String To Hex and Hex to String - vb.net

Question

I am able to convert my string to hex value but unable to do the opposite method:
Public Function StringToHex(_str$)
Return BitConverter.ToString(Convert.FromBase64String(_str$))
End Function
Public Function HexToString(_str$)
'could not do this
End Function
Private Sub Button55_Click(sender As Object, e As EventArgs) Handles
Button55.Click
lblStatus.Text = StringToHex("mankat236598")
'result : 99-A9-E4-6A-DD-B7-EB-9F-7C
lblInfo.Text = HexToString( lblStatus.Text)
'i want result : mankat236598
End Sub

Answer 1

As you have a string representation of bytes in a format "00-00-00", you need to convert the "00" etc. to bytes. You can skip the dashes while doing that:
Option Infer On
Option Strict On
Module Module1
Function StringToHex(s As String) As String
Return BitConverter.ToString(Convert.FromBase64String(s))
End Function
''' <summary>
''' Convert hex string to bytes and then Base64 encode those bytes.
''' </summary>
''' <param name="hexString">Hex as a string with dashes between bytes, e.g. A0-10-FF.</param>
''' <returns></returns>
Function HexToString(hexString As String) As String
Dim nBytes = (hexString.Length + 1) \ 3
Dim bb(nBytes - 1) As Byte
For i = 0 To nBytes - 1
Dim b = hexString.Substring(i * 3, 2)
bb(i) = Convert.ToByte(b, 16)
Next
Return Convert.ToBase64String(bb, Base64FormattingOptions.None)
End Function
Sub Main()
Dim testString = "mankat236598"
Dim x = StringToHex(testString)
Console.WriteLine(x)
Dim y = HexToString(x)
' Check if the result is correct:
If y <> testString Then Console.WriteLine("Round-trip failure.")
Console.WriteLine(y)
Console.ReadLine()
End Sub
End Module