Generate Psuedo-Random Data using ARC4 as a PRNG

Download Chilkat Crypt ActiveX

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.

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