<i>Searching for &quot;expand 32-byte k&quot; would directly lead you to Salsa. The exact code used in the malware can be found here. I am using the word exact in a broad sense. If it had been a ditto copy, we would have no chance of breaking it. The original Salsa implementation uses 32 bit (uint32_t) variables. This salsa implementation uses 16 bit variables for the same purpose borking it badly.</i><p>:)<p>The author made it look so easy to reverse this.  Kudos, and thanks for the community service.