(Objective-C) ARC4 Encryption (ARCFOUR)

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

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#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);