Generate Psuedo-Random Data using ARC4 as a PRNG

This example demonstrates how to use the ARC4 stream encryption algorithm as a pseudo-random number generator (PRNG). This example generates the random data as hex encoded strings. The EncryptStringENC method can be replaced with EncryptBytes to generate random bytes. Note: This example uses new features available in the pre-release, or any official new version released after 17-October-2007.

Download Chilkat Crypt ActiveX

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
Set outFile = fso.CreateTextFile("output.txt", True)

set crypt = CreateObject("Chilkat.Crypt2")

success = crypt.UnlockComponent("Anything for 30-day trial")
If (success <> 1) Then
    MsgBox "Crypt component unlock failed"
    WScript.Quit
End If

crypt.CryptAlgorithm = "arc4"
crypt.KeyLength = 128

crypt.SetEncodedKey "000102030405060708090A0B0C0D0E0F","hex"

crypt.EncodingMode = "hex"

'  We will repeatedly feed these 8-bytes of data to
'  the ARC4 stream encryptor to generate our pseudo-random
'  sequence.

strData = "012345678"

'  Set FirstChunk to 1 to initialize the ARC4 PRNG with the key.
crypt.FirstChunk = 1
crypt.LastChunk = 0

encryptedText = crypt.EncryptStringENC(strData)
outFile.WriteLine(encryptedText)

'  Set FirstChunk to 0 to continue encrypting
'  without re-initializing the ARC4 PRNG
crypt.FirstChunk = 0

For i = 1 To 16
    '  Repeatedly encrypting the same 8 bytes of data
    '  produces then pseudo-random sequence.
    encryptedText = crypt.EncryptStringENC(strData)
    outFile.WriteLine(encryptedText)
Next
outFile.Close