在iOS上使用RNCryptor异步解密大文件 [英] Asynchronously decrypt a large file with RNCryptor on iOS

问题描述

我需要使用iOS上的RNCryptor异步解密大文件（以便显示一个进度条）。我没有发现任何地方的例子，因此尝试了我猜到的是正确的，但是...我所想出来的不起作用：解密器的处理程序从不被调用，并且线程在发送所有数据后与EXC_BAD_ADDRESS崩溃在函数结束时。

  NSOutputStream * decryptptedStream = [NSOutputStream outputStreamToFileAtPath：decryptptedPath append：NO]; 
 [decryptptedStream open]; 
 
 NSUInteger totalBytesToRead = [[[NSFileManager defaultManager] attributesOfItemAtPath：tempPath error：nil] fileSize]; 
 __block NSUInteger totalBytesRead = 0; 
 
 LOG（我有％d个字节来解密，totalBytesToRead）; 
 
 RNDecryptor * decryptor = [[RNDecryptor alloc] initWithPassword：SNCatalogPassword处理程序：^（RNCryptor * cryptor，NSData * data）{
 totalBytesRead + = data.length; 
 [decryptptedStream write：data.bytes maxLength：data.length]; 
 
 LOG（Decrypted％d bytes：％d /％d bytes treated，data.length，totalBytesRead，totalBytesToRead）; 
 
 if（cryptor.isFinished）
 {
 //继续
 LOG（完成解密）; 
 
 [decryptptedStream close]; 
 
} 
}]; 
 
 //将数据提供给解密器
 NSInputStream * cryptedStream = [NSInputStream inputStreamWithFileAtPath：tempPath]; 
 [cryptedStream open]; 
 while（cryptedStream.hasBytesAvailable）
 {
 uint8_t buf [4096]; 
 NSUInteger bytesRead = [cryptedStream read：buf maxLength：4096]; 
 NSData * data = [NSData dataWithBytes：buf length：bytesRead]; 
 LOG（发送％d字节到解密...，bytesRead）; 
 
 dispatch_async（dispatch_get_main_queue（），^ {
 [decryptor addData：data]; 
}）; 
} 
 
 LOG（发送所有东西）; 
 [decryptor finish]; 
 [cryptedStream close]; 
  

（Obvsiouly， tempPath 是加密的文件; decryptptedPath 是解密数据应写入的路径）。

另外我是新来的ARC，所以这可能是一个记忆或调度相关的问题。

感谢任何帮助。

解决方案

我今天遇到同样的问题，似乎是由于最近在iOS6中抛弃了dispatch_get_current_queue（）。

通过更改[RNCryptor initWithHandler：]创建一个新队列，解密工作正常。

  NSString * responseQueueName = [@net。 robnapier.response。 stringByAppendingString：NSStringFromClass（[self class]）]; 
 _responseQueue = dispatch_queue_create（[responseQueueName UTF8String]，NULL）; 
  

您可以在async_decrypt分支上找到修复程序和关联的单元测试（基于您的代码）我的分支在github上。

提交 csteynberg / RNCryptor

I need to asynchronously decrypt a large file with RNCryptor on iOS (so as to show a progress bar). I have found no example anywhere, and thus have tried what I guessed was right, but... what I've come up with doesn't work : the decryptor’s handler is never called, and the thread crashed with EXC_BAD_ADDRESS after sending all data at the end of the function.

NSOutputStream *decryptedStream = [NSOutputStream outputStreamToFileAtPath:decryptedPath append:NO];
[decryptedStream open];

NSUInteger totalBytesToRead = [[[NSFileManager defaultManager] attributesOfItemAtPath:tempPath error:nil] fileSize];
__block NSUInteger totalBytesRead = 0;

LOG("I've got %d bytes to decrypt.", totalBytesToRead);

RNDecryptor *decryptor = [[RNDecryptor alloc] initWithPassword:SNCatalogPassword handler:^(RNCryptor *cryptor, NSData *data) {
    totalBytesRead += data.length;
    [decryptedStream write:data.bytes maxLength:data.length];

    LOG("Decrypted %d bytes : %d / %d bytes treated", data.length, totalBytesRead, totalBytesToRead);

    if (cryptor.isFinished)
    {
        //proceed
        LOG("Done with decrypting.");

        [decryptedStream close];

    }
}];

// Feed data to the decryptor
NSInputStream *cryptedStream = [NSInputStream inputStreamWithFileAtPath:tempPath];
[cryptedStream open];
while (cryptedStream.hasBytesAvailable)
{
    uint8_t buf[4096];
    NSUInteger bytesRead = [cryptedStream read:buf maxLength:4096];
    NSData *data = [NSData dataWithBytes:buf length:bytesRead];
    LOG("Sending %d bytes to decryptor...", bytesRead);

    dispatch_async(dispatch_get_main_queue(), ^{
        [decryptor addData:data];
    });
}

LOG("Sent everything.");
[decryptor finish];
[cryptedStream close];

(Obvsiouly, tempPath is the path to the crypted file ; decryptedPath is the path where decrypted data should be written).

Also I'm new to ARC so this may be a memory- or dispatch-related problem.

Thanks for any help.

解决方案

I ran into the same issue today, and it seems to be happening due to the recent deprecation of dispatch_get_current_queue() in iOS6.

By changing [RNCryptor initWithHandler:] to create a new queue the decryption works correctly.

NSString *responseQueueName = [@"net.robnapier.response." stringByAppendingString:NSStringFromClass([self class])];
_responseQueue = dispatch_queue_create([responseQueueName UTF8String], NULL);

You can find the fix and an associated unit test (based on your code) on the async_decrypt branch of my fork on github.

Commit on csteynberg/RNCryptor

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