### Abstract

We propose a key-evolving paradigm to deal with the key exposure problem of public key encryption schemes. The key evolving paradigm is like the one used for forward-secure digital signature schemes. Let time be divided into time periods such that at time period j, the decryptor holds the secret key SK_{j}, while the public key PK is fixed during its lifetime. At time period j, a sender encrypts a message m as 〈j, c〉, which can be decrypted only with the private key SK_{j}. When the time makes a transit from period j to j + 1, the decryptor updates its private key from SK_{j} to SK_{j+1} and deletes SK_{j} immediately. The key-evolving paradigm assures that compromise of the private key SK_{j} does not jeopardize the message encrypted at the other time periods. We propose two key-evolving public key encryption schemes with z-resilience such that compromise of z private keys does not affect confidentiality of messages encrypted in other time periods. Assuming that the DDH problem is hard, we show one scheme semantically secure against passive adversaries and the other scheme semantically secure against the adaptive chosen ciphertext attack under the random oracle.

Original language | English |
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Title of host publication | Information and Communications Security - 4th International Conference, ICICS 2002, Proceedings |

Editors | Sihan Qing, Robert Deng, Feng Bao, Jianying Zhou |

Publisher | Springer Verlag |

Pages | 61-72 |

Number of pages | 12 |

ISBN (Print) | 3540001646 |

DOIs | |

State | Published - 1 Jan 2002 |

Event | 4th International Conference on Information and Communications Security, ICICS 2002 - Singapore, Singapore Duration: 9 Dec 2002 → 12 Dec 2002 |

### 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 | 2513 |

ISSN (Print) | 0302-9743 |

ISSN (Electronic) | 1611-3349 |

### Conference

Conference | 4th International Conference on Information and Communications Security, ICICS 2002 |
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Country | Singapore |

City | Singapore |

Period | 9/12/02 → 12/12/02 |

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## Cite this

*Information and Communications Security - 4th International Conference, ICICS 2002, Proceedings*(pp. 61-72). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 2513). Springer Verlag. https://doi.org/10.1007/3-540-36159-6_6