InvalidKeyException:在Android设备上对RSA decrypt执行密钥存储操作失败

Question

我正在尝试对AndroidKeyStore中的密钥执行RSA加密和解密。加密成功完成，但当我尝试解密时，它在Cipher.init()上抛出一个InvalidKeyException: Keystore操作失败。

以下是我的密钥生成代码：

KeyPairGenerator kpGenerator = KeyPairGenerator.getInstance("RSA", "AndroidKeyStore");
AlgorithmParameterSpec spec = null;
spec = new KeyGenParameterSpec.Builder(mAlias,
        KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
        .setDigests(KeyProperties.DIGEST_SHA256, KeyProperties.DIGEST_SHA512)
        .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_RSA_PKCS1)
        .build();
kpGenerator.initialize(spec);
KeyPair kp = kpGenerator.generateKeyPair();

这是我的加密代码：

KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);
KeyStore.PrivateKeyEntry entry = (KeyStore.PrivateKeyEntry) keyStore.getEntry(mAlias, null);
Cipher cip = null;
RSAPublicKey pubKey = (RSAPublicKey) entry.getCertificate().getPublicKey();
cip = Cipher.getInstance("RSA/ECB/NoPadding");
cip.init(Cipher.ENCRYPT_MODE, pubKey);
byte[] encryptBytes = cip.doFinal(challenge.getBytes());
String encryptedStr64 = Base64.encodeToString(encryptBytes, Base64.DEFAULT);

这是我的解密代码：

KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);
KeyStore.PrivateKeyEntry entry = (KeyStore.PrivateKeyEntry) keyStore.getEntry(mAlias, null);
Cipher cip = null;
cip = Cipher.getInstance("RSA/ECB/NoPadding");
cip.init(Cipher.DECRYPT_MODE, entry.getPrivateKey());
byte[] decryptedBytes = cip.doFinal(Base64.decode(encrypted64, Base64.DEFAULT));
String plainText = new String(decryptedBytes);

我知道密钥生成代码中的填充与我的加密/解密代码不同。但是，当我将密钥生成代码的填充改为KeyProperties.ENCRYPTION_PADDING_NONE时，我得到的是kpGenerator.initialize上的InvalidAlgorithmParameterException (Spec)。在decrypt中使用"RSA/ECB/PKCS1Padding“，它可以工作。无论加密中的填充是什么，它总是有效的。

是的，我也知道使用无填充的安全隐患，但对于我的应用程序，我需要一个确定性的密文。

下面是InvalidKeyException的堆栈跟踪：

03-06 09:10:32.710  5058  5058 W System.err: java.security.InvalidKeyException: Keystore operation failed
03-06 09:10:32.713  5058  5058 W System.err:    at android.security.KeyStore.getInvalidKeyException(KeyStore.java:692)
03-06 09:10:32.713  5058  5058 W System.err:    at android.security.KeyStore.getInvalidKeyException(KeyStore.java:712)
03-06 09:10:32.713  5058  5058 W System.err:    at android.security.keystore.KeyStoreCryptoOperationUtils.getInvalidKeyExceptionForInit(KeyStoreCryptoOperationUtils.java:54)
03-06 09:10:32.713  5058  5058 W System.err:    at android.security.keystore.KeyStoreCryptoOperationUtils.getExceptionForCipherInit(KeyStoreCryptoOperationUtils.java:89)
03-06 09:10:32.713  5058  5058 W System.err:    at android.security.keystore.AndroidKeyStoreCipherSpiBase.ensureKeystoreOperationInitialized(AndroidKeyStoreCipherSpiBase.java:263)
03-06 09:10:32.713  5058  5058 W System.err:    at android.security.keystore.AndroidKeyStoreCipherSpiBase.engineInit(AndroidKeyStoreCipherSpiBase.java:108)
03-06 09:10:32.713  5058  5058 W System.err:    at javax.crypto.Cipher.tryTransformWithProvider(Cipher.java:612)
03-06 09:10:32.713  5058  5058 W System.err:    at javax.crypto.Cipher.tryCombinations(Cipher.java:532)
03-06 09:10:32.714  5058  5058 W System.err:    at javax.crypto.Cipher.getSpi(Cipher.java:437)
03-06 09:10:32.714  5058  5058 W System.err:    at javax.crypto.Cipher.init(Cipher.java:815)
03-06 09:10:32.714  5058  5058 W System.err:    at javax.crypto.Cipher.init(Cipher.java:774)
03-06 09:10:32.714  5058  5058 W System.err:    at dfpidentifiers.my.test.app.MainActivity.decrypt(MainActivity.java:950)
03-06 09:10:32.714  5058  5058 W System.err:    at dfpidentifiers.my.test.app.MainActivity.onCreate(MainActivity.java:117)
03-06 09:10:32.714  5058  5058 W System.err:    at android.app.Activity.performCreate(Activity.java:6251)
03-06 09:10:32.714  5058  5058 W System.err:    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
03-06 09:10:32.714  5058  5058 W System.err:    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
03-06 09:10:32.714  5058  5058 W System.err:    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
03-06 09:10:32.714  5058  5058 W System.err:    at android.app.ActivityThread.-wrap11(ActivityThread.java)
03-06 09:10:32.714  5058  5058 W System.err:    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
03-06 09:10:32.714  5058  5058 W System.err:    at android.os.Handler.dispatchMessage(Handler.java:102)
03-06 09:10:32.714  5058  5058 W System.err:    at android.os.Looper.loop(Looper.java:148)
03-06 09:10:32.714  5058  5058 W System.err:    at android.app.ActivityThread.main(ActivityThread.java:5417)
03-06 09:10:32.714  5058  5058 W System.err:    at java.lang.reflect.Method.invoke(Native Method)
03-06 09:10:32.714  5058  5058 W System.err:    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
03-06 09:10:32.714  5058  5058 W System.err:    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
03-06 09:10:32.714  5058  5058 W System.err: Caused by: android.security.KeyStoreException: Incompatible padding mode
03-06 09:10:32.714  5058  5058 W System.err:    at android.security.KeyStore.getKeyStoreException(KeyStore.java:632)
03-06 09:10:32.714  5058  5058 W System.err:    ... 24 more

从堆栈跟踪来看，它似乎是一个不兼容的填充模式，但是我如何生成一个不支持填充的密钥对呢？

Answer 1

InvalidKeyException实际上是由密钥生成和解密过程中填充的差异造成的。我不确定为什么加密没有抛出同样的异常。

我最初也不能在密钥生成期间使用NoPadding，因为需要IND-CPA。我必须设置setRandomizedEncryptionRequired(true)来覆盖它。