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B4J Question B4XEncryption Decryption help needed [Solved]

Discussion in 'B4J Questions' started by Anser, Mar 7, 2018.

  1. Anser

    Anser Well-Known Member Licensed User

    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

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

    Sub DecryptText(EncryptedData() As Byte, password As StringAs 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
    Code:
    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
    Code:
    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 StringAs 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
     
    Last edited: Mar 7, 2018
  2. Anser

    Anser Well-Known Member Licensed User

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

    OliverA Expert Licensed User

    My 1 cent of input:

    Do not pass username/password in the URL. URL's are often logged. POST the username/password.
     
    Anser, udg and alwaysbusy like this.
  4. Anser

    Anser Well-Known Member Licensed User

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