Objective-C code for encrypt and decrypt by AES-128 encryption.

NSData+AES.h

/**
 http://mythosil.hatenablog.com/entry/20111017/1318873155
 http://blog.dealforest.net/2012/03/ios-android-per-aes-crypt-connection/
 */

@interface NSData (AES)

- (NSData *)AES128EncryptedDataWithKey:(NSString *)key;
- (NSData *)AES128DecryptedDataWithKey:(NSString *)key;
- (NSData *)AES128EncryptedDataWithKey:(NSString *)key iv:(NSString *)iv;
- (NSData *)AES128DecryptedDataWithKey:(NSString *)key iv:(NSString *)iv;

@end

NSData+AES.m

#import "NSData+AES.h"
#import <CommonCrypto/CommonCryptor.h>

@implementation NSData (AES)

- (NSData *)AES128EncryptedDataWithKey:(NSString *)key
{
    return [self AES128EncryptedDataWithKey:key iv:nil];
}

- (NSData *)AES128DecryptedDataWithKey:(NSString *)key
{
    return [self AES128DecryptedDataWithKey:key iv:nil];
}

- (NSData *)AES128EncryptedDataWithKey:(NSString *)key iv:(NSString *)iv
{
    return [self AES128Operation:kCCEncrypt key:key iv:iv];
}

- (NSData *)AES128DecryptedDataWithKey:(NSString *)key iv:(NSString *)iv
{
    return [self AES128Operation:kCCDecrypt key:key iv:iv];
}

- (NSData *)AES128Operation:(CCOperation)operation key:(NSString *)key iv:(NSString *)iv
{
    char keyPtr[kCCKeySizeAES128 + 1];
    bzero(keyPtr, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    char ivPtr[kCCBlockSizeAES128 + 1];
    bzero(ivPtr, sizeof(ivPtr));
    if (iv) {
        [iv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];
    }

    NSUInteger dataLength = [self length];
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);

    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(operation,
                                          kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding | kCCOptionECBMode,
                                          keyPtr,
                                          kCCBlockSizeAES128,
                                          ivPtr,
                                          [self bytes],
                                          dataLength,
                                          buffer,
                                          bufferSize,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }
    free(buffer);
    return nil;
}

@end

dataWithBytesNoCopy means the NSData object will take ownership of the memory location so you don't have to free it afterwards.

Please note that the AES-ECB mode of encryption used here is not secure in any way!
See here for details: http://crypto.stackexchange.com/questions/20941/why-shouldnt-i-use-ecb-encryption

It can be fixed by deleting the kCCOptionECBModekeyword in the CCCrypt(...) call. CCCrypt will then use CBC which is its default mode.

how to use

Add #import<UIKit/UiKit.h> in header file.

Hello after decryption it is giving null
here the data is decrypted
theJson = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&theJsonError];
NSLog(@"RESPONSE_JSON :: %@",(NSString *)theJson);
LOGS : RESPONSE_JSON :: null

Any chance you can make this available to the rest of us? Apache / MIT license? By default this is copyrighted.

Abhishek9634 have you solved the issue am facing similar can you help me