Looking to encrypt/decrypt external wavs in my sampler


#1

I have looked around the forum and most threads just discuss which algorithms to use like XOR or RSA. But I need to know which method to override to intercept a file being loaded and decrypt it before it gets sent to the reader. I’m guessing it’s in the juce::File class since I’m loading my samples in like:

File* file = new File(note_resource);
ScopedPointer<AudioFormatReader> reader = audioFormatManager.createReaderFor(*file);

So I plan on making my own File class, I was wondering if anyone with experience with this or anything similar has any advice on which method I should override


#2

I would suggest to inherit an InputStream and OutputStream. You can give them to any AudioFormatReader, and you have all freedom, if you get your encrypted data from a File, a MemoryBlock, or anything, even from a GZIPDecompressorInputStream…

You need to implement only 5 methods:
virtual int64 getTotalLength ()
virtual bool isExhausted ()
virtual int read (void *destBuffer, int maxBytesToRead)
virtual int64 getPosition ()
virtual bool setPosition (int64 newPosition)

Looks like only the read is specific to your problem…


#3

I wrote that as a POC, using XOR it works already (rather obfuscation than cryptography, but saves the CPU, RSA for wavs on the fly is probably a bad idea).
It looks like:

What I realised, it would be great to use a SIMD instruction instead.

JUCE Team: is it simple to add XOR to the FloatVectorOperations?
Is it naive to think, it is just a copy/paste job for
FloatVectorOperations::multiply (dest, src, num); ?

Cheers!


#4

Well, it’s not too hard to add, but wouldn’t want to put it into Float VectorOperations as it’s an integer thing.

TBH in a simple loop like that I’d be amazed if the compiler didn’t already manage to vectorise it properly.


#5

Hah, true indeed… but starting a new class for that…?

I think so too, that the optimiser should do already a fairly good job. But to quote a wise guy: “Only believe what you measured yourself” :wink: