Product cipher, data encryption scheme in which the ciphertext produced by encrypting a plaintext document is subjected to further encryption.
Since then, each issue of Inspire has offered a how-to section on encrypting communications, recommending MS2 as the main encryption tool.
To decrypt the resulting ciphertext it is necessary to have an inverse combiner function or for the original encryption function to be involutory i.e., the encryption and decryption functions are identical, so that encrypting the ciphertext restores the plaintext.
"Also, some customers were confused by us initially making BT Sport available free to air on BT TV and then encrypting the channel".
That is why a number of technology companies, including Microsoft, Yahoo and Google, are now encrypting far more of the data that flow across their networks, and between themselves and their customers.Educating employees about security risks is equally important.
This ensures that encrypting data, which relies on multiplying primes, is easy.
In the aftermath of Mr Snowden's earlier revelations about snooping on e-mails, many of the web's big companies said they would move towards encrypting their data.
Java, which is object-oriented, now comes in a pint-size version that fits on a "smart card", a credit card with a chip embedded into it for encrypting data in mobile phones and other portable devices.Another advantage of object-oriented programming is that groups of users (eg, retailers, estate agents, doctors) can create and share new classes of object.
Many legitimate apps transmit their data without encrypting it first, allowing anyone so inclined to pluck it from the air and read it.Consumers have learned the hard way that their PCs are vulnerable, but that realisation has not yet sunk in for their phones.
But, as Mr Derbyshire shows, algebra today is an essential part of the wider mathematical landscape, with a huge range of applications from encrypting communications to the construction of computer chips.
