Objective-C

Example for both AES-128 and ChaCha20 to Encrypt Binary Data

See more Encryption Examples

Demonstrates the use of the new EncryptBd and DecryptBd methods introduced in Chilkat v9.5.0.67 to encrypt/decrypt binary bytes.

Note: This example requires Chilkat v9.5.0.67 or greater.

Objective-C

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

BOOL success = NO;

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

//  Load a small JPG file to be encrypted/decrypted.
CkoBinData *jpgBytes = [[CkoBinData alloc] init];
success = [jpgBytes LoadFile: @"qa_data/jpg/starfish.jpg"];
if (success != YES) {
    NSLog(@"%@",@"Failed to load JPG file.");
    return;
}

//  Show the unencrypted JPG bytes in Base64 format.
//  (The "base64_mime" encoding was added in Chilkat v9.5.0.67.
//  The "base64" encoding emits a single line of base64, whereas
//  "base64_mime" will emit multi-line base64 as it would appear
//  in MIME.)
NSLog(@"%@",[jpgBytes GetEncoded: @"base64_mime"]);

//  Sample base64_mime JPG data:

//  	/9j/4AAQSkZJRgABAgEASABIAAD/7Q18UGhvdG9zaG9wIDMuMAA4QklNA+0AAAAAABAASAAAAAEA
//  	AQBIAAAAAQABOEJJTQPzAAAAAAAIAAAAAAAAAAE4QklNBAoAAAAAAAEAADhCSU0nEAAAAAAACgAB
//  	AAAAAAAAAAI4QklNA/UAAAAAAEgAL2ZmAAEAbGZmAAYAAAAAAAEAL2ZmAAEAoZmaAAYAAAAAAAEA
//  	MgAAAAEAWgAAAAYAAAAAAAEANQAAAAEALQAAAAYAAAAAAAE4QklNBBQAAAAAAAQAAAABOEJJTQQM
//  	...

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

//  Specify the encryption to be used.
//  First we'll do AES-128 CBC
crypt.CryptAlgorithm = @"aes";
crypt.CipherMode = @"cbc";
crypt.KeyLength = [NSNumber numberWithInt:128];

NSString *ivHex = @"000102030405060708090A0B0C0D0E0F";
[crypt SetEncodedIV: ivHex encoding: @"hex"];

NSString *keyHex = @"000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F";
[crypt SetEncodedKey: keyHex encoding: @"hex"];

//  Do the in-place 128-bit AES CBC encryption.
//  The contents of jpgBytes are replaced with the encrypted bytes.
success = [crypt EncryptBd: jpgBytes];
if (success != YES) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

//  Examine the JPG bytes again.  The bytes should be different because they are encrypted:
NSLog(@"%@",[jpgBytes GetEncoded: @"base64_mime"]);

//  Sample base64_mime encrypted JPG data:

//  	sbz0babt1WCkQf5xKMdg/baZAcUBO5GVUUDF2BjVqmd+HrqKN+t6hAcqakL/bdo0q9hYmow0Tp1e
//  	AQ9V9DOiifQUZqWVkR+kL/c45bq8JGFDvgNl0djPt+yYhV789IB/fPH0upx+/ad++WNOlv1IxGMr
//  	Y1x1oERU/IsiEzafUJdI4kZ6FQo2IPGMF/Rm1h79I7hP1yYUFxvJyz+PzaySAUH1nLsNHyDVY5VY
//  	O90aH3steRSYbz8C8UF9wQ3qqEIXQNnnixvoNDnmHyY39VoVBI5F6rnPwYDfAk2t8tmuryFqvwAu
//  	...

//  Decrypt to restore back to the original:
success = [crypt DecryptBd: jpgBytes];
if (success != YES) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

NSLog(@"%@",[jpgBytes GetEncoded: @"base64_mime"]);

//  	/9j/4AAQSkZJRgABAgEASABIAAD/7Q18UGhvdG9zaG9wIDMuMAA4QklNA+0AAAAAABAASAAAAAEA
//  	AQBIAAAAAQABOEJJTQPzAAAAAAAIAAAAAAAAAAE4QklNBAoAAAAAAAEAADhCSU0nEAAAAAAACgAB
//  	AAAAAAAAAAI4QklNA/UAAAAAAEgAL2ZmAAEAbGZmAAYAAAAAAAEAL2ZmAAEAoZmaAAYAAAAAAAEA
//  	MgAAAAEAWgAAAAYAAAAAAAEANQAAAAEALQAAAAYAAAAAAAE4QklNBBQAAAAAAAQAAAABOEJJTQQM
//  	...

//  ----------------------------------------------------------------------------------
//  To do chacha20 encryption, just change the settings:

crypt.CryptAlgorithm = @"chacha20";
crypt.KeyLength = [NSNumber numberWithInt:256];
//  The initial count is the initial block counter for the chacha20 algorithm.
//  It can be any integer, but must be set to the same when decrypting.
crypt.InitialCount = [NSNumber numberWithInt:22];

success = [crypt EncryptBd: jpgBytes];
//  jpgBytes now contains chacha20 encrypted bytes.

success = [crypt DecryptBd: jpgBytes];
//  jpgBytes is now restored back to the original unencrypted by bytes.

//  Save the bytes to a file..
success = [jpgBytes WriteFile: @"qa_output/starfish.jpg"];

NSLog(@"%@",@"Success.");