| Presentation | 2004-09-17 New Notions of Security for Public-Key Cryptosystems with Adversarial Random Oracles (Survey) Mototsugu NISHIOKA, |
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| PDF Download Page |  PDF download Page Link |
| Abstract(in Japanese) | (See Japanese page) |
| Abstract(in English) | We have begun studying of the security of public-key encryption schemes with adversarial random oracles. Informally, an adversarial random oracle means a random oracle that is secretly set as a trap by an adversary. We first present new security notions, SEC-ATK+ and SEC-ATK++ (SEC ∈ {OW,IND,NM}, ATK ∈ {CPA,CCA1,CCA2}), which are strengthened versions of SEC-ATK in the random oracle model. In the definitions of previous security notions (e.g., IND-CCA1, NM-CCA1, and IND-CCA2), the random oracles are given fairly. The definition of SEC-ATK+, however, allows an adversary to determine adversarial random oracles before the underlying public key is given, while the definition of SEC-ATK++ allows the adversary to determine the adversarial random oracles even after the underlying public key has been given. That is, in these attacks, the adversary can force users to use malicious random oracles to break the encryption scheme. We show that many known public-key encryption schemes that are secure in the sense of IND-CCA2 can be completely broken, or that have some cases in which they are broken, by an adversary with this additional power. It follows that "PA, IND-CCA2 〓 OW-CPA+". Thus, our new security notions provide stronger security than previous notions. Next, we present the extended notions of "semantic security" and "indistinguishable security" in order to give the conditions required for a public-key encryption scheme to be secure against an attack with adversarial random oracles, and we show that "H-IND-DCPA ⇒ IND-CPA++" and "H-IND-DCCA3 ⇒ IND-CCA2-". Finally, we present a new, practical public-key encryption scheme that is secure in the sense of IND-CCA2++. |
| Keyword(in Japanese) | (See Japanese page) |
| Keyword(in English) | public-key encryption scheme / random oracle / chosen-ciphertext attack / semantic security / indistinguishable security / plaintext awareness |
| Paper # | ISEC2004-76 |
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| Conference Information | |
| Committee | ISEC |
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| Conference Date | 2004/9/10(1days) |
| Place (in Japanese) | (See Japanese page) |
| Place (in English) | |
| Topics (in Japanese) | (See Japanese page) |
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| Paper Information | |
| Registration To | Information Security (ISEC) |
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| Language | ENG |
| Title (in Japanese) | (See Japanese page) |
| Sub Title (in Japanese) | (See Japanese page) |
| Title (in English) | New Notions of Security for Public-Key Cryptosystems with Adversarial Random Oracles (Survey) |
| Sub Title (in English) | |
| Keyword(1) | public-key encryption scheme |
| Keyword(2) | random oracle |
| Keyword(3) | chosen-ciphertext attack |
| Keyword(4) | semantic security |
| Keyword(5) | indistinguishable security |
| Keyword(6) | plaintext awareness |
| 1st Author's Name | Mototsugu NISHIOKA |
| 1st Author's Affiliation | Systems Lab, HITACHI, Ltd() |
| Date | 2004-09-17 |
| Paper # | ISEC2004-76 |
| Volume (vol) | vol.104 |
| Number (no) | 315 |
| Page | pp.pp.- |
| #Pages | 8 |
| Date of Issue | |