Efficient Trapdoor Commitment as Secure as Factoring with Useful Properties

Taek-Young YOUN  Young-Ho PARK  Jongin LIM  

IEICE TRANSACTIONS on Information and Systems   Vol.E92-D   No.12   pp.2520-2523
Publication Date: 2009/12/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E92.D.2520
Print ISSN: 0916-8532
Type of Manuscript: LETTER
Category: Application Information Security
security,  trapdoor commitment,  key exposure freeness,  strong trapdoor opening,  integer factoring problem,  

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Trapdoor commitment schemes are widely used for adding valuable properties to ordinary signatures or enhancing the security of weakly secure signatures. In this letter, we propose a trapdoor commitment scheme based on RSA function, and prove its security under the hardness of the integer factoring. Our scheme is very efficient in computing a commitment. Especially, it requires only three multiplications for evaluating a commitment when e=3 is used as a public exponent of RSA function. Moreover, our scheme has two useful properties, key exposure freeness and strong trapdoor opening, which are useful for designing secure chameleon signature schemes and converting a weakly secure signature to a strongly secure signature, respectively.