[democra]

Wouldn't radomized pixelation without using the actual textual data in the background be enough?

A tool where you can choose the background color and the text color. The pixalation tool then overlays the blur effect with random characters.

[can16358p]

That should work, given than the result doesn't have any actual input from the original data (except width of the text) and completely opaque over the actual text.

[rikschennink]

I imagine that would be the same as a black fill, just in a different color with noise.

I've used the original image data as a fill, but scaled down, so you get a mosaic effect. Then I randomise the tiles in that mosaic and then I blur. The result is that it seems like the original data was redacted but in reality the original data has been scrambled to such an extent that it can no longer be retrieved.