If Eve intercepts Bob's pulses and changes the separation between them, she can trick Alice into sending photons that have slightly different polarisations from those that were intended.

ECONOMIST: Secure cryptography is only as safe as its weakest link

The court was also expected to rule on the admissibility of the captain's phone intercepts at the police station following his detention right after the shipwreck.

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Some experts reckon the law on intercepts would not make listening to someone's messages after that person had heard them an offence, distasteful as it might seem.

ECONOMIST: The furore over phone-hacking

They spoke on the same day a U.S. official first told CNN that communications intercepts indicated North Korea may be planning to launch a mobile ballistic missile in the coming days or weeks.

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Arrow 3 detects an incoming missile, intercepts it and destroys it with a second missile above the earth's atmosphere.

BBC: Israel successfully tests Arrow 3 missile interceptor

Now, whether or not that's the case with the NSA program depends entirely on what the facts of the intercepts of the communications are.

NPR: Invoking the State Secrets Privilege

Investigations by Britain's domestic security service, MI5, can include undercover surveillance, phone tapping and communications intercepts.

NPR: UK Soldier Slaying Suspects Had Been Investigated