Content deleted Content added
Anton.bersh (talk | contribs) →Identity-based encryption algorithms: Remove link to deleted article |
clean up refs |
||
Line 1:
'''ID-based encryption''', or '''identity-based encryption''' ('''IBE'''), is an important primitive of [[ID-based cryptography]]. As such it is a type of [[public-key encryption]] in which the [[public key]] of a user is some unique information about the identity of the user (e.g. a user's email address). This means that a sender who has access to the public parameters of the system can encrypt a message using e.g. the text-value of the receiver's name or email address as a key. The receiver obtains its decryption key from a central authority, which needs to be trusted as it generates secret keys for every user.
ID-based encryption was proposed by [[Adi Shamir]] in 1984.<ref name="iseca.org">{{cite conference
| last = Shamir | first = Adi | author-link = Adi Shamir
| editor1-last = Blakley | editor1-first = G. R.
| editor2-last = Chaum | editor2-first = David
| contribution = Identity-Based Cryptosystems and Signature Schemes
| doi = 10.1007/3-540-39568-7_5
| pages = 47–53
| publisher = Springer
| series = Lecture Notes in Computer Science
| title = Advances in Cryptology, Proceedings of CRYPTO '84, Santa Barbara, California, USA, August 19–22, 1984, Proceedings
| volume = 196
| year = 1984}}</ref> He was however only able to give an instantiation of [[ID-based cryptography|identity-based signatures]]. Identity-based encryption remained an open problem for many years.
The [[pairing-based cryptography|pairing]]-based [[Boneh–Franklin scheme]]<ref>{{cite journal
| last1 = Boneh | first1 = Dan | author1-link = Dan Boneh
| last2 = Franklin | first2 = Matthew | author2-link = Matthew K. Franklin
| doi = 10.1137/S0097539701398521
| issue = 3
| journal = [[SIAM Journal on Computing]]
| mr = 2001745
| pages = 586–615
| title = Identity-based encryption from the Weil pairing
| volume = 32
| year = 2003}}</ref> and [[Cocks IBE scheme|Cocks's encryption scheme]]<ref>{{cite conference
| last = Cocks | first = Clifford C. | author-link = Clifford Cocks
| editor-last = Honary | editor-first = Bahram
| contribution = An identity based encryption scheme based on quadratic residues
| doi = 10.1007/3-540-45325-3_32
| pages = 360–363
| publisher = Springer
| series = Lecture Notes in Computer Science
| title = Cryptography and Coding, 8th IMA International Conference, Cirencester, UK, December 17–19, 2001, Proceedings
| volume = 2260
| year = 2001}}</ref> based on [[quadratic residue]]s both solved the IBE problem in 2001.
==Usage==
Identity-based systems allow any party to generate a public key from a known identity value such as an ASCII string. A trusted third party, called the [[Private Key Generator]] (PKG), generates the corresponding private keys. To operate, the PKG first publishes a master public key, and retains the corresponding '''master private key''' (referred to as ''master key''). Given the master public key, any party can compute a public key corresponding to the identity by combining the master public key with the identity value. To obtain a corresponding private key, the party authorized to use the identity ''ID'' contacts the PKG, which uses the master private key to generate the private key for identity ''ID''.
As a result, parties may encrypt messages (or verify signatures) with no prior distribution of keys between individual participants. This is extremely useful in cases where pre-distribution of authenticated keys is inconvenient or infeasible due to technical restraints. However, to decrypt or sign messages, the authorized user must obtain the appropriate private key from the PKG. A caveat of this approach is that the PKG must be highly trusted, as it is capable of generating any user's private key and may therefore decrypt (or sign) messages without authorization. Because any user's private key can be generated through the use of the third party's secret, this system has inherent [[key escrow]]. A number of variant systems have been proposed which remove the escrow including [[certificate-based encryption]],
| last = Gentry | first = Craig | author-link = Craig Gentry
| editor-last = Biham | editor-first = Eli
| contribution = Certificate-based encryption and the certificate revocation problem
| contribution-url = https://eprint.iacr.org/2003/183
| doi = 10.1007/3-540-39200-9_17
| pages = 272–293
| publisher = Springer
| series = Lecture Notes in Computer Science
| title = Advances in Cryptology – EUROCRYPT 2003, International Conference on the Theory and Applications of Cryptographic Techniques, Warsaw, Poland, May 4–8, 2003, Proceedings
| volume = 2656
| year = 2003}}</ref> [[secure key issuing cryptography]]<ref>{{cite conference
| last1 = Lee | first1 = Byoungcheon
| last2 = Boyd | first2 = Colin
| last3 = Dawson | first3 = Ed
| last4 = Kim | first4 = Kwangjo
| last5 = Yang | first5 = Jeongmo
| last6 = Yoo | first6 = Seungjae
| editor1-last = Hogan | editor1-first = James M.
| editor2-last = Montague | editor2-first = Paul
| editor3-last = Purvis | editor3-first = Martin K.
| editor4-last = Steketee | editor4-first = Chris
| contribution = Secure key issuing in ID-based cryptography
| contribution-url = https://crpit.scem.westernsydney.edu.au/abstracts/CRPITV32Lee.html
| pages = 69–74
| publisher = Australian Computer Society
| series = CRPIT
| title = ACSW Frontiers 2004, 2004 ACSW Workshops – the Australasian Information Security Workshop (AISW2004), the Australasian Workshop on Data Mining and Web Intelligence (DMWI2004), and the Australasian Workshop on Software Internationalisation (AWSI2004), Dunedin, New Zealand, January 2004
| volume = 32
| year = 2004}}</ref> and [[certificateless cryptography]].<ref>{{cite conference
| last1 = Al-Riyami | first1 = Sattam S.
| last2 = Paterson | first2 = Kenneth G.
| editor-last = Laih | editor-first = Chi-Sung
| contribution = Certificateless public key cryptography
| contribution-url = https://eprint.iacr.org/2003/126
| doi = 10.1007/978-3-540-40061-5_29
| pages = 452–473
| publisher = Springer
| series = Lecture Notes in Computer Science
| title = Advances in Cryptology – ASIACRYPT 2003, 9th International Conference on the Theory and Application of Cryptology and Information Security, Taipei, Taiwan, November 30 – December 4, 2003, Proceedings
| volume = 2894
| year = 2003}}</ref>
The steps involved are depicted in this diagram:[[File:Identity Based Encryption Steps.png|center|thumb|600px|ID Based Encryption: Offline and Online Steps]]
Line 36 ⟶ 108:
The following lists practical identity-based encryption algorithms
* [[Boneh–Franklin scheme|Boneh–Franklin]] (BF-IBE).
* [[Sakai–Kasahara scheme|Sakai–Kasahara]] (SK-IBE).<ref>{{cite
* Boneh–Boyen (BB-IBE).<ref>{{cite conference
| last1 = Boneh | first1 = Dan | author1-link = Dan Boneh
| last2 = Boyen | first2 = Xavier
| editor1-last = Cachin | editor1-first = Christian
| editor2-last = Camenisch | editor2-first = Jan
| contribution = Efficient selective-ID secure identity based encryption without random oracles
| contribution-url = https://eprint.iacr.org/2004/172
| doi = 10.1007/978-3-540-24676-3_14
| pages = 223–238
| publisher = Springer
| series = Lecture Notes in Computer Science
| title = Advances in Cryptology – EUROCRYPT 2004, International Conference on the Theory and Applications of Cryptographic Techniques, Interlaken, Switzerland, May 2–6, 2004, Proceedings
| volume = 3027
| year = 2004}}</ref>
All these algorithms have [[Provable security|security proofs]].
== Advantages ==
| |||