Link encryption

Link encryption is an approach to communications security that encrypts and decrypts all traffic at each end of a communications line (e.g. a teleprinter circuit or the line between two network switches). It contrasts with end-to-end encryption where messages are encrypted by the sender at the point of origin and only decrypted by the intended receiver. Link encryption offers a couple of advantages:

• encryption is automatic so there is less opportunity for human error.
• if the communications link operates continuously and carries an unvarying level of traffic, link encryption defeats traffic analysis.

On the other hand, end-to-end encryption ensures only authorized persons see the plaintext.

Link encryption can be used with end-to-end systems by superencrypting the messages.

Bulk encryption refers to encrypting a large number of circuits at once, after they have been multiplexed.