Android Question Conversion AES Encrypt Function (vb.net) to B4A Error

laomms

Member
Licensed User
the vb.net code as below:

B4X:
Dim sKy As String = "lkirwf897+22#bbtrm8814z5qq=498j5"  '32 chr shared ascii string (32 * 8 = 256 bit)
Dim sIV As String = "741952hheeyy66#cs!9hjv887mxx7@8y"  '32 chr shared ascii string (32 * 8 = 256 bit)
Public Function EncryptRJ256(ByVal prm_key As String, ByVal prm_iv As String, ByVal prm_text_to_encrypt As String)

        Dim sToEncrypt As String = prm_text_to_encrypt

        Dim myRijndael As New RijndaelManaged
        myRijndael.Padding = PaddingMode.Zeros
        myRijndael.Mode = CipherMode.CBC
        myRijndael.KeySize = 256
        myRijndael.BlockSize = 256

        Dim encrypted() As Byte
        Dim toEncrypt() As Byte
        Dim key() As Byte
        Dim IV() As Byte

        key = System.Text.Encoding.UTF8.GetBytes(prm_key)
        IV = System.Text.Encoding.UTF8.GetBytes(prm_iv)

        Dim encryptor As ICryptoTransform = myRijndael.CreateEncryptor(key, IV)

        Dim msEncrypt As New MemoryStream()
        Dim csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)

        toEncrypt = System.Text.Encoding.UTF8.GetBytes(sToEncrypt)

        csEncrypt.Write(toEncrypt, 0, toEncrypt.Length)
        csEncrypt.FlushFinalBlock()

        encrypted = msEncrypt.ToArray()

        Return (Convert.ToBase64String(encrypted))

    End Function
    Public Function DecryptRJ256(ByVal prm_key As String, ByVal prm_iv As String, ByVal prm_text_to_decrypt As String)

        Dim sEncryptedString As String = prm_text_to_decrypt

        Dim myRijndael As New RijndaelManaged
        myRijndael.Padding = PaddingMode.Zeros
        myRijndael.Mode = CipherMode.CBC
        myRijndael.KeySize = 256
        myRijndael.BlockSize = 256

        Dim key() As Byte
        Dim IV() As Byte

        key = System.Text.Encoding.UTF8.GetBytes(prm_key)
        IV = System.Text.Encoding.UTF8.GetBytes(prm_iv)

        Dim decryptor As ICryptoTransform = myRijndael.CreateDecryptor(key, IV)

        Dim sEncrypted As Byte() = Convert.FromBase64String(sEncryptedString)

        Dim fromEncrypt() As Byte = New Byte(sEncrypted.Length) {}

        Dim msDecrypt As New MemoryStream(sEncrypted)
        Dim csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)

        csDecrypt.Read(fromEncrypt, 0, fromEncrypt.Length)

        Return (System.Text.Encoding.UTF8.GetString(fromEncrypt))

    End Function
I search forum found this:

B4X:
Sub AES_Encrypt(input As String, IV As String, pass As String) As String
    Dim  su As StringUtils
    Dim inputB() As Byte = input.GetBytes("UTF8")
    Dim passB() As Byte = pass.GetBytes("UTF8")
    Dim IVb() As Byte = IV.GetBytes("UTF8")
 
    Dim kg As KeyGenerator
    Dim C As Cipher
 
    kg.Initialize("AES") 'Yes, AES only
    kg.KeyFromBytes(passB)
 
    C.Initialize("AES/CBC/PKCS5Padding")
    C.InitialisationVector = IVb
 
    Dim datas() As Byte = C.Encrypt(inputB, kg.Key, True)
    Return su.EncodeBase64(datas)
End Sub
When I use :
B4X:
    Dim IV As String ="lkirwf897+22#bbtrm8814z5qq=498j5"  '
    Dim PWC As String = "741952hheeyy66#cs!9hjv887mxx7@8y"
    AES_Encrypt("ABC",IV,PWC)
It occurr error in line ; Dim datas() As Byte = C.Encrypt(inputB, kg.Key, True)
java.security.InvalidAlgorithmParameterException: expected IV length of 16 but was 32
 
Last edited:

laomms

Member
Licensed User
how to change IV length to 32.
the only way is modify server's IV length to 16 ?
 
Last edited:

laomms

Member
Licensed User
I modify vb.net to AES128, now is new problem, after encrypt string, there are only half string is samed:
B4A:
6YWyvhVsEzjC06wMKEBplbnV8ZdbGGIWsZt/Bt2+9q4=

VB.NET:
6YWyvhVsEzjC06wMKEBplYH+tqrQnKWxcP3UFHta4XM=
 

laomms

Member
Licensed User
vb.net modify block to 16 byte,modify keysize 32byte :

Dim sIV As String = "741952hheeyy66#c"
BlockSize = 128
KeySize=256

same result:
rO7rmJV/x0ZAjd/FbrlBr02Zm+RXml7DyWDyudBrqA0=
rO7rmJV/x0ZAjd/FbrlBr/N7oGhKXvnijh7y3Lox430=
half diffrent
 
Last edited:
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