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;
}