1 / 12

Improvement of Hwang-Lo-Lin scheme based on an ID-based cryptosystem - PowerPoint PPT Presentation

Improvement of Hwang-Lo-Lin scheme based on an ID-based cryptosystem. No author given (Korea information security Agency) Presented by J.Liu. Outline. Introduction Review of the Hwang-Lo-Lin scheme Cryptanalysis The modified ID-based identification scheme Security analysis

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

PowerPoint Slideshow about ' Improvement of Hwang-Lo-Lin scheme based on an ID-based cryptosystem' - brent-leonard

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Improvement of Hwang-Lo-Lin scheme based on an ID-based cryptosystem

No author given

(Korea information security Agency)

Presented by J.Liu

Outline cryptosystem

• Introduction

• Review of the Hwang-Lo-Lin scheme

• Cryptanalysis

• The modified ID-based identification scheme

• Security analysis

• Performance analysis

• Conclusions

Introduction cryptosystem

• ID-based public key cryptosystem.

• Maurer-Yacobi(1996)Tseng-Jan(1998)

Hwang-Lo-Lin(2004)Horng-Liu-Liu(2005)  This Letter(2005)

• Hwang et al. developed the improved scheme was suitable for the wireless environment.

Review of the Hwang-Lo-Lin scheme cryptosystem

• TA setup the system parameters as following:

• N = p1p2 p3p4, where pi are primes and their decimal digits are between 60-70, (pi-1)/2 are odd and pair wise relatively prime.

• DLP is feasible but factoring N is infeasible.

• g is a primitive root in each GF(pi).

• h(.) is an one way hash function.

• ed = 1 mod (N) and tv = 1 mod (N).

Cont cryptosystem

• IDb, IDm: identity of base station(BS) and mobile device(M), respectively.

• sb = et  logg(IDb2) mod (N) is secret key for BS.

• sm = et  logg(IDm2) mod (N) is secret key for M.

• T: timestamp

{N, g, e, h(.)}are public parameters and keep {p1, p2 , p3, p4 , t, v, d } secret.

• Choose kR ZN*, computes Y = (IDm2)k mod N , Z = (IDb2)ksmT mod N

• Sends {IDm, Y, Z, T } to BS.

• BS computes Z’ = (Y)sbT, checks Z = Z’

If yes then… else….

?

Key points cryptosystem

Cryptanalysis cryptosystem

• Attacker forge {IDm, Y1, Z1, T’ } from a valid login message {IDm, Y, Z, T } by Y1 = YrT mod N and Z1 = ZrT’ mod N.

The modified ID-based identification scheme cryptosystem

• The parameters are the same of Hwang’s scheme, but the 4 primes have bit size more than 1024 bits. (DLP OK? about 300 decimal digits)

• M sends {IDm, Z, T} to BS, where Z = H((IDb2)smT mod N)

• BS verifies by Z = H((IDm2)sbT mod N)

Security analysis cryptosystem

• Passive replay attack: Changes timestamp T.H((IDm2)sbT mod N) H((IDm2)sbT’ mod N)

• Active replay attack: The attacker can not change Z and T without sm and sb.

• ID-stolen attack: The same with 2.

Performance analysis cryptosystem

• Without random number generator(hash function).

• Shorter message length (1/2).

• Fewer exponential operation (21).

• More suitable in wireless environment.

Conclusion cryptosystem

• Secure

• More suitable.