Add Salsa20 and XSalsa20 operation

[joostrijneveld]

As a continuation of #1466 and #1606, this adds the Salsa20 and XSalsa20 stream ciphers, as well as parameters to support their round-reduced variants (Salsa20/8, Salsa20/12, XSalsa20/8, XSalsa20/12).

This relates to #1603 as well.

[a3957273]

Just tried it out and this seems like a fantastic implementation.

Whilst I'm not sure on some of the decisions here (e.g. including 'output format', when the 'to hex' operation exists), it does match the rest of the crypt operations that are implemented within CyberChef.

Thanks for the contribution ❤️ .

[joostrijneveld]

Thanks for merging!

Whilst I'm not sure on some of the decisions here (e.g. including 'output format', when the 'to hex' operation exists), it does match the rest of the crypt operations that are implemented within CyberChef.

@a3957273 I completely agree; the same goes for input formats to some extent, I suppose. While I was somewhat reluctant, I figured I'd try to be consistent with the existing modules. There's definitely something to be said for small, atomic operations. Should we create a separate issue to clean up output formats across the various (crypt) recipes?