Abstract: A system may include at least one hardware processor implementing a verification unit configured to: receive a set of data from a first computer network; transmit an encrypted version of the set of data to a destination within a second computer network; receive a signature associated with the set of data from the first computer network; verify that the signature is indicative of the set of data being from a known source; and in response to verification of the signature, transmit a decryption key associated with the encrypted version of the set of data to the destination, wherein the destination is configured to decrypt the set of data with the decryption key.

Abstract: A computer-implemented method of mitigating the effect of a security threat present in a computer file of a known type. The method involves modifying the file to mitigate unsafe behaviour when the file is interpreted in accordance with the known type and/or in accordance with one or more different file types, and subsequently checking the modified file to ensure that it exhibits a known safe behaviour when interpreted according to the one or more different file types. The modified file may be checked to ensure it exhibits known safe behaviour when interpreted according to the one or more different file types. There may be two or more independent checks each according to one of the one or more different file types. The independent checks may be done in parallel. The step of modifying may include adding a damper to the file.

Abstract: A first computer network 1, the computer network which is transmitting data, and a second computer network 2, the computer network which is receiving the data. The first computer network comprises a verification unit 7, which comprises a key generator 9, an encryption engine 10, a verification hasher 11, a signature verifier 12. The encryption engine 10 encrypts the data stream using an encryption key. As each part of the data stream is encrypted it is transmitted to the second computer network 2. The signature verifier 12 uses a decryption key to decrypt a signature for the set of data, and compares the decrypted signature to the hash value calculated by the verification hasher 11. The decrypted signature matching the hash value means the correct private key was used to create the signature and the set of data has not been modified since the signature was created, and so the signature is valid.

Abstract: A firewall system employs signature validation hardware communicating via low level communication protocols and with inner and outer host computers, which have network protocol stacks and for implementing complex communication protocols with remote source and destination computers. The source computer has data checker and signature functionalities, which respectively check data and generate digital signatures for data to be transmitted. The inner host computer receives transmitted data and converts it to a lower protocol level at which the hardware operates. The hardware uses digital circuitry for protocols and checking. It validates signatures in data at a software application level, but only requires protocols that are simple and low level. The firewall system communicates with the source and destination computers via high performance connection media.