(Objective-C) AES-CMAC

Demonstrates using the AES-CMAC algorithm, which is a keyed hash function similar to HMAC and Poly1305.

Note: Chilkat added AES-CMAC in version 9.5.0.95.

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#import <CkoCrypt2.h>
#import <NSString.h>
#import <CkoBinData.h>

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

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

// Set the MAC algorithm to AES-CMAC
crypt.MacAlgorithm = @"aes-cmac";

// AES-CMAC always uses a 16-byte (128-bit) MAC key.
NSString *keyHex = @"2b7e151628aed2a6abf7158809cf4f3c";
BOOL success = [crypt SetMacKeyEncoded: keyHex encoding: @"hex"];

// Let's compute the AES-CMAC for the test vector at https://www.rfc-editor.org/rfc/rfc4493#appendix-A
// Here we have 64 bytes in hex representation.
NSString *messageBytes = @"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710";

CkoBinData *bd = [[CkoBinData alloc] init];
[bd AppendEncoded: messageBytes encoding: @"hex"];

// Compute the AES-CMAC for the bytes contained in bd and return the AES-CMAC in hex representation.
crypt.EncodingMode = @"hex_lower";
NSString *cmac = [crypt MacBdENC: bd];
NSLog(@"%@",cmac);
// Output should be: 51f0bebf7e3b9d92fc49741779363cfe

// Now do the same for a string:
NSString *plainText = @"'Twas brillig, and the slithy toves\nDid gyre and gimble in the wabe:\nAll mimsy were the borogoves,\nAnd the mome raths outgrabe.";
NSString *encTag = [crypt MacStringENC: plainText];
NSLog(@"%@",encTag);

// Output should be: 4fca1fcbd265048d247f99ab57fa3ceb