I am somewhat confused in the reasons why one would use the real-ideal model instead of the universal composibility framework.

The UC framework seems to me, to provide a much stronger definition of security. Is there some explanation to this?


1 Answer 1


Try to prove something non-trivial using the universal composability framework and you will quickly understand why few people use it.

EDIT: Snide remarks aside, it is pretty widely acknowledge that universal composability is really hard to use in papers. It's even hard to typeset - I've seen proofs with UC functionalities that don't fit on a single page! A colleague of mine has said that proving non-trivial things using UC is like writing a web server in assembly language.

Aside from the practical difficulty of writing proofs with it, there's a more fundamental difference between UC and the real-ideal paradigm: the latter has an intuitive philosophical appeal that comports with the way people think about security. The former doesn't have the same "interpretability" IMO.

  • $\begingroup$ A part from simplicity of writing proofs, I don't understand if UC would provide stronger security. $\endgroup$ Apr 26, 2017 at 21:54
  • $\begingroup$ Hmm... I don't know enough about UC to give a rule of thumb for comparing strength of results. In some ways UC is too strong - for example, commitments are not straightforward to prove secure in UC, and most commitment schemes can't be proven secure in the basic UC model. $\endgroup$
    – pg1989
    Apr 26, 2017 at 22:10

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