US Patent 8635441 Encryption-based control of network traffic

A computer-implemented method for protecting a computer network (22) includes receiving at a gateway (24) data transmitted from a source address for delivery to a destination on the computer network. The data are encrypted at the gateway using an encryption key selected from a set of one or more keys that are not available to the source address. The encrypted data are transmitted over the computer network toward the destination. The transmitted encrypted data are received and decrypted for use at the destination by means of one of the keys in the set.