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//
// ViewController.m
// RC4Test
//
// Created by lv wei on 13-4-22.
// Copyright (c) 2013年 lv wei. All rights reserved.
//
#import "ViewController.h"
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonCryptor.h>
#import <CommonCrypto/CommonHMAC.h>
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSString* key = @"my little pang bao!";
NSString* content = @"五一回家休息几天啊，好好出去转转玩玩!";
NSData* initData = [content dataUsingEncoding:NSUTF8StringEncoding];
NSData* encryptData = [self RC4Encrypt:initData withKey:key];
printf("encryptData = %s\n",[encryptData description].UTF8String);
NSData* decryptData = [self RC4Decrypt:encryptData withKey:key];
NSString* utf8String = [[NSString alloc] initWithData:decryptData encoding:NSUTF8StringEncoding];
NSLog(@"decryptData = %@",utf8String);
[utf8String release];
}
- (NSData *)RC4Encrypt:(NSData*)srcData withKey:(NSString *)key {
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeMaxRC4+1]; // room for terminator (unused)
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [srcData length];
//See the doc: For block ciphers, the output size will always be less than or
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCKeySizeMaxRC4;
void *buffer = malloc(bufferSize);
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmRC4, kCCOptionPKCS7Padding|kCCOptionECBMode,
keyPtr, kCCKeySizeMaxRC4,
NULL /* initialization vector (optional) */,
[srcData bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free(buffer); //free the buffer;
return nil;
}
- (NSData *)RC4Decrypt:(NSData*)srcData withKey:(NSString *)key {
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeMaxRC4+1]; // room for terminator (unused)
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [srcData length];
//See the doc: For block ciphers, the output size will always be less than or
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmRC4, kCCOptionPKCS7Padding|kCCOptionECBMode,
keyPtr, kCCKeySizeMaxRC4,
NULL /* initialization vector (optional) */,
[srcData bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer); //free the buffer;
return nil;
}
@end
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