AES encryption / decryption Objective-C category

NSData+NSData_AES.h

//
//  NSData+NSData_AES.h
//  CSVContactDemo
//
//  Created by Michael on 14-7-23.
//  Copyright (c) 2014年 Michael. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSData (Encryption)

- (NSData *)AES256EncryptWithKey:(NSString *)key;   //加密
- (NSData *)AES256DecryptWithKey:(NSString *)key;   //解密

@end

NSData+NSData_AES.m

//
//  NSData+NSData_AES.m
//  CSVContactDemo
//
//  Created by Michael on 14-7-23.
//  Copyright (c) 2014年 Michael. All rights reserved.
//


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

@implementation NSData (Encryption)

- (NSData *)AES256EncryptWithKey:(NSString *)key {//加密
    char keyPtr[kCCKeySizeAES256+1];
    bzero(keyPtr, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    NSUInteger dataLength = [self length];
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding | kCCOptionECBMode,
                                          keyPtr, kCCBlockSizeAES128,
                                          NULL,
                                          [self bytes], dataLength,
                                          buffer, bufferSize,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }
    free(buffer);
    return nil;
}


- (NSData *)AES256DecryptWithKey:(NSString *)key {//解密
    char keyPtr[kCCKeySizeAES256+1];
    bzero(keyPtr, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    NSUInteger dataLength = [self length];
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    size_t numBytesDecrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding | kCCOptionECBMode,
                                          keyPtr, kCCBlockSizeAES128,
                                          NULL,
                                          [self bytes], dataLength,
                                          buffer, bufferSize,
                                          &numBytesDecrypted);
    if (cryptStatus == kCCSuccess) {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
    }
    free(buffer);
    return nil;
}

@end