I'm using RNCryptor to crypt files and for large files I use NSInputStream to separate file into chunks and to encode / decode those chunks. It worked great until I needed to base64 encode / decode chunks which are passed to streams.
Following code works perfectly fine for encoding, except it doesn't do base64 encoding:
NSInputStream *tmpStream = [[NSInputStream alloc] initWithURL:fileURL];
NSOutputStream *outputStream = [NSOutputStream outputStreamToFileAtPath:filePath append:NO];
[tmpStream open];
[outputStream open];
__block NSMutableData *data = [NSMutableData dataWithLength:kBlockSize];
__block RNEncryptor *encryptor = nil;
dispatch_block_t readStreamBlock = ^{
[data setLength:kBlockSize];
NSInteger bytesRead = [tmpStream read:[data mutableBytes] maxLength:kBlockSize];
if (bytesRead < 0) {
NSLog(@"An error occurred while decrypting file stream");
if (resultBlock) { resultBlock(nil); }
return;
}
else if (bytesRead == 0){
[encryptor finish];
}
else {
[data setLength:bytesRead];
[encryptor addData:data];
}
};
encryptor = [[RNEncryptor alloc] initWithSettings:kRNCryptorAES256Settings
password:HUCryptorPassword
handler:^(RNCryptor *cryptor, NSData *data) {
[outputStream write:data.bytes maxLength:data.length];
if(cryptor.isFinished){
[outputStream close];
if (resultBlock) {
resultBlock([NSString stringWithFormat:@"%@", filePath]);
}
}
else {
readStreamBlock();
}
}];
readStreamBlock();
I tried adding base64 encoding after the data is encrypted and before writing to output stream:
NSData *base64Data = [data base64EncodedDataWithOptions:kNilOptions]; //Tried with all options
[outputStream write:base64Data.bytes maxLength:base64Data.length];
But that gives me incorrect results in output file.
Only correct way I get correctly encoded / decoded data is to load whole file in memory and call encode / decode methods.
NSData *resultData = [NSData dataWithContentsOfFile:filePath]; //This is location of output file stream
NSData *encodedData = [resultData base64EncodedDataWithOptions:kNilOptions]; //Gives me correct base64 encoded data
I want to avoid that since I need to make encoding / decoding big files, such as videos, sounds and images.
Is there any safe way to accomplish this?
