Ported C# namespace to VB

PasswordStorage.vb

@@ -0,0 +1,162 @@
+Imports System
+Imports System.Text
+Imports System.Security.Cryptography
+
+Namespace PasswordSecurity
+
+    Class InvalidHashException
+        Inherits Exception
+
+        ' Default constructor
+        Sub New()
+        End Sub
+
+        Sub New(message As String)
+            MyBase.New(message)
+        End Sub
+
+        Sub New(message As String, innerException As Exception)
+            MyBase.New(message, innerException)
+        End Sub
+
+    End Class
+
+    Class CannotPerformOperationException
+        Inherits Exception
+
+        ' Default constructor
+        Sub New()
+        End Sub
+
+        Sub New(message As String)
+            MyBase.New(message)
+        End Sub
+
+        Sub New(message As String, innerException As Exception)
+            MyBase.New(message, innerException)
+        End Sub
+    End Class
+
+    Public Class PasswordStorage
+
+        'These constants may be changed without breaking existing hashes.
+        Public Const SALT_BYTES As Integer = 24
+        Public Const HASH_BYTES As Integer = 18
+        Public Const PBKDF2_ITERATIONS As Integer = 64000
+
+        ' These constants define the encoding And may Not be changed.
+        Public Const HASH_SECTIONS As Integer = 5
+        Public Const HASH_ALGORITHM_INDEX As Integer = 0
+        Public Const ITERATION_INDEX As Integer = 1
+        Public Const HASH_SIZE_INDEX As Integer = 2
+        Public Const SALT_INDEX As Integer = 3
+        Public Const PBKDF2_INDEX As Integer = 4
+
+        Public Shared Function CreateHash(password As String) As String
+
+            Dim salt(SALT_BYTES) As Byte
+            Try
+
+                Using csprng = New RNGCryptoServiceProvider()
+                    csprng.GetBytes(salt)
+                End Using
+
+            Catch ex As CryptographicException
+                Throw New CannotPerformOperationException("Random number generator not available", ex)
+            Catch ex As ArgumentException
+                Throw New CannotPerformOperationException("Invalid argument given to random number generator", ex)
+            End Try
+
+            Dim hash() As Byte = PBKDF2(password, salt, PBKDF2_ITERATIONS, HASH_BYTES)
+
+            ' format: algorithm:iteration:hashSize:salt:hash
+            Dim parts As String = "sha1:" + PBKDF2_ITERATIONS.ToString() + ":" + hash.Length.ToString() + ":" + Convert.ToBase64String(salt) + ":" + Convert.ToBase64String(hash)
+            Return parts
+
+        End Function
+
+        Public Shared Function VerifyPassword(password As String, goodHash As String) As Boolean
+            Dim delimter() As Char = {":"}
+            Dim split As String() = goodHash.Split(delimter)
+
+            If split.Length <> HASH_SECTIONS Then
+                Throw New InvalidHashException("Fields are missing from the password hash")
+            End If
+
+            ' We only support SHA1 with VB.NET
+            If split(HASH_ALGORITHM_INDEX) <> "sha1" Then
+                Throw New CannotPerformOperationException("Unsupported hash type.")
+            End If
+
+            Dim iterations As Integer = 0
+            Try
+                iterations = Integer.Parse(split(ITERATION_INDEX))
+            Catch ex As ArgumentException
+                Throw New CannotPerformOperationException("Invalid argument given to Int32.Parse", ex)
+            Catch ex As FormatException
+                Throw New InvalidHashException("Could not parse the iteration count as an integer.", ex)
+            Catch ex As OverflowException
+                Throw New InvalidHashException("The iteration count is too large to be represented.", ex)
+            End Try
+
+            If iterations < 1 Then
+                Throw New InvalidHashException("Invalid number of interations. Must be >= 1.")
+            End If
+
+            Dim salt() As Byte = Nothing
+            Try
+                salt = Convert.FromBase64String(split(SALT_INDEX))
+            Catch ex As ArgumentException
+                Throw New CannotPerformOperationException("Invalid argument given to Convert.FromBase64String.", ex)
+            Catch ex As FormatException
+                Throw New InvalidHashException("Base64 decoding of salt failed.", ex)
+            End Try
+
+            Dim hash() As Byte = Nothing
+            Try
+                hash = Convert.FromBase64String(split(PBKDF2_INDEX))
+            Catch ex As ArgumentException
+                Throw New CannotPerformOperationException("Invalid argument given to Convert.FromBase64String.", ex)
+            Catch ex As FormatException
+                Throw New InvalidHashException("Base64 decoding of pbkdf2 output failed.", ex)
+            End Try
+
+            Dim storedHashSize As Integer = 0
+            Try
+                storedHashSize = Integer.Parse(split(HASH_SIZE_INDEX))
+            Catch ex As ArgumentException
+                Throw New CannotPerformOperationException("Invalid argument given to Integer.Parse.", ex)
+            Catch ex As FormatException
+                Throw New InvalidHashException("The hash size is too large to be represented.", ex)
+            End Try
+
+            If storedHashSize <> hash.Length Then
+                Throw New InvalidHashException("Hash length doesn't match stored hash length.")
+            End If
+
+            Dim testHash() As Byte = PBKDF2(password, salt, iterations, hash.Length)
+            Return SlowEquals(hash, testHash)
+        End Function
+
+        Private Shared Function SlowEquals(a() As Byte, b() As Byte) As Boolean
+            Dim diff As UInteger = CUInt(a.Length) Xor CUInt(b.Length)
+            Dim i = 0
+            While i < a.Length And i < b.Length
+                diff = diff Or CUInt(a(i) Xor b(i))
+                i = i + 1
+            End While
+            Return diff = 0
+        End Function
+
+        Private Shared Function PBKDF2(password As String, salt() As Byte, iterations As Integer, outputBytes As Integer)
+            Using pbkdf2DerivedBytes = New Rfc2898DeriveBytes(password, salt)
+                pbkdf2DerivedBytes.IterationCount = iterations
+                Return pbkdf2DerivedBytes.GetBytes(outputBytes)
+            End Using
+        End Function
+
+    End Class
+
+End Namespace
+
+