question about rsa encryption

[Eric Rescorla]

Matt Crawford <crawdad at fnal.gov> writes:

> > RSA is subject to blinding attacks and several other failure modes if
> > used without padding.  For details on what that means, read the
> > cyclopedia cryptologia article on RSA.
> > 
> > http://www.disappearing-inc.com/R/rsa.html
> 
> That brings on another amateur question. In that article it says,
> "If the public exponent is less than a quarter of the modulus, RSA
> can be insecure."
> 
> Well, the public exponents I've seen range from 17 to 65537. What
> gives? Is this just one of the many weaknesses mitigated by proper
> padding?
Yes. Notice that the next sentence was:

        "You should consider padding every block encrypted with RSA
        with randomized salt, if you can; 100 bits or more will make
        any of these attacks fail completely."

-Ekr


-- 
[Eric Rescorla                                   ekr at rtfm.com]
                http://www.rtfm.com/

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