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AES 128 Encryption

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gistfile1.m
Objective-C
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//
// NSData+AES.m
// AESTest
//
// Created by Oliver Drobnik on 19.12.12.
// Copyright (c) 2012 Oliver Drobnik. All rights reserved.
//
 
#import "NSData+AES.h"
 
#import <CommonCrypto/CommonCryptor.h>
 
@implementation NSData (AES)
 
- (NSData *)AES128EncryptWithKey:(NSString*)key {
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES128 + 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 = [self 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 numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
keyPtr, kCCKeySizeAES256,
NULL /* initialization vector (optional) */,
[self 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;
}
 
- (NSString *)hexString
{
NSMutableString *tmpString = [NSMutableString string];
const char *p = [self bytes];
for (int i=0; i<[self length]; i++)
{
[tmpString appendFormat:@"%02x", (unsigned char)p[i]];
}
return [tmpString uppercaseString];
}
 
@end

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