Objective-C

ARC4 Encryption (ARCFOUR)

See more Encryption Examples

ARC4 (ARCFOUR) encryption. The Chilkat encryption component supports the ARC4 streaming encryption algorithm. Objective-C

#import <CkoCrypt2.h>
#import <NSString.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 encryption algorithm = "arc4"	
crypt.CryptAlgorithm = @"arc4";

//  KeyLength may range from 1 byte to 256 bytes.
//  (i.e. 8 bits to 2048 bits)
//  ARC4 key sizes are typically in the range of 
//  40 to 128 bits.
//  The KeyLength property is specified in bits:
crypt.KeyLength = [NSNumber numberWithInt:128];

//  Note: The PaddingScheme and CipherMode properties
//  do not apply w/ ARC4.  ARC4 does not encrypt in blocks --
//  it is a streaming encryption algorithm. The number of output bytes
//  is exactly equal to the number of input bytes.

//  EncodingMode specifies the encoding of the output for
//  encryption, and the input for decryption.
//  It may be "hex", "url", "base64", or "quoted-printable".
crypt.EncodingMode = @"hex";

//  Note: ARC4 does not utilize initialization vectors.  IV's only
//  apply to block encryption algorithms.  

//  The secret key must equal the size of the key.
//  For 128-bit encryption, the binary secret key is 16 bytes.
NSString *keyHex = @"000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F";
[crypt SetEncodedKey: keyHex encoding: @"hex"];

//  Encrypt a string...
//  The output length is exactly equal to the input.  In this
//  example, the input string is 44 chars (ANSI bytes) so the
//  output is 44 bytes -- and when hex encoded results in an
//  88-char string (2 chars per byte for the hex encoding).
NSString *encStr = [crypt EncryptStringENC: @"The quick brown fox jumps over the lazy dog."];
NSLog(@"%@",encStr);

//  Now decrypt:
NSString *decStr = [crypt DecryptStringENC: encStr];
NSLog(@"%@",decStr);