Question

Is it possible to calculate sha256 hashes in the browser using the user’s video card, eg. by using WebGL or Flash?

I’m afraid this is all there is to ask, but if more elaboration is needed please do not hesitate to tell me in a comment.

Thanks.

Answer 1

This should be possible. Given an implementation of SHA as a fragment shader, you should be able to read back the results using readPixels:

Read Back Pixels [5.13.12] Pixels in
the current framebuffer can be read
back into an ArrayBufferView object.

void readPixels(int x, int y, long
width, long height, enum format, enum
type, Object pixels)

format: RGBA

type: UNSIGNED_BYTE

From the Kronos WebGL reference card (PDF)

For extra credit, do it all in an offscreen framebuffer, as described here.