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

LOCAL loCrypt
LOCAL lnSuccess
LOCAL lcStrData
LOCAL lcEncryptedText
LOCAL i

loCrypt = CreateObject('Chilkat.Crypt2')

lnSuccess = loCrypt.UnlockComponent("Anything for 30-day trial")
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX("Crypt component unlock failed")
    QUIT
ENDIF

loCrypt.CryptAlgorithm = "arc4"
loCrypt.KeyLength = 128

loCrypt.SetEncodedKey("000102030405060708090A0B0C0D0E0F","hex")

loCrypt.EncodingMode = "hex"

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

lcStrData = "012345678"

*  Set FirstChunk to 1 to initialize the ARC4 PRNG with the key.
loCrypt.FirstChunk = 1
loCrypt.LastChunk = 0

lcEncryptedText = loCrypt.EncryptStringENC(lcStrData)
? lcEncryptedText

*  Set FirstChunk to 0 to continue encrypting
*  without re-initializing the ARC4 PRNG
loCrypt.FirstChunk = 0

FOR i = 1 TO 15
    *  Repeatedly encrypting the same 8 bytes of data
    *  produces then pseudo-random sequence.
    lcEncryptedText = loCrypt.EncryptStringENC(lcStrData)
    ? lcEncryptedText
NEXT