Audio Encryption/Decryption iOS

[Tristan Freeman]

I'm new to encryption and I'm currently using RNCryptor to encrypt and decrypt audio recordings. The encryption is correct since the first few bytes are 0x301(which is what I want) but the decrypted NSData is causing the AVAudio Player to fail init. I'm not sure if the way that I'm handling the encryption is causing a conversion from an audio format but any help would be appreciated. The code I'm using to encrypt and decrypt is below.

- (void)renameFileInDocumentsFolder:(NSString *)oldFilename withNewName:(NSString *)newFilename

{

    

    NSFileManager *filemgr;

    

    NSString *oldPath = [self getFilePathFromDocumentsFolder:oldFilename];

    filemgr = [NSFileManager defaultManager];

    NSData *data = [filemgr contentsAtPath:oldPath];

    

     NSString *destPath = [[oldPath stringByDeletingLastPathComponent] stringByAppendingPathComponent:[newFilename stringByAppendingString:@".m4a"]];

    NSLog(@"DEST:%@", destPath);

    NSError *error;

    NSData *encryptedData = [RNEncryptor encryptData:data

                                        withSettings:kRNCryptorAES256Settings

                                            password:@"ABC123"

                                               error:&error];

    

    

    

    [encryptedData writeToFile:destPath atomically:YES];

    [filemgr removeItemAtPath:oldPath error:&error];

    

}

-(NSData *)decryptFilePathFromDocumentsFolder:(NSString *)filename

{

    AudioRecorderAppDelegate *appDelegate=[AudioRecorderAppDelegate sharedDelegate];

    _cacheDirectory = [[[appDelegate applicationCacheDirectory]path]stringByAppendingPathComponent:@"Recordings"];

   // NSFileManager *fileManager = [NSFileManager defaultManager];

    NSError *error;

    

    NSString *filePath = [_cacheDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.m4a", filename]];

    NSData *data = [NSData dataWithContentsOfFile:filePath];

   // NSData *encData = [fileManager contentsAtPath:filePath];

    //NSData *encData = [NSData dataWithContentsOfFile:filePath];

    NSData *decData = [RNDecryptor decryptData:data withPassword:@"ABC123" error:&error];

    

    

    

    return decData;

}

[Rob Napier]

You're not checking any of the errors. What error does the encryptor and decryptor return, if any?

Rob

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[Tristan Freeman]

The encryptor and decrypt don't return any errors but I do get the OSStatus error for kAudioFileInvalidFileError.

Error: The operation couldn’t be completed. (OSStatus error 1685348671.)

[Rob Napier]

If there isn't any error decrypting than you probably aren't encrypting what you think you are. Check the output bytes and make sure it works with no encryption.

Rob

[Tristan Freeman]

Thank you for the help! You were right, I wasn't encrypting what I thought I was but I got it figured out and working.