(Objective-C) PBES2 Password-Based Encryption (PBE)

Demonstrates how to implement password-based encryption according to the PKCS #5 v2.0: Password-Based Cryptography Standard (published by RSA Laboratories). This example uses PBES2, which ise based on the PBKDF2 function and an underlying block cipher such as RC2, DES, etc.

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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 properties for PBES2 encryption:

crypt.CryptAlgorithm = @"pbes2";
crypt.PbesPassword = @"mySecretPassword";

// Set the underlying PBE algorithm (and key length):
crypt.PbesAlgorithm = @"rc2";
crypt.KeyLength = [NSNumber numberWithInt:128];
// Only required for the RC2 algorithm:
crypt.Rc2EffectiveKeyLength = [NSNumber numberWithInt:128];

// By definition, the block encryption algorithm (RC2 or whichever
// was selected) will run in CBC mode.  Therefore, we need
// an IV.  The IV is equal in length to the block size of the
// algorithm.  RC2 has a block size of 8 bytes (regardless of
// key length), so set the IV to some value that is 8 bytes 
// in length:
[crypt SetEncodedIV: @"0000000000000000" encoding: @"hex"];

// Give it some salt:
[crypt SetEncodedSalt: @"0102030405060708" encoding: @"hex"];

// A higher iteration count makes the algorithm more
// computationally expensive and therefore exhaustive
// searches (for breaking the encryption) is more difficult:
crypt.IterationCount = [NSNumber numberWithInt:1024];

// A hash algorithm needs to be set for PBES2:
crypt.HashAlgorithm = @"sha1";

// Indicate that the encrypted bytes should be returned
// as a hex string:
crypt.EncodingMode = @"hex";

NSString *plainText = @"To be encrypted.";

NSString *encryptedText = [crypt EncryptStringENC: plainText];

NSLog(@"%@",encryptedText);

// Now decrypt:
NSString *decryptedText = [crypt DecryptStringENC: encryptedText];

NSLog(@"%@",decryptedText);