B4X

AES XTS Mode

See more Encryption Examples

Demonstrates the AES-XTS mode of operation.

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

B4X

Dim success As Boolean = 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))

Dim key As String = "394c97881abd989d29c703e48a72b397"
Dim tweakKey As String = "a7acf51b59649eeea9b33274d8541df4"
Dim dataUnit As String = "4b15c684a152d485fe9937d39b168c29"

Dim bd As ChilkatBinData
bd.Initialize
bd.AppendEncoded("2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0", "hex")

Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")

crypt.CryptAlgorithm = "aes"
crypt.CipherMode = "xts"
crypt.KeyLength = 128

crypt.SetEncodedKey(key, "hex")
crypt.XtsSetEncodedTweakKey(tweakKey, "hex")
crypt.XtsSetEncodedTweakValue(dataUnit, "hex")

'  In-place encrypt the contents of bd.
success = crypt.EncryptBd(bd)

Log("CT = " & bd.GetEncoded("hexlower"))

'  Decrypt to revert back to the unencrypted content:
success = crypt.DecryptBd(bd)

Log("PT = " & bd.GetEncoded("hexlower"))

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