PureBasic

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.

PureBasic

IncludeFile "CkBinData.pb"
IncludeFile "CkCrypt2.pb"

Procedure ChilkatExample()

    success.i = 0

    ; 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))

    key.s = "394c97881abd989d29c703e48a72b397"
    tweakKey.s = "a7acf51b59649eeea9b33274d8541df4"
    dataUnit.s = "4b15c684a152d485fe9937d39b168c29"

    bd.i = CkBinData::ckCreate()
    If bd.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkBinData::ckAppendEncoded(bd,"2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0","hex")

    crypt.i = CkCrypt2::ckCreate()
    If crypt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkCrypt2::setCkCryptAlgorithm(crypt, "aes")
    CkCrypt2::setCkCipherMode(crypt, "xts")
    CkCrypt2::setCkKeyLength(crypt, 128)

    CkCrypt2::ckSetEncodedKey(crypt,key,"hex")
    CkCrypt2::ckXtsSetEncodedTweakKey(crypt,tweakKey,"hex")
    CkCrypt2::ckXtsSetEncodedTweakValue(crypt,dataUnit,"hex")

    ; In-place encrypt the contents of bd.
    success = CkCrypt2::ckEncryptBd(crypt,bd)

    Debug "CT = " + CkBinData::ckGetEncoded(bd,"hexlower")

    ; Decrypt to revert back to the unencrypted content:
    success = CkCrypt2::ckDecryptBd(crypt,bd)

    Debug "PT = " + CkBinData::ckGetEncoded(bd,"hexlower")

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


    CkBinData::ckDispose(bd)
    CkCrypt2::ckDispose(crypt)


    ProcedureReturn
EndProcedure