You may very well have read about the latest leak supposedly sourced from the secret data stolen by whistleblower Edward Snowden.
The three-bullet version tells approximately this story:
- Intelligence services managed to penetrate the network of a major SIM card manufacturer.
- They got hold of large amounts of cryptographic key material.
- They can therefore eavesdrop millions, perhaps even billions, of mobile devices.
Actually, there’s a subtle rider to the last item.
Having copies of the keys in the story doesn’t just let you listen in to present and future calls, but theoretically to decrypt old calls, too.