Particle texture that has alpha in rgb channels

I’m trying to use particles with the alpha as the rgb channels in my program. Ranging from black (0,0,0) for transparent, to white (1,1,1) for opaque. Can I do this with a blend function or do I need to use a shader?

See glBlendFunc. Specifically, the SRC_COLOR blend functions. You can play with this here:

That said you could also write a shader, populate alpha and then use that to do your blending.