Android Question VB6 function to decrypt AES-text from b4a

[Michael Müller Anywhere]

Hello,
I want to decrypt a string I have encrypted before in b4a and send it to a VB6-application via TCI/IP.
This is my code:

Sub AES_encrypt(was As String) As String
Dim PW = "myPW1234561234567890123456789012" As String
Dim salt = "1234567890123456" As String
Dim IV = "IV98765432109876" As String   

    Return my_encrypt( was.GetBytes("UTF8"), PW.GetBytes("UTF8"), salt.GetBytes("UTF8"), IV.GetBytes("UTF8"),  True)
End Sub


Sub my_encrypt(data() As Byte, passB() As Byte, SaltB() As Byte, IVb() As Byte, ReturnB64String As Boolean) As Object
Dim su As StringUtils
Dim kg As KeyGenerator
Dim C As Cipher
 
    kg.Initialize("AES")
    kg.KeyFromBytes(passB)
 
    C.Initialize("AES/CBC/PKCS5Padding")
    C.InitialisationVector = IVb
 
    Dim datas() As Byte = C.Encrypt(data, kg.Key, True)

    Dim SaltIVMessage(SaltB.Length + datas.Length) As Byte = AddSaltIVMessage(SaltB,IVb, datas)

    Log("Länge=" & (SaltB.Length + datas.Length + IVb.Length))
    
    If ReturnB64String Then
        Return su.EncodeBase64(SaltIVMessage)
    Else
        Return SaltIVMessage
    End If


End Sub

Private Sub AddSaltIVMessage (Salt() As Byte,IV() As Byte, Message () As Byte) As Byte()
Dim bc As ByteConverter
Dim SaltIVMessageBytes (Salt.Length + IV.Length + Message.Length) As Byte

    bc.ArrayCopy(Salt,0,SaltIVMessageBytes,0,32)
    bc.ArrayCopy(IV,0,SaltIVMessageBytes,32,16)
    bc.ArrayCopy(Message,0,SaltIVMessageBytes,48,Message.Length)

    
    Return SaltIVMessageBytes
End Sub

Does anyone know of a working function/solution for VB6 to decode the text?

I have allready tried in vain the "mdAesCtr.bas" module (over hours) from this side:

[VB6/VBA] Simple AES 256-bit password protected encryption-VBForums

Simple AES 256-bit password protected encryption A single mdAesCtr.bas module contains an implementation of a simple to use openssl compatible AES 256-bit encryption/decryption in Counter (CTR) mode, using CNG API functions available in Win7 and later. Sample usage Just copy/paste...

www.vbforums.com

But it seams then InitialisationVector in this module this is not taken into account.

Thank you!

 

[Hamied Abou Hulaikah]

See this:

AES Encrypt/Decrypt (Encryption/Decryption) B4A and B4J library

This library works with both B4A and B4J. Yes yes yes there are other ways to do this, this is how I do it. I have lots of small libraries that I use for myself, so I thought that I would share this one with the community. Hello fellow B4X'ers, I've decided to release this simple to use AES...

www.b4x.com

 

[Michael Müller Anywhere]

Thank you, but I am looking for a solution for VB6 to decode an aes-string

 

[MikeSW17]

Have you tried a web search? https://duckduckgo.com/?q=vb6+aes+decode&t=newext&atb=v271-1&ia=web
There's plenty of VB6 aes discussion out there.

Mighty glad to see VB6 is still out there!

 

[Michael Müller Anywhere]

My solution for everybody who's interested:
I use the crypt-activeX-component from "weonlydo.com".
The code is simple (salt is not nessesary):

Option Explicit
Dim DecryptedBlob As MemBlob
Dim EncryptedBlob As MemBlob
Dim Crypto As wodCryptCom
Public Function wod_decrypt(was As String) As String
    Crypto.LicenseKey = "xxxx-xxxx-xxxx-xxxx"
    Crypto.Optimized = False
    Crypto.SecretKey = "mysecretkey"
    Crypto.InitVector = "IV98765432109876"
    Crypto.mode = CBC
    Crypto.type = 4 'AES256
    EncryptedBlob.FromBase64 was
    Crypto.DeCrypt EncryptedBlob, DecryptedBlob
    wod_decrypt = Mid(DecryptedBlob.Text, Len(Crypto.InitVector) + 1)
End Function

I only have to remove the salt-part from the code above in my first thread:

Sub my_encrypt(data() As Byte, passB() As Byte, IVb() As Byte, ReturnB64String As Boolean) As Object
Dim su As StringUtils
Dim kg As KeyGenerator
Dim C As Cipher
 
    kg.Initialize("AES")
    kg.KeyFromBytes(passB)
    C.Initialize("AES/CBC/PKCS5Padding")
    C.InitialisationVector = IVb
 
    Dim datas() As Byte = C.Encrypt(data, kg.Key, True)
    Dim SaltIVMessage(IVb.Length + datas.Length) As Byte = AddNoSaltIVMessage(IVb, datas)
    
    If ReturnB64String Then
        Return su.EncodeBase64(SaltIVMessage)
    Else
        Return SaltIVMessage
    End If
End Sub

Private Sub AddNoSaltIVMessage (IV() As Byte, Message () As Byte) As Byte()
Dim bc As ByteConverter
    Dim SaltIVMessageBytes (IV.Length + Message.Length) As Byte
    bc.ArrayCopy(IV,0,SaltIVMessageBytes,0,16)
    bc.ArrayCopy(Message,0,SaltIVMessageBytes,16,Message.Length)
    Return SaltIVMessageBytes
End Sub