Paper 2003/239

Universally Composable Signatures, Certification and Authentication

Ran Canetti


Recently some efforts were made towards capturing the security requirements from digital signature schemes as an ideal functionality within a composable security framework. This modeling of digital signatures potentially has some significant analytical advantages (such as enabling component-wise analysis of complex systems that use signature schemes, as well as symbolic and automatable analysis of such systems). However, it turns out that formulating ideal functionalities that capture the properties expected from signature schemes in a way that is both sound and enjoys the above advantages is not a trivial task. This work has several contributions. We first correct some flaws in the definition of the ideal signature functionality of Canetti, 2001, andsubsequent formulations. Next we provide a minimal formalization of ``ideal certification authorities'' and show how authenticated communication can be obtained using ideal signatures and an ideal certification authority. This is done while guaranteeing full modularity (i.e., each component is analyzed as stand-alone), and in an unconditional and errorless way. This opens the door to symbolic and automated analysis of protocols for these tasks, in a way that is both modular and cryptographically sound.

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Publication info
Published elsewhere. An extended abstract of this work appears in the proceedings of CSFW 2004. The current version contains some corrections and updates of the CSFW 2004 paper.
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canetti @ watson ibm com
2004-08-15: last of 10 revisions
2003-11-19: received
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      author = {Ran Canetti},
      title = {Universally Composable Signatures, Certification and Authentication},
      howpublished = {Cryptology ePrint Archive, Paper 2003/239},
      year = {2003},
      note = {\url{}},
      url = {}
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