### Abstract

XTR public key system was introduced at Crypto 2000, which is based on a method to present elements of a subgroup of a multiplicative group of a finite field. Its application in cryptographic protocols leads to substantial savings both in communication and computational overhead without compromising security. It was shown how the use of finite extension fields and subgroups can be combined in such a way that the number of bits to be exchanged is reduced by a factor 3. In this paper we show how to more compress the communication overhead. The compressed XTR leads to a factor 6 reduction in the representation size compared to the traditional representation and achieves as twice compactness as XTR. The computational overhead of it is a little worse than that of XTR, however the compressed XTR requires only about additional 6% computational effort. If finding 4-th roots of unity is pre-computed, then the computational overhead is only 1% compared to that of original XTR. Furthermore, the required size of public key data of it reduces about 26% from that of XTR.

Original language | English |
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Title of host publication | Applied Cryptography and Network Security - 5th International Conference, ACNS 2007, Proceedings |

Pages | 420-431 |

Number of pages | 12 |

Publication status | Published - Dec 1 2007 |

Event | 5th International Conference on Applied Cryptography and Network Security, ACNS 2007 - Zhuhai, China Duration: Jun 5 2007 → Jun 8 2007 |

### Publication series

Name | Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) |
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Volume | 4521 LNCS |

ISSN (Print) | 0302-9743 |

ISSN (Electronic) | 1611-3349 |

### Other

Other | 5th International Conference on Applied Cryptography and Network Security, ACNS 2007 |
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Country | China |

City | Zhuhai |

Period | 6/5/07 → 6/8/07 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Theoretical Computer Science
- Computer Science(all)

### Cite this

*Applied Cryptography and Network Security - 5th International Conference, ACNS 2007, Proceedings*(pp. 420-431). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 4521 LNCS).