Cryptation system for packet switching networks based on digital chaotic models

• US 6,792,111 B1
• Filed: 10/12/1999
• Issued: 09/14/2004
• Est. Priority Date: 10/12/1998
• Status: Expired due to Term

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Beritelli, Francesco, Italia, Francesco, Fortuna, Luigi, Di Cola, Eusebio
• Primary Examiner(s): Sheikh, Ayaz
• Assistant Examiner(s): Zand, Kambiz
• Application Number:
  US09/416,321
• Time in Patent Office: 1,799 Days
• Field of Search: 380/263, 380/206, 380/209, 380/257, 380/45, 713/160, 713/201
• US Class Current: 380/263
• CPC Class Codes: H04L 2209/04 Masking or blinding
• CPC Class Codes: H04L 2209/125 Parallelization or pipelining, e.g. for accelerating processing of cryptographic operations
• CPC Class Codes: H04L 9/001 using chaotic signals
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner

Abstract

A cryptation system for information transmitted through packet switching networks masks the digital information data by combining it at the transmitting station with digital data of a certain cryptation code before transmitting the so-encrypted data through the network. The system also performs an inverse decrypting processing at the receiving station using the same code. The system generates at a transmitting station and at a receiving station, starting from a given pair of password codes or user key, a certain discrete chaotic model or map of the pair of codes or key, producing dynamically updated pairs of values of codes or keys every certain number of processing steps of the chaotic map. The data to be transmitted is masked by way of a logic combination with the current dynamically updated keys at the transmitting station. The data is demasked at the receiving station by way of a logic decomposition of the digital data from the current dynamically updated key thereby returning the digital data to a normal non-encrypted condition.

Claims

1. A cryptography method for data transmitted via a packet switching network comprising the steps of:

generating at a transmitting station and at a receiving station a chaotic map from a starting key producing dynamically updated key values every predetermined number of processing steps of the chaotic map, the generating comprising

generating a sequence of chaotically evolving masking data corresponding to dynamically updated key values to be summed with information data at the transmitting station and to be subtracted from received data at the receiving station, the sequence being performed using a multilevel architecture system with dynamically updated key values output by a level representing an input key of a successive level and so forth until a last level generates the masking data, and

independently choosing a chaotic map from among a plurality of chaotic maps and using the independently chosen chaotic maps for adjacent levels;

masking data to be transmitted over the packet switching network using a logic combination with current dynamically updated key values at the transmitting station; and

demasking data received from the packet switching network station using a logic decomposition with the current dynamically updated key values.

2. A method according to claim 1, wherein an encrypted data packet comprises a header of constant length and a payload of variable length.

3. A method according to claim 2, wherein the header of the encrypted packet has at least seven fields.

4. A method according to claim 2, wherein the header of the encrypted packet has the following fields:

PID (Packet Identifier) which is an identifier which permits identifying the packet as an encrypted packet;

SID (Stream Identifier) which is an identifier of a stream to which the packet belongs, and which permits implicitly establishing when encrypting of a certain stream should stop and encrypting of another stream should start;

MID (Message Identifier) which is an identifier of a message to which the packet belongs, which permits implicitly establishing when a change of key should be done;

CC (Continuity Counter) which indicates a number of the packet within the message, and which permits, during the reception phase, detecting an eventual loss of packets because during transmission the continuity counter is incremented one unit at a time;

SL (Security Level) which indicates a chosen security level of protection of information;

HL (Header Length) which indicates a length in bytes of a header of the packet of data header contained in the payload, and which for certain types of data will be 0; and

PL (Payload Length) which indicates a length in bytes of the payload of the encrypted packet, and which serves to maintain synchronization in case of a loss of encrypted packets.

5. An encryption method for data transmitted via a packet switching network comprising the steps of:

generating at a transmitting station a chaotic map from a starting key producing dynamically updated key values every predetermined number of processing steps, the generating comprising

generating a sequence of chaotically evolving masking data corresponding to dynamically updated key values to be summed with information data at the transmitting station, the sequence being performed using a multilevel architecture system with dynamically updated key values output by a level representing an input key of a successive level and so forth until a last level generates the masking data, and

independently choosing a chaotic map from among a plurality of chaotic maps and using the independently chosen chaotic maps for adjacent levels; and

masking data to be transmitted over the packet switching network using a logic combination with current dynamically updated key values at the transmitting station.

6. A method according to claim 5, wherein an encrypted data packet comprises a header of constant length and a payload of variable length.

7. A method according to claim 6, wherein the header of the encrypted packet has at least seven fields.

8. A decrypting method for data received from a packet switching network comprising the steps of:

generating at a receiving station a chaotic map from a starting key producing dynamically updated key values every predetermined number of processing steps, the generating comprising

generating a sequence of chaotically evolving masking data corresponding to dynamically updated key values to be subtracted from received data at the receiving station, the sequence being performed using a multilevel architecture system with dynamically updated key values output by a level representing an input key of a successive level and so forth until a last level generates the masking data, and

independently choosing a chaotic map from among a plurality of chaotic maps and using the independently chosen chaotic maps for adjacent levels; and

demasking data received from the packet switching network at the receiving station using a logic decomposition with the current dynamically updated key values.

9. A method according to claim 8, wherein an encrypted data packet comprises a header of constant length and a payload of variable length.

10. An encrypted method according to claim 9, wherein the header of the crypted packet has at least seven fields.