Insecure by design: protocols for encrypted phone calls
benthamsgaze.orgAn update on this story shows that GCHQ also tried to squash another key exchange algorithm (MIKEY-IBAKE) because it made surveillance too hard – and this was the motivation for MIKEY-SAKE http://www.theregister.co.uk/2016/01/21/mikey_ibake/
Related from 2 days ago: "GCHQ-built phone voice encryption has massive backdoor" https://news.ycombinator.com/item?id=10936914