Converting SHA-2 hash into alphanumeric hash (vb.net) - vb.net

Question

I have SHA-2 hash values. Here's an example:
qlbQbEd8khe2vEYG9acKScUiVTC6y1UorkMvptATwwxkVApkOCUH7hwkncbi2TY78HrIeC19G8EHlaAmj6sBAwCxhF2TeOpmJ1+2OfbfXF+jMWUO74O7WHJuwoq+R5aKa0c2QYbyrcd/DWSprdkrF1gyz+RWVXYQug63aAhC0j0=
I need to convert these into an alphanumeric hash — that is, using only capital letters and numbers ("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"). The process has to be reversible for SHA-2 hash comparison.
The reason for this conversion is aesthetics. The resulting hash will be used as a license key, and has to be shorter and more easily readable and typeable.
I read that I could try to re-encode that hash into Base36, but I have been unsuccessful. Can anyone give any suggestions?

Answer 1

This code is an example for converting Base36 to/from Base26
Const Base36 As String = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
Const Base26 As String = "abcdefghijklmnopqrstuvwxyz"
Function Num2Base(Vlu As Long, Base As String) As String
Dim A() As Integer = Nothing
Dim y As Integer = -1
Dim X As Long = Vlu
Dim Ln As Integer = Base.Length
Do While X > -1
y = y + 1
ReDim Preserve A(y)
A(y) = X Mod Ln
X = ((X - A(y)) / Ln) - 1
Loop
Dim res As String = ""
If y >= 0 Then
For Each d As Integer In A
res &= Mid(Base, d + 1, 1)
Next
End If
Return res
End Function
Function Base2Num(s As String, Base As String) As Long
If s.Length = 0 Then
Throw New Exception("'S' can not be empty")
End If
Dim res As Long = -1
Dim Ln As Integer = Base.Length
Dim x As Integer = 0
For Each c In s
res += (Base.IndexOf(c) + 1) * (Ln ^ x)
x += 1
Next
Return res
End Function
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim Num As Long = 1313
Dim b36 As String = Num2Base(Num, Base36) 'convert Num to base36
Dim b26 As String = Num2Base(Num, Base26) 'convert Num to base26
MessageBox.Show("Num:" & Num & vbCrLf & "ToBase36:" & b36 & vbCrLf & "ToBase26:" & b26, "Message 1")
Dim N36 As Long = Base2Num(b36, Base36) 'convert Base36 to Num
Dim N26 As Long = Base2Num(b26, Base26) 'convert Base26 to Num
MessageBox.Show("N36:" & N36 & vbCrLf & "N26:" & N26, "Message 2")
b26 = Num2Base(Base2Num(b36, Base36), Base26) 'convert Base36 to Base 26
MessageBox.Show("Base36 to Base 26 :" & b26, "Message 3")
b36 = Num2Base(Base2Num(b26, Base26), Base36) 'convert Base26 to Base 36
MessageBox.Show("Base26 to Base 36 :" & b36, "Message 4")
MessageBox.Show(Num2Base(1486154465904653, Base36), "Message 5")
End Sub
Unfortunately this code can not work with long strings(more than 12 chrs) due the limitation of the type Long,so you may need to split SHA-2 string to small parts