(Ruby) AES XTS Mode

Demonstrates the AES-XTS mode of operation.

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

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require 'chilkat'

# 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 = "394c97881abd989d29c703e48a72b397"
tweakKey = "a7acf51b59649eeea9b33274d8541df4"
dataUnit = "4b15c684a152d485fe9937d39b168c29"

bd = Chilkat::CkBinData.new()
bd.AppendEncoded("2f3b9dcfbae729583b1d1ffdd16bb6fe2757329435662a78f0","hex")

crypt = Chilkat::CkCrypt2.new()

crypt.put_CryptAlgorithm("aes")
crypt.put_CipherMode("xts")
crypt.put_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)

print "CT = " + bd.getEncoded("hexlower") + "\n";

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

print "PT = " + bd.getEncoded("hexlower") + "\n";

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