Encryption Decryption Errror

Danish Habib

Dear All I want to encrypt and decrypt a password while creating the user account, below is the code which i am using for encoding and decoding and while encoding mean creating the users my password saved into the encrypted form but while getting the values it gives an error on base64Decode the error is "nvalid length for a base-64 char array or string in base64 decode" below are my two methods and i am saving password "pak1234" in my password column

Private Function base64Encode(ByVal sData As String) As String
Try
Dim encData_byte As Byte() = New Byte(sData.Length - 1) {}
encData_byte = System.Text.Encoding.UTF8.GetBytes(sData)
Dim encodedData As String = Convert.ToBase64String(encData_byte)
Return (encodedData)
Catch ex As Exception
Throw (New Exception("Error in base64Encode" & ex.Message))
End Try
End Function
Public Function base64Decode(ByVal sData As String) As String
Dim encoder As New System.Text.UTF8Encoding()
Dim utf8Decode As System.Text.Decoder = encoder.GetDecoder()
Dim todecode_byte As Byte() = Convert.FromBase64String(sData)
Dim charCount As Integer = utf8Decode.GetCharCount(todecode_byte, 0, todecode_byte.Length)
Dim decoded_char As Char() = New Char(charCount - 1) {}
utf8Decode.GetChars(todecode_byte, 0, todecode_byte.Length, decoded_char, 0)
Dim result As String = New [String](decoded_char)
Return result
End Function

3 Replies

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Vulpes11y ago
As the encrypted password will be stored in the database, this is what the parameter needs to be set to when retrieving the user record.

So if you use the following when retrieving it should work:

cmdUser.Parameters.Add("@Password", SqlDbType.VarChar).Value = base64Encode(txtPassword.Text.Trim())

So you don't really need the base64Decode method at all unless, perhaps, you want to retrieve the actual password from the encrypted version because the user has forgotten it.
Danish Habib11y ago
Dear Vulpes thanks for response ,ON Saving i am passing password parameter as
.Add("@Password", SqlDbType.VarChar).Value = base64Encode(txtPassword.Text.Trim())

and while retriving i am using
cmdUser.Parameters.Add("@Password", SqlDbType.VarChar).Value = base64Decode(txtPassword.Text.Trim())
Vulpes11y ago
I placed those methods into a console application and tested it as follows:

Imports System

Class Test

Shared Sub Main
Dim t As New Test
Dim password As String = "pak1234"
Dim encoded As String = t.base64Encode(password)
Dim decoded As String = t.base64Decode(encoded)
Console.WriteLine("The decoded password is " + decoded)
Console.ReadKey
End Sub

Private Function base64Encode(ByVal sData As String) As String
Try
Dim encData_byte As Byte() = New Byte(sData.Length - 1) {}
encData_byte = System.Text.Encoding.UTF8.GetBytes(sData)
Dim encodedData As String = Convert.ToBase64String(encData_byte)
Return (encodedData)
Catch ex As Exception
Throw (New Exception("Error in base64Encode" & ex.Message))
End Try
End Function

Public Function base64Decode(ByVal sData As String) As String
Dim encoder As New System.Text.UTF8Encoding()
Dim utf8Decode As System.Text.Decoder = encoder.GetDecoder()
Dim todecode_byte As Byte() = Convert.FromBase64String(sData)
Dim charCount As Integer = utf8Decode.GetCharCount(todecode_byte, 0, todecode_byte.Length)
Dim decoded_char As Char() = New Char(charCount - 1) {}
utf8Decode.GetChars(todecode_byte, 0, todecode_byte.Length, decoded_char, 0)
Dim result As String = New [String](decoded_char)
Return result
End Function

End Class

However, the output was:

The decoded password is pak1234

and when I tried other passwords they also decoded correctly as well.

So are you sure you're passing the encoded string (rather than the original string) to the base64Decode method?