### Abstract

We study a tweakable blockcipher for arbitrarily long message (also called a tweakable enciphering scheme) that consists of a universal hash function and an expansion, a keyed function with short input and long output. Such schemes, called HCTR and HCH, have been recently proposed. They used (a variant of) the counter mode of a blockcipher for the expansion. We provide a security proof of a structure that underlies HCTR and HCH. We prove that the expansion can be instantiated with any function secure against Known-plaintext attacks (KPAs), which is called a weak pseudorandom function (WPRF). As an application of our proof, we provide efficient blockcipher-based schemes comparable to HCH and HCTR. For the double-block-length case, our result is an interesting extension of previous attempts to build a doubleblock-length cryptographic permutation using WPRF.

Original language | English |
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Title of host publication | Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) |

Pages | 252-267 |

Number of pages | 16 |

Volume | 4859 LNCS |

Publication status | Published - 2007 |

Event | 8th Annual International Conference on Cryptolology in India, INDOCRYPT 2007 - Chennai Duration: 2007 Dec 9 → 2007 Dec 13 |

### 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 | 4859 LNCS |

ISSN (Print) | 03029743 |

ISSN (Electronic) | 16113349 |

### Other

Other | 8th Annual International Conference on Cryptolology in India, INDOCRYPT 2007 |
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City | Chennai |

Period | 07/12/9 → 07/12/13 |

### Fingerprint

### Keywords

- HCH
- HCTR
- Mode of operation
- Weak pseudorandom function

### ASJC Scopus subject areas

- Computer Science(all)
- Biochemistry, Genetics and Molecular Biology(all)
- Theoretical Computer Science

### Cite this

*Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)*(Vol. 4859 LNCS, pp. 252-267). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 4859 LNCS).

**Tweakable enciphering schemes from hash-sum-expansion.** / Minematsu, Kazuhiko; Matsushima, Toshiyasu.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics).*vol. 4859 LNCS, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), vol. 4859 LNCS, pp. 252-267, 8th Annual International Conference on Cryptolology in India, INDOCRYPT 2007, Chennai, 07/12/9.

}

TY - GEN

T1 - Tweakable enciphering schemes from hash-sum-expansion

AU - Minematsu, Kazuhiko

AU - Matsushima, Toshiyasu

PY - 2007

Y1 - 2007

N2 - We study a tweakable blockcipher for arbitrarily long message (also called a tweakable enciphering scheme) that consists of a universal hash function and an expansion, a keyed function with short input and long output. Such schemes, called HCTR and HCH, have been recently proposed. They used (a variant of) the counter mode of a blockcipher for the expansion. We provide a security proof of a structure that underlies HCTR and HCH. We prove that the expansion can be instantiated with any function secure against Known-plaintext attacks (KPAs), which is called a weak pseudorandom function (WPRF). As an application of our proof, we provide efficient blockcipher-based schemes comparable to HCH and HCTR. For the double-block-length case, our result is an interesting extension of previous attempts to build a doubleblock-length cryptographic permutation using WPRF.

AB - We study a tweakable blockcipher for arbitrarily long message (also called a tweakable enciphering scheme) that consists of a universal hash function and an expansion, a keyed function with short input and long output. Such schemes, called HCTR and HCH, have been recently proposed. They used (a variant of) the counter mode of a blockcipher for the expansion. We provide a security proof of a structure that underlies HCTR and HCH. We prove that the expansion can be instantiated with any function secure against Known-plaintext attacks (KPAs), which is called a weak pseudorandom function (WPRF). As an application of our proof, we provide efficient blockcipher-based schemes comparable to HCH and HCTR. For the double-block-length case, our result is an interesting extension of previous attempts to build a doubleblock-length cryptographic permutation using WPRF.

KW - HCH

KW - HCTR

KW - Mode of operation

KW - Weak pseudorandom function

UR - http://www.scopus.com/inward/record.url?scp=38349022443&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=38349022443&partnerID=8YFLogxK

M3 - Conference contribution

SN - 9783540770251

VL - 4859 LNCS

T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

SP - 252

EP - 267

BT - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

ER -