VB.NET

Duplicate .NET's Rfc2898DeriveBytes Functionality

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Demonstrates how to duplicate the results produced by .NET's System.Security.Cryptography.Rfc2898DeriveBytes class. VB.NET

' This example assumes Chilkat Crypt2 to have been previously unlocked.
' See Unlock Crypt2 for sample code.

' This example demonstrates how to duplicate the results produced
' by .NET's System.Security.Cryptography.Rfc2898DeriveBytes class.

' For example, here is C# code that transforms a password string into
' bytes that can be used as a secret key for symmetric encryption (such as AES, blowfish, 3DES, etc.)
' 
'     Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes("secret", System.Text.Encoding.UTF8.GetBytes("saltsalt123"), numIterations);
'     byte[] secretKeyBytes = deriveBytes.GetBytes(numBytes);

' (The Rfc2898DeriveBytes computation is really just the PBKDF2 algorithm with SHA-1 hashing.)
' In Chilkat, this is what we do to match...

' First, let's get a test vector with known results.  Both Chilkat AND Microsoft should produce
' the same results.  RFC 6070 has some PBKDF2 HMAC-SHA1 Test Vectors.  Here is one of them:

'      Input:
'        P = "passwordPASSWORDpassword" (24 octets)
'        S = "saltSALTsaltSALTsaltSALTsaltSALTsalt" (36 octets)
'        c = 4096
'        dkLen = 25
' 
'      Output:
'        DK = 3d 2e ec 4f e4 1c 84 9b
'             80 c8 d8 36 62 c0 e4 4a
'             8b 29 1a 96 4c f2 f0 70
'             38                      (25 octets)
' 
' 

Dim crypt As New Chilkat.Crypt2

Dim salt As String = "saltSALTsaltSALTsaltSALTsaltSALTsalt"
' Given that the salt is really binary data (can be any random bunch of bytes),
' we must pass the exact hex string representation of the salt bytes.
' In this case, we're getting the utf-8 byte representation of our salt string,
' which is identical to the us-ascii byte representation because there are no 8bit chars..
Dim saltHex As String = crypt.EncodeString(salt,"utf-8","hex")

' Duplicate the test vector as shown above.
Dim dkHex As String = crypt.Pbkdf2("passwordPASSWORDpassword","utf-8","sha1",saltHex,4096,25 * 8,"hex")
Debug.WriteLine(dkHex)