Take the 2-minute tour ×
Cryptography Stack Exchange is a question and answer site for software developers, mathematicians and others interested in cryptography. It's 100% free, no registration required.

I was wondering what "securely realizes" means. I see this in some cryptographic papers but I don't know what it means for a protocol to "securely realize" a function $F$. Is it just a fancy way of saying "uses" or does it mean something else?

share|improve this question
1  
Generally, if the author of the paper defines the meaning of that phrase or provides a footnote with a reference, the phrase is intended to have specific technical meaning, otherwise probably not. –  Henrick Hellström Apr 24 '13 at 22:59
add comment

1 Answer 1

A standard approach in cryptography is to separate out the ideal specification (of what a scheme is supposed to achieve) from the particular instantiation (the implementation of the scheme).

To specify the security and functionality goals, sometimes cryptographers specify an "ideal functionality", which is an idealization of what we are hoping to achieve. Then, one designs a specific instantiation -- a particular scheme -- and proves that the scheme meets the goals set out in the "ideal functionality". We describe this by saying that the scheme securely realizes the ideal functionality. How to prove that is another can of worms entirely... but that's what is meant by the terminology.

This kind of approach and terminology is common in, for instance, theoretical work that adopts an "ideal world/real world" formalization (including, e.g., simulation-based security; indifferentiability; universal composability; and other lines of work in cryptography). See Wikipedia on universal composability for a high-level introduction.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.