Android - javax.crypto.AEADBadTagException

Question

I'm currently getting an AEADBadTagException when trying to decrypt a file I have encrypted. I have searched pretty much everywhere on stackoverflow and unable to find a solution, and hoping there is just a small mistake I have made or something to do with encoding etc., since GCM is unable to verify the tag that it is generating.

I believe the problem is somewhere in the file I am trying to encrypt/decrypt. The same exact code works on an image, however, when I try to encrypt a PDF, it fails and gives me the above error.

The code below is not using CipherOutputStream/CipherInputStream, but I have tried it with both with no luck.

I understand that it the encryption/decryption methods should not be written like this, especially with the hardcoded IVs, but right now I am just trying to get it to work, then properly securing these methods later.

I am using Android KeyStore to get my secret key. I know this part works since I have lots of other pieces in the app using the Keystore with the same methods. Plus, this methods works with an image.

The error is happening on cipher.doFinal(encryptedBytes). When I use CipherInputStream, it happens on CipherInputStream(EncryptedFileStream, cipher)

Here is the code as well as the error stack, any help is greatly appreciated:

Encryption

        val fileBytes = inputStream.readBytes()
        val cipher = Cipher.getInstance("AES/GCM/NoPadding")
        keyStoreService.checkKeyAndCreate(ALIAS_FILE_KEY)
        val key = keyStoreService.getFileKey(ALIAS_FILE_KEY)
        val iv = byteArrayOf(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
        cipher.init(Cipher.ENCRYPT_MODE, key, GCMParameterSpec(128, iv))
        val encryptedBytes = cipher.doFinal(fileBytes)
        outputStream = FileOutputStream(file)
        outputStream.write(encryptedBytes)
        outputStream.flush()
        inputStream.close()
        outputStream.close()

Decryption

    val encryptedFile = File(filePath)
    val encryptedBytes = encryptedFile.readBytes()
    val cipher = Cipher.getInstance("AES/GCM/NoPadding")
    val key = keyStoreService.getFileKey(ALIAS_FILE_KEY)
    val iv = byteArrayOf(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
    cipher.init(Cipher.DECRYPT_MODE, key, GCMParameterSpec(128, iv))
    val decryptedBytes = cipher.doFinal(encryptedBytes)

    return ByteArrayInputStream(decryptedBytes)

Stacktrace

E/AndroidRuntime: FATAL EXCEPTION: main
Process: onboard.app.passageways, PID: 15441
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:503)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
 Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
 Caused by: javax.crypto.AEADBadTagException
    at android.security.keystore.AndroidKeyStoreCipherSpiBase.engineDoFinal(AndroidKeyStoreCipherSpiBase.java:517)
    at javax.crypto.Cipher.doFinal(Cipher.java:2055)
    at passageways.android.onboard.services.EncryptionService.readEncryptedFile(EncryptionService.kt:79)
    at passageways.android.onboard.fragments.MeetingBookDialogFragment.onViewCreated(Fragment.kt:38)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1471)
    at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
    at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:802)
    at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
    at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
    at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273)
    at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:733)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6669)
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
 Caused by: android.security.KeyStoreException: Signature/MAC verification failed
    at android.security.KeyStore.getKeyStoreException(KeyStore.java:839)
    at android.security.keystore.KeyStoreCryptoOperationChunkedStreamer.doFinal(KeyStoreCryptoOperationChunkedStreamer.java:224)
    at android.security.keystore.AndroidKeyStoreAuthenticatedAESCipherSpi$BufferAllOutputUntilDoFinalStreamer.doFinal(AndroidKeyStoreAuthenticatedAESCipherSpi.java:373)
    at android.security.keystore.AndroidKeyStoreCipherSpiBase.engineDoFinal(AndroidKeyStoreCipherSpiBase.java:506)
    at javax.crypto.Cipher.doFinal(Cipher.java:2055) 
    at passageways.android.onboard.services.EncryptionService.readEncryptedFile(EncryptionService.kt:79) 
    at passageways.android.onboard.fragments.MeetingBookDialogFragment.onViewCreated(Fragment.kt:38) 
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1471) 
    at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784) 
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852) 
    at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:802) 
    at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625) 
    at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411) 
    at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366) 
    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273) 
    at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:733) 
    at android.os.Handler.handleCallback(Handler.java:873) 
    at android.os.Handler.dispatchMessage(Handler.java:99) 
    at android.os.Looper.loop(Looper.java:193) 
    at android.app.ActivityThread.main(ActivityThread.java:6669)

Orten

Convert Base64 before save. see this – Gainor

@kelalaka: There's no reason to base64 encode that I can see. – Dowland

@kelalaka, I think James is right. I'm not trying to encrypt a string then save it. I just want to encrypt the raw bytes from the files. Since it works with images, I don't think base64 is the issue. I'm curious as to if maybe somehow PDF data is messing with the tag that is being generated by the cipher? I did check the length of both the encrypted data that is written, and the encrypted data that is read when decrypting, and they are the same length. I'll do a check if it's the same data tommorrow. – Orten

Answer 1

Turns out readBytes() uses a default buffer size, and only returns a byte buffer that is the length of that. So it was not actually returning me the whole file in bytes, just up to the length of the buffer.

I have switched to using a CipherOutputStream, be sure to include flush() after writing your contents to the tag will be included!

Orten

Answer 2

i got the same error,finnaly i found the answer. when i encrypt(data1) and encrypt(data2),i want get the data1 by decrypt(data1.encryptStr),i got this problem(Caused by: android.security.KeyStoreException: Signature/MAC verification failed). so ,if you upload 2 files,you couldn`t get this first file by decrypt it

Incurve

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