Hello friends,
I'm going to share AES Encryption and Decryption Method for Securely sending your data over the web. Please check the below code :
Step 1: First you have to include these two files into your project.
#include <CommonCrypto/CommonCryptor.h>
@interface NSData(AES)
- (NSData*)AES128Decrypt;
- (NSData*)AES128Encrypt;
@end
#import "NSData+AES.h"
NSString *iv = @"fedcba9876543210";
NSString *key = @"0123456789abcdef";
@implementation NSData (AES)
-(NSData*)AES128Encrypt
{
char ivPtr[kCCKeySizeAES128 + 1];
bzero(ivPtr, sizeof(ivPtr));
// fetch iv data
[iv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];
// '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, 0,
keyPtr, kCCKeySizeAES128,
ivPtr/* 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;
}
- (NSData*)AES128Decrypt
{
char ivPtr[kCCKeySizeAES128 + 1];
bzero(ivPtr, sizeof(ivPtr));
// fetch iv data
[iv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];
// '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 numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, 0,
keyPtr, kCCKeySizeAES128,
ivPtr /* initialization vector (optional) */,
[self 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 dataWithBytes:buffer length:numBytesDecrypted] ;
}
free(buffer); //free the buffer;
return nil;
}
@end
Step 2: You have to import "Security.framework" into your project.
Step 3: Now, you need to put below code into the class where you want to Encrypt or Decrypt a string and also need to import "NSData+AES.h" file.
- (void)testActuallyEncrypting:(NSString *)hexString
{
NSLog(@"Encrypted HexString : %@",hexString);
NSData *data = [self dataFromHexString:hexString];
NSData *encryptedData = [NSData dataWithBytes:[data bytes] length:[data length]];
NSData *decryptedData = [encryptedData AES128Decrypt];
NSString *decryptedString = [NSString stringWithUTF8String:[decryptedData bytes]];
NSLog(@"Decrypted String : %@",decryptedString);
decryptedString = [self addPaddingToString:decryptedString];
decryptedData = [NSData dataWithBytes:[decryptedString UTF8String] length:[[decryptedString dataUsingEncoding:NSUTF8StringEncoding] length]];
encryptedData = [decryptedData AES128Encrypt];
if (encryptedData!=nil)
{
NSString *encryptedHexString = [self hexStringFromData:encryptedData];
NSLog(@"Encrypted HexString : %@",encryptedHexString);
// NSData *data1 = [self dataFromHexString:encryptedHexString];
// NSData *encryptedData1 = [NSData dataWithBytes:[data1 bytes] length:[data1 length]];
// NSData *decryptedData1 = [encryptedData1 AES128Decrypt];
// NSString *decryptedString1 = [NSString stringWithUTF8String:[decryptedData1 bytes]];
// NSLog(@"Decrypted String Testing 123: %@",[decryptedString1 stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@" "]]);
}
}
Step 4 : For step3 , you have to add these three methods into your code.
// For Converting incoming HexString into NSData
- (NSData *)dataFromHexString:(NSString *)string
{
NSMutableData *stringData = [[[NSMutableData alloc] init] autorelease];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i;
for (i=0; i < [string length] / 2; i++) {
byte_chars[0] = [string characterAtIndex:i*2];
byte_chars[1] = [string characterAtIndex:i*2+1];
whole_byte = strtol(byte_chars, NULL, 16);
[stringData appendBytes:&whole_byte length:1];
}
return stringData;
}
// For converting Encrypted Data into NSString after the encryption
- (NSString*)hexStringFromData:(NSData *)data
{
unichar* hexChars = (unichar*)malloc(sizeof(unichar) * (data.length*2));
unsigned char* bytes = (unsigned char*)data.bytes;
for (NSUInteger i = 0; i < data.length; i++) {
unichar c = bytes[i] / 16;
if (c < 10) c += '0';
else c += 'a' - 10;
hexChars[i*2] = c;
c = bytes[i] % 16;
if (c < 10) c += '0';
else c += 'a' - 10;
hexChars[i*2+1] = c;
}
NSString* retVal = [[NSString alloc] initWithCharactersNoCopy:hexChars
length:data.length*2
freeWhenDone:YES];
return [retVal autorelease];
}
// For padding into a string for required string length
-(NSString *)addPaddingToString:(NSString *)string
{
NSInteger size = 16;
NSInteger x = [string length]%size;
NSInteger padLength = size - x;
for (int i=0; i<padLength; i++)
{
string = [string stringByAppendingString:@" "];
}
return string;
}
By following all above steps, you will be able to Implement AES Encryption and Decryption. If any one has query then place you it over here.
Thanks and Regards,
Nilesh Prajapati
