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AES XTS Mode

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Demonstrates the AES-XTS mode of operation.

Note: This example requires Chilkat v9.5.0.91 or greater.

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Local $bSuccess = False

; This example assumes the Chilkat API to have been previously unlocked.
; See Global Unlock Sample for sample code.

; Here we have a sample from CAVS validatition data:

; COUNT = 301
; DataUnitLen = 200
; Key = 
; 394c97881abd989d29c703e48a72b397
; a7acf51b59649eeea9b33274d8541df4
; i = 4b15c684a152d485fe9937d39b168c29
; PT = 2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0
; CT = f3473802e38a3ffef4d4fb8e6aa266ebde553a64528a06463e

; Note: The above sample requires an AES-XTS implementation that fully supports ciphertext-stealing
; because the data to be encrypted is not an even multiple of the AES block size (i.e. not a multiple of 16 bytes).
; Chilkat fully supports AES-XTS with ciphertext stealing.
; (i.e. Chilkat implements XEX-based tweaked-codebook mode with ciphertext stealing (XTS))

Local $sKey = "394c97881abd989d29c703e48a72b397"
Local $sTweakKey = "a7acf51b59649eeea9b33274d8541df4"
Local $sDataUnit = "4b15c684a152d485fe9937d39b168c29"

$oBd = ObjCreate("Chilkat.BinData")
$oBd.AppendEncoded("2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0","hex")

$oCrypt = ObjCreate("Chilkat.Crypt2")

$oCrypt.CryptAlgorithm = "aes"
$oCrypt.CipherMode = "xts"
$oCrypt.KeyLength = 128

$oCrypt.SetEncodedKey $sKey,"hex"
$oCrypt.XtsSetEncodedTweakKey $sTweakKey,"hex"
$oCrypt.XtsSetEncodedTweakValue $sDataUnit,"hex"

; In-place encrypt the contents of bd.
$bSuccess = $oCrypt.EncryptBd($oBd)

ConsoleWrite("CT = " & $oBd.GetEncoded("hexlower") & @CRLF)

; Decrypt to revert back to the unencrypted content:
$bSuccess = $oCrypt.DecryptBd($oBd)

ConsoleWrite("PT = " & $oBd.GetEncoded("hexlower") & @CRLF)

; Output:
; CT = f3473802e38a3ffef4d4fb8e6aa266ebde553a64528a06463e
; PT = 2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0