Encrypting conversion apparatus, decrypting conversion apparatus, cryptographic communication system, and electronic toll collection apparatus

• US 6,683,956 B1
• Filed: 06/01/1999
• Issued: 01/27/2004
• Est. Priority Date: 05/29/1998
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Hirahata, Shigeru, Kudo, Yoshimichi, Aikawa, Makoto, Takaragi, Kazuo
• Primary Examiner(s): Barrón, Gilberto
• Assistant Examiner(s): Zand, Kambiz
• Application Number:
  US09/323,252
• Time in Patent Office: 1,701 Days
• Field of Search: 380/42, 380/28, 380/37, 380/29, 380/284, 713/168
• US Class Current: 380/37
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 9/002 Countermeasures against attacks on cryptographic mechanisms network architectures or network communication protocols for protection against malicious traffic H04L63/1441
• CPC Class Codes: H04L 9/0618 Block ciphers, i.e. encrypting groups of characters of a plain text message using fixed encryption transformation

Abstract

An encrypting conversion apparatus, a decrypting conversion apparatus, a cryptographic communication system and an electronic toll collection apparatus are provided which are capable of changing algorithms of cryptographic conversion to hide the algorithm in use from a third party so that the apparatuses and system are resistant against a cryptographic attack from the third party and can operate at high speed. In the cryptographic communication system.

Claims

1. An encrypting conversion apparatus for inputting at least one cipher key, at least one algorithm parameter which is independent of said cipher key, and plain text data and outputting cipher text data, said encrypting apparatus comprising:

a plurality stage of encrypting conversion means for executing each of an exclusive logical sum operation, a cyclic shift operation and an addition operation at least once,

wherein;

said encrypting conversion means includes at least one of each of first to third operation means, said first operation means executes either an exclusive logical sum operation or an addition operation of input data and a portion of data generated from data of the cipher key, said second operation means executes either an exclusive logical sum operation or an addition operation of input data and a determined by a portion of said algorithm parameter, and said third operation means cyclically shifts input data by the number of bits determined dynamically based on a portion of said algorithm parameter; and

conversions which use combinations of a plurality stage of consecutive encrypting conversion means optionally selected from all of said encrypting conversion means and use the same input data and the same algorithm parameter, are all different.

2. A decrypting conversion apparatus for inputting at least one cipher key, at least one an algorithm parameter which is independent of said cipher key, and cipher text data and outputting plain text data, the apparatus comprising:

a plurality stage of decrypting conversion means for executing each of an exclusive logical sum operation, a cyclic shift operation and an addition operation at least once,

wherein;

said decrypting conversion means includes at least one of each of first to third operation means, said first operation means executes either an exclusive logical sum operation or an addition operation of input data and a portion of data generated from data of the cipher key, said second operation means executes either an exclusive logical sum operation or an addition operation of input data and a determined by a portion of said algorithm parameter, and said third operation means cyclically shifts input data by the number of bits determined dynamically based on a portion of said algorithm parameter; and

conversions which use combinations of a plurality stage of consecutive decrypting conversion means optionally selected from all of said decrypting conversion means and use the same input data and the same algorithm parameter, are all different.