Cryptographic communication system

• US 5,812,671 A
• Filed: 07/17/1996
• Issued: 09/22/1998
• Est. Priority Date: 07/17/1996
• Status: Expired due to Term

• Current Assignee: Xante Corporation
• Original Assignee: Xante Corporation
• Inventors: Ross, Robert C. Jr.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): White, Carmen D.
• Application Number:
  US08/682,298
• Time in Patent Office: 797 Days
• Field of Search: 380/25, 380/30, 380/49, 380/21
• US Class Current: 713/153
• CPC Class Codes: H04L 63/0464 using hop-by-hop encryption, i.e. wherein an intermediate entity decrypts the information and re-encrypts it before forwarding it
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

In this system parties have network access to a network secure communications gateway which stores the current encryption/decryption algorithms and keys for parties registered with the network secure communications gateway. For party A to send an encrypted message to party B, party A encrypts the message using party A'"'"'s secret key and encryption algorithm, copies of which are stored at the network gateway Party A sends the encrypted message, addressed to party B, initially to the gateway. The gateway decrypts the message, using party A'"'"'s secret key and algorithm, and then encrypts the decrypted message using party B'"'"'s secret key and algorithm. Finally, the gateway forwards the re-encrypted message to party B, where B decodes it using B'"'"'s secret key and algorithm. The secure communications gateway periodically changes client keys (or algorithms and keys) to provide additional system security.

Claims

1. A cryptographic communication method for transmitting encrypted messages over a public network from a sending node to a receiving node, including the steps of:

storing at an encryption gateway node a respective different private sending node decryption key and a respective different private receiving node encryption key for each of a plurality of nodes connected to said network;

first encrypting at said sending node a data file using a private sending node encryption key;

transmitting said data file encrypted in the first encrypting step over said network to an encryption gateway node;

first decrypting said data file at said encryption gateway node using a private sending node decryption key corresponding to the private sending node encryption key used in the first encrypting step;

second encrypting at said encryption gateway said data file which has been decrypted in the first decrypting step using a private receiving node encryption key for said receiving node;

transmitting said data file encrypted in the second encrypting step over said network to said receiving node;

second decrypting said data file at said receiving node using a decryption key corresponding to the private receiving node encryption key used in the second encrypting step;

periodically selecting one of said plurality of nodes connected to said network, generating a new encryption/decryption key for said one of said plurality of nodes, encrypting said new encryption/decryption key with an encryption/decryption key previously used by said one of said plurality of nodes, transmitting said new encryption/decryption key to said selected one of said plurality of nodes, and storing said new encryption/decryption key at said encryption gateway node.

2. A cryptographic communication method as in claim 1 wherein the step of periodically selecting one of said plurality of nodes is a performed on a random basis.

3. A cryptographic communication method for transmitting encrypted messages over a public network from a sending node to a receiving node, including the steps of:

storing at an encryption gateway node a respective different private sending node decryption key and a respective different private receiving node encryption key for each of a plurality of nodes connected to said network;

first encrypting at said sending node a data file using a private sending node encryption key;

transmitting said data file encrypted in the first encrypting step over said network to an encryption gateway node;

first decrypting said data file at said encryption gateway node using a private sending node decryption key corresponding to the private sending node encryption key used in the first encrypting step;

second encrypting at said encryption gateway said data file which has been decrypted in the first decrypting step using a private receiving node encryption key for said receiving node;

transmitting said data file encrypted in the second encrypting step over said network to said receiving node;

second decrypting said data file at said receiving node using a decryption key corresponding to the private receiving node encryption key used in the second encrypting step;

periodically selecting one of said plurality of nodes connected to said network, generating a new encryption/decryption algorithm for said one of said plurality of nodes, encrypting said new encryption/decryption algorithm with an encryption/decryption algorithm previously used by said one of said plurality of nodes, transmitting said new encryption/decryption algorithm to said selected one of said plurality of nodes, and storing said new encryption/decryption algorithm at said encryption gateway node.

4. A cryptographic communication method as in claim 3 wherein the step of periodically selecting one of said plurality of nodes is a performed on a random basis.