(Excel) AES XTS Mode where Tweak Value is Data Unit Number

Demonstrates the AES-XTS mode of operation where the tweak value is specified as a data unit number.

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

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

' IEEE 1619 test vector 10

key = "2718281828459045235360287471352662497757247093699959574966967627"

tweakKey = "3141592653589793238462643383279502884197169399375105820974944592"
' The data unit number is 255
' We'll specify this numerically by calling XtsSetDataUnitNumber with 255, 0 (see below)

dataUnit = "00000000000000ff"

Dim bd As Chilkat.BinData
Set bd = Chilkat.NewBinData

Dim success As Boolean
success = bd.AppendEncoded("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f","hex")
success = bd.AppendEncoded("202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f","hex")
success = bd.AppendEncoded("404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f","hex")
success = bd.AppendEncoded("606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f","hex")
success = bd.AppendEncoded("808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9f","hex")
success = bd.AppendEncoded("a0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebf","hex")
success = bd.AppendEncoded("c0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedf","hex")
success = bd.AppendEncoded("e0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff","hex")
success = bd.AppendEncoded("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f","hex")
success = bd.AppendEncoded("202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f","hex")
success = bd.AppendEncoded("404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f","hex")
success = bd.AppendEncoded("606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f","hex")
success = bd.AppendEncoded("808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9f","hex")
success = bd.AppendEncoded("a0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebf","hex")
success = bd.AppendEncoded("c0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedf","hex")
success = bd.AppendEncoded("e0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff","hex")

Debug.Print "Size of plain-text: "; bd.NumBytes

' This is the expected ciphertext:
' cipherText =             "1c3b3a102f770386e4836c99e370cf9bea00803f5e482357a4ae12d414a3e63b"
'                        + "5d31e276f8fe4a8d66b317f9ac683f44680a86ac35adfc3345befecb4bb188fd"
'                        + "5776926c49a3095eb108fd1098baec70aaa66999a72a82f27d848b21d4a741b0"
'                        + "c5cd4d5fff9dac89aeba122961d03a757123e9870f8acf1000020887891429ca"
'                        + "2a3e7a7d7df7b10355165c8b9a6d0a7de8b062c4500dc4cd120c0f7418dae3d0"
'                        + "b5781c34803fa75421c790dfe1de1834f280d7667b327f6c8cd7557e12ac3a0f"
'                        + "93ec05c52e0493ef31a12d3d9260f79a289d6a379bc70c50841473d1a8cc81ec"
'                        + "583e9645e07b8d9670655ba5bbcfecc6dc3966380ad8fecb17b6ba02469a020a"
'                        + "84e18e8f84252070c13e9f1f289be54fbc481457778f616015e1327a02b140f1"
'                        + "505eb309326d68378f8374595c849d84f4c333ec4423885143cb47bd71c5edae"
'                        + "9be69a2ffeceb1bec9de244fbe15992b11b77c040f12bd8f6a975a44a0f90c29"
'                        + "a9abc3d4d893927284c58754cce294529f8614dcd2aba991925fedc4ae74ffac"
'                        + "6e333b93eb4aff0479da9a410e4450e0dd7ae4c6e2910900575da401fc07059f"
'                        + "645e8b7e9bfdef33943054ff84011493c27b3429eaedb4ed5376441a77ed4385"
'                        + "1ad77f16f541dfd269d50d6a5f14fb0aab1cbb4c1550be97f7ab4066193c4caa"
'                        + "773dad38014bd2092fa755c824bb5e54c4f36ffda9fcea70b9c6e693e148c151";

Dim crypt As Chilkat.Crypt2
Set crypt = Chilkat.NewCrypt2

crypt.CryptAlgorithm = "aes"
crypt.CipherMode = "xts"
crypt.KeyLength = 256

crypt.SetEncodedKey key,"hex"
crypt.XtsSetEncodedTweakKey tweakKey,"hex"

' Here we set the tweak value as a data unit number (a 64-bit integer passed in 2 32-bit values)
crypt.XtsSetDataUnitNumber 255,0

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

Debug.Print "CT = "; bd.GetEncoded("hexlower")

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

Debug.Print "PT = "; bd.GetEncoded("hexlower")