File Encryption and Decryption using AES in Objective-C - ios

Question

I am very new in iOS app developing. I need to encrypt and decrypt the files in ios using objective-c. While i am searching i got string encrypt and decrypt only.
CCCryptorStatus status = CCCrypt(kCCDecrypt,/* kCCEncrypt, etc. */
kCCAlgorithmAES128, /* kCCAlgorithmAES128, etc. */
kCCOptionPKCS7Padding, /* kCCOptionPKCS7Padding, etc. */
keyPointer, kCCKeySizeAES256,/* key and its length */
ivPointer, /* initialization vector - use same IV which was used for decryption */
[encryptedText bytes], [encryptedText length], //input
buff, buffSize,//output
&numBytesEncrypted);
Here how can i encrypt and decrypt the files. Thanks

Answer 1

Finally i got the solution for file encrypt and decrypt using AES. I maintain same code for both encrypt and decrypt for files using crypt type. if we pass the crypttype as 1 the file encrypt using aes. If we do decrypt we can pass the value as 2.
FileAes.m
RCT_EXPORT_METHOD(encryptDecryptFile:(NSString *)crypType
appkey:(NSString *)key
inputPath:(NSString *)inputPath
outPutPath : (NSString *)outputPath
resolver:(RCTPromiseResolveBlock)resolve
rejecter:(RCTPromiseRejectBlock)reject)
{
if ([[SecurityUtil encryptDecryptAESFile:crypType app_key:key input_path:inputPath output_path:outputPath] length] <= 0) {
reject(#"ERROR", #"decrypt failed", nil);
}
resolve ([SecurityUtil encryptDecryptAESFile:crypType app_key:key input_path:inputPath output_path:outputPath]);
}
SecurityUtil.m
+(NSString*)encryptDecryptAESFile:(NSString*)cryptType app_key:(NSString*)key input_path:(NSString*)inputPath output_path:(NSString *)outputPath
{
NSLog(#"file input path===> %#",cryptType);
NSString *res;
NSData *decryedData;
#try {
NSData *data = [NSData dataWithContentsOfFile:inputPath];
if(cryptType == #"1"){
decryedData = [data AES128EncryptFileWithKey:key ];
}else{
decryedData = [data AES128DecryptFileWithKey:key ];
}
//NSData *decryedData = [data AES128DecryptFileWithKey:key gIv:key];
[decryedData writeToFile:outputPath atomically:YES];
res =#"success";
return res;
}
#catch (NSException *exception) {
NSLog(#"Exception in decrypt File==> %#", exception.reason);
res=#"failure";
return res;
}
#finally {
NSLog(#"Finally condition=== %#",res);
return res;
}
}
NSDataAesFile.m
- (NSData *)AES128DecryptFileWithKey:(NSString *)key {//FileDecrypt
char keyPtr[kCCKeySizeAES128+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
char ivPtr[kCCKeySizeAES128+1];
memset(ivPtr, 0, sizeof(ivPtr));
[key getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];//gIv
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
kCCAlgorithmAES128,
kCCOptionPKCS7Padding,
keyPtr,
kCCBlockSizeAES128,
ivPtr,
[self bytes],
dataLength,
buffer,
bufferSize,
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
NSLog(#"crypt status==> %d", cryptStatus);
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer);
return nil;
}
The above code is working for me. May be it will help.