I am fine with stipulating that Javascript cryptography is approximately as good as rot13, and so we can move on.
The one thing I can say about the JS cryptography is that it normally protects somewhat against passive sniffing attacks, but when it's as broken as this, it doesn't even accomplish that task.
This sort of thing seems chronic in the industry, and it's dismaying.
Management made the decision that my trivial change to eliminate replay attacks was "too much effort". I am inclined to agree, since even with such a change the effort required to circumvent their entire so-called security is minimal.
Next quarter they're introducing e-commerce solutions. Dear god.