(Objective-C) 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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#import <NSString.h>
#import <CkoBinData.h>
#import <CkoCrypt2.h>

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

BOOL success;

// IEEE 1619 test vector 10
NSString *key = @"2718281828459045235360287471352662497757247093699959574966967627";
NSString *tweakKey = @"3141592653589793238462643383279502884197169399375105820974944592";
// The data unit number is 255
// We'll specify this numerically by calling XtsSetDataUnitNumber with 255, 0 (see below)
NSString *dataUnit = @"00000000000000ff";

CkoBinData *bd = [[CkoBinData alloc] init];

[bd AppendEncoded: @"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f" encoding: @"hex"];
[bd AppendEncoded: @"202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f" encoding: @"hex"];
[bd AppendEncoded: @"404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f" encoding: @"hex"];
[bd AppendEncoded: @"606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f" encoding: @"hex"];
[bd AppendEncoded: @"808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9f" encoding: @"hex"];
[bd AppendEncoded: @"a0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebf" encoding: @"hex"];
[bd AppendEncoded: @"c0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedf" encoding: @"hex"];
[bd AppendEncoded: @"e0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff" encoding: @"hex"];
[bd AppendEncoded: @"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f" encoding: @"hex"];
[bd AppendEncoded: @"202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f" encoding: @"hex"];
[bd AppendEncoded: @"404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f" encoding: @"hex"];
[bd AppendEncoded: @"606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f" encoding: @"hex"];
[bd AppendEncoded: @"808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9f" encoding: @"hex"];
[bd AppendEncoded: @"a0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebf" encoding: @"hex"];
[bd AppendEncoded: @"c0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedf" encoding: @"hex"];
[bd AppendEncoded: @"e0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff" encoding: @"hex"];

NSLog(@"%@%d",@"Size of plain-text: ",[bd.NumBytes intValue]);

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

CkoCrypt2 *crypt = [[CkoCrypt2 alloc] init];

crypt.CryptAlgorithm = @"aes";
crypt.CipherMode = @"xts";
crypt.KeyLength = [NSNumber numberWithInt:256];

[crypt SetEncodedKey: key encoding: @"hex"];
[crypt XtsSetEncodedTweakKey: tweakKey encoding: @"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 hiUint32: 0];

// In-place encrypt the contents of bd.
success = [crypt EncryptBd: bd];

NSLog(@"%@%@",@"CT = ",[bd GetEncoded: @"hexlower"]);

// Decrypt to revert back to the unencrypted content:
success = [crypt DecryptBd: bd];

NSLog(@"%@%@",@"PT = ",[bd GetEncoded: @"hexlower"]);