i want to know how many RSA 1024 bit long key decryption can a regular pentium4 computer do per second ? how to calculate RSA performance and determine its remaining time ?

  • $\begingroup$ Note that RSA 1024 is getting pretty weak (see keylength.com. I would not protect too much important data with it, please try and upgrade to higher keysizes or ECIES if you want faster asymmetric performance during decryption. $\endgroup$
    – Maarten Bodewes
    Commented Aug 25, 2012 at 23:09

1 Answer 1


Good link: Crypto++ for pentium 4

                            Milliseconds/Operation     Megacycles/Operation  
    RSA 1024 Encryptio       0.09                         0.27  
    RSA 1024 Decryption      2.28                         6.68

CPU frequency of the test platform is 2.93e+009 Hz.
I think the performance depends on the language, library and CPU architecture.

  • $\begingroup$ so 0.002 second take an RSA 1024 decryption with pentium 4 right pooya ? $\endgroup$
    – mario
    Commented Aug 21, 2012 at 20:15
  • 2
    $\begingroup$ @mario: Yes. Order of magnitude for RSA-1024 private-key operations (either decryption, or signature generation) on a Pentium 4 is 1000/second. This will vary tremendously depending on implementation (some are 10 times slower, or 100..), use of CRT (not using CRT slows down by a factor over 3), and use of countermeasures against timing attacks and other side channels. Public-key operations (encryption or signature verification) may be like 50 times faster. $\endgroup$
    – fgrieu
    Commented Aug 21, 2012 at 21:32
  • $\begingroup$ @mario:If you are using Crypto++ library, yes. $\endgroup$ Commented Aug 22, 2012 at 1:08

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