B4J Question B4XEncryption Decryption help needed [Solved]

[Anser]

Hi,

I am trying to use B4XEncryption and Decryption.

I Encrypt some data in B4A app and I expect B4J ABMaterial application to decrypt and use.

I am using the following Subs provided by Erel to Encrypt and Decrypt

Sub EncryptText(text As String, password As String) As Byte()
    Dim c As B4XCipher
    Return c.Encrypt(text.GetBytes("utf8"), password)
End Sub

Sub DecryptText(EncryptedData() As Byte, password As String) As String
    Dim c As B4XCipher
    Dim b() As Byte = c.Decrypt(EncryptedData, password)
    Return BytesToString(b, 0, b.Length, "utf8")
End Sub

From my B4A App I encrypt the username and password and then call a WebUrl that contains the encrypted username and password. The Web application is developed using ABMaterial.

For eg. Here is the B4A code where I Encrypt the data

Dim encryptedUserName() As Byte = EncryptText(Starter.cUserName.Trim, "123456") ' Returns encrypted data as bytes array
Dim encryptedPassword() As Byte = EncryptText(Starter.cPassword.Trim, "123456") ' Returns encrypted data as bytes array

 ' To pass the encrypted data along with the URL, convert it into string 
encryptedUserNameString = su.EncodeUrl( su.EncodeBase64(encryptedUserName), "UTF8" )
encryptedPasswordString = su.EncodeUrl( su.EncodeBase64(encryptedPassword), "UTF8" )

' The Web URL is created here
cWebAddress = "http://192.168.0.154:5100/MyApp/HomePage/?username=" & encryptedUserNameString & "&password=" & encryptedPasswordString

'Using a WebView, the ABMaterial app is invoked with the above URL

Now here is the B4J (ABMaterial) code where I receive the Parameters ie the username and password as encrypted data and then I try to decrypt it here using the same DeCryptText Sub

Dim cUserName as String
Dim cPassword as String
Dim su As StringUtils

'Please note ws is WebSocket in ABMaterial application
  
Dim cTemp() As Byte = su.DecodeBase64( su.DecodeUrl( ws.UpgradeRequest.GetParameter("username") , "UTF8" ) )
cUserName = DecryptText(  cTemp , "123456")

Dim cTemp() As Byte = su.DecodeBase64( su.DecodeUrl( ws.UpgradeRequest.GetParameter("password"), "UTF8" ) )
cPassword = DecryptText(  cTemp , "123456")

Sub DecryptText(EncryptedData() As Byte, password As String) As String
   Dim c As B4XCipher
   Dim b() As Byte = c.Decrypt(EncryptedData,password)
   Return BytesToString(b, 0, b.Length, "utf8")
End Sub

Unfortunately, when I decrypt the encrypted data in the B4J ABMaterial application, I get the following run time error. I could not find a solution and do not know where I have gone wrong.

The run time error is as follows org.bouncycastle.crypto.DataLengthException: last block incomplete in decryption

Websocket first connection
java.lang.RuntimeException: org.bouncycastle.crypto.DataLengthException: last block incomplete in decryption
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:119)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:77)
at anywheresoftware.b4j.object.WebSocketModule$Adapter$ThreadHandler.run(WebSocketModule.java:188)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.bouncycastle.crypto.DataLengthException: last block incomplete in decryption
at org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher.doFinal(Unknown Source)
at anywheresoftware.b4x.object.B4XEncryption.Decrypt(B4XEncryption.java:73)
at com.ab.template.homepage._decrypttext(homepage.java:427)
at com.ab.template.homepage._connectpage(homepage.java:399)
at com.ab.template.homepage._websocket_connected(homepage.java:894)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:90)
... 7 more
Disconnected

Any help will be appreciated

 

[Anser]

Solved.

The problem was that, inside the B4J app, to decrypt, I was calling su.DecodeURL, which was not required
The correct code in B4J to decrypt the value should be

Dim cTemp() As Byte = su.DecodeBase64(  ws.UpgradeRequest.GetParameter("username")  )
cUserName = DecryptText(  cTemp , "123456")

 

[OliverA]

My 1 cent of input:

Do not pass username/password in the URL. URL's are often logged. POST the username/password.

 

[Anser]

Yes I was also thinking on that line, but do not know where to start.

I am starting a new question on how to use http POST to start/call ABMaterial Webapp in the following thread
https://www.b4x.com/android/forum/t...name-and-password-to-abmaterial-webapp.90387/