()); byte[] iv = Numeric.hexStringToByteArray(crypto.getCipherparams().getIv()); byte[] cipherText = Numeric.hexStringToByteArray(crypto.getCiphertext()); byte[] derivedKey; if (crypto.getKdfparams() instanceof WalletFile.ScryptKdfParams) { WalletFile.ScryptKdfParams scryptKdfParams = (WalletFile.ScryptKdfParams) crypto.getKdfparams(); int dklen = scryptKdfParams.getDklen(); int n = scryptKdfParams.getN(); int p = scryptKdfParams.getP(); int r = scryptKdfParams.getR(); byte[] salt = Numeric.hexStringToByteArray(scryptKdfParams.getSalt()); // derivedKey = generateDerivedScryptKey(password.getBytes(Charset.forName("UTF-8")), salt, n, r, p, dklen); derivedKey = com.lambdaworks.crypto.SCrypt.scryptN(password.getBytes(Charset.forName("UTF-8")), salt, n, r, p, dklen); } else if (crypto.getKdfparams() instanceof WalletFile.Aes128CtrKdfParams) { WalletFile.Aes128CtrKdfParams aes128CtrKdfParams = (WalletFile.Aes128CtrKdfParams) crypto.getKdfparams(); int c = aes128CtrKdfParams.getC(); String prf = aes128CtrKdfParams.getPrf(); byte[] salt = Numeric.hexStringToByteArray(aes128CtrKdfParams.getSalt()); derivedKey = generateAes128CtrDerivedKey( password.getBytes(Charset.forName("UTF-8")), salt, c, prf); } else { throw new CipherException("Unable to deserialize params: " + crypto.getKdf()); } byte[] derivedMac = generateMac(derivedKey, cipherText); if (!Arrays.equals(derivedMac, mac)) { throw new CipherException("Invalid password provided"); } byte[] encryptKey = Arrays.copyOfRange(derivedKey, 0, 16); byte[] privateKey = performCipherOperation(Cipher.DECRYPT_MODE, iv, encryptKey, cipherText); return ECKeyPair.create(privateKey); } |
注释的代码行为 web3j 中的内容 ,到了这里我们还需要导入相应的so库,我们在src/main
下创建jniLibs
,接着放入对应平台so
全部so笔者已上传到 Android scrypt so
现在调用的是修改后的方法 LWallet.decrypt(...)
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public Flowable<HLWallet> importKeystore(Context context, String keystore, String password) { return Flowable.just(keystore) .flatMap(s -> { ObjectMapper objectMapper = new ObjectMapper(); WalletFile walletFile = objectMapper.readValue(keystore, WalletFile.class); ECKeyPair keyPair = LWallet.decrypt(password, walletFile); HLWallet hlWallet = new HLWallet(walletFile); WalletFile generateWalletFile = Wallet.createLight(password, keyPair); if (!generateWalletFile.getAddress().equalsIgnoreCase(walletFile.getAddress())) { return Flowable.error(new HLError(ReplyCode.failure, new Throwable("address doesn't match private key"))); } if (WalletManager.shared().isWalletExist(hlWallet.getAddress())) { return Flowable.error(new HLError(ReplyCode.walletExisted, new Throwable("Wallet existed!"))); } WalletManager.shared().saveWallet(context, hlWallet); return Flowable.just(hlWallet); }); } |
Other FAQ
在开发中, 总是会有这样那样的疑问,这里做一个简单的答疑
Q. 怎么导出助记词啊 , imToken 有导出/备份助记词的功能 .
A. 很好的问题. 其实就是创建/用助记词解锁钱包时,app本地保存了助记词.导出只是将存储数据读取出来而已.可以尝试在imToken上通过导入Keystore或者私钥解锁钱包,就会发现没有备份助记词的入口.
Q. app本地需要保存钱包什么信息
A. 理论上说只需要保存钱包的Keystore.助记词,私钥最好别存,因为app一旦被破解,用户的钱包就能被直接获取到.如若有出于用户体验等原因保存这些敏感信息,最好结合用户输入的密码做对称加密保存.
…
以上即为以太坊解锁钱包的主要内容,过程中的坑基本有显式指明.
GitHub 系列教程代码已上传