Triple DES encryption example using the CommonCrypto Library

gistfile1.m

#import <CommonCrypto/CommonCryptor.h>

#warning ADD Security.framework to your project

+ (NSData *)tripleDesEncryptData:(NSData *)inputData
                             key:(NSData *)keyData
                           error:(NSError **)error
{
  NSParameterAssert(inputData);
  NSParameterAssert(keyData);

  size_t outLength;

  NSAssert(keyData.length == kCCKeySize3DES, @"the keyData is an invalid size");
  
  NSMutableData *outputData = [NSMutableData dataWithLength:(inputData.length  +  kCCBlockSize3DES)];
  
  CCCryptorStatus
  result = CCCrypt(kCCEncrypt, // operation
                   kCCAlgorithm3DES, // Algorithm
                   0, // options
                   keyData.bytes, // key
                   keyData.length, // keylength
                   nil,// iv
                   inputData.bytes, // dataIn
                   inputData.length, // dataInLength,
                   outputData.mutableBytes, // dataOut
                   outputData.length, // dataOutAvailable
                   &outLength); // dataOutMoved

  if (result != kCCSuccess) {
    if (error != NULL) {
      *error = [NSError errorWithDomain:@"com.your_domain.your_project_name.your_class_name."
                                   code:result
                               userInfo:nil];
    }
    return nil;
  }
  [outputData setLength:outLength];
  return outputData;
}

Notice that the Initialization Vector (iv) is nil in this example.

Notice that I'm passing zero for "options" parameter for the CCCrypt method. You could specify kCCOptionPKCS7Padding or kCCOptionECBMode instead. Look in CommonCryptor.h for details.

to decrypt just change kCCEncrypt to kCCDecrypt

From where I can get CommonCrypto File