Tag Archives: security service

Encryption with Pencil and Paper



1984Given that George Orwell was English, one might think the British would be all too aware of the dangers of a police state. Despite being one of the most surveilled countries in the world with one security camera for every eleven people, politicians in the UK have put forward plans to record the online activities of people in the UK and force companies like Google and Apple to break the encryption on gadgets and apps. It’s clear from both Snowden’s revelations and other sources that the UK’s security services have been routinely collecting large quantities of phone data with little legislative oversight.

As expected, the powers-that-be trot out the usual scaremongering tactics from terrorists to paedophiles, and while politicians aren’t known for their intelligence, the current proposals around encryption seem particularly stupid and at odds with experts in the fields of security and mathematics.

Encryption isn’t always that easy to understand, so this video shows a very simple but secure method for encrypting and decrypting messages using nothing more than paper and pencil. The process is a bit laborious but it illustrates how easy it is to be secure even without a computer and that any attempt to put a back door into digital encryption will only compromise the integrity of the internet for everyone.

The BBC’s “In Our Time” radio programme tackles “P v NP” this week and part of the discourse involves prime numbers and their role in encryption. It’s available as a podcast so it’s recommended listening too.

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