HI Tim Thanks for the reply
I think I wasnt clear enough, so here is what I am going to do. I have 32 KB of data which already has a signed hash (say Hash was generated using SHA-512). Now what I want to do is verify this signature. So this is what I will be doing 1. Compute hash over this data using SHA-512. This gives me a 512 bit hash. 2. Now I have the public key for the key pair that was used to generated the signature. I do a signature verification using RSA-1024 So the total time I will calculate as : Time for Hashing 32KB + Time for verifying it using the public key and hash = 32KB/81MB seconds + one RSA verification (0.07 ms) [The number given is for one operation and I believe thats for 1Kb as you mentioned in your earlier reply, so I can use this directly for 512 bits?) I think your earlier posts have made it clear, but I just want to be sure if I am doing the right thing. Thanks for all the help One last thing, I would want to use crypto++ library to do the same, where should I get started and how much time will it take to do the simple thing i just described Thanks once again On Oct 6, 7:26 am, Tim Lovell-Smith <[EMAIL PROTECTED]> wrote: > Sorry again, I have just shown how little I know about RSA signature > algorithms. If you're doing things the usual way (RSA PSS), you only > do one RSA decryption, not 32. RSA is still probably the limiting > factor though. :) > > On Oct 6, 9:10 pm, Tim Lovell-Smith <[EMAIL PROTECTED]> wrote: > > > Oh I'm sorry, I forgot the subject line of your post. SHA-1 and RSA. > > The most time consuming part will probably be the RSA decryption > > operations. > > > Operation Milliseconds/Operation Megacycles/Operation > > RSA 1024 Encryption 0.07 0.13 > > RSA 1024 Decryption 1.52 2.78 > > > These /Operation measures refer to time to encrypt/decrypt 1 KB > > blocks. Processing 32KB as 32 blocks of 1024 bytes, so just multiply > > the milliseconds/operation by 32. > > > On Oct 6, 9:02 pm, Tim Lovell-Smith <[EMAIL PROTECTED]> wrote: > > > > Do you mean checking the hash result against a known value, or doing a > > > digital signature (e.g. RSA/ECDSA) verification? > > > > I think that these benchmark results are for a long stream of data, so > > > you may wish to apply them with a grain of salt when guessing the time > > > taken to hash just 32KB. But if you look at MiB/Second (mebibyte/sec > > > basically megabyte/sec), this might give you a rough idea of the > > > speed. e.g. SHA-256 does about 81 MB/sec, assuming you can keep it fed > > > with data that fast. The rest is just maths - 81MB/sec is (81*32) * > > > 32KB/sec, so you might be able to do about 2400 such hashes per second > > > - although there will be more overhead in doing 2400 small chunks of > > > 32 KB than in doing one chunk of 81MB. > > > > On Oct 6, 3:39 pm, Cyptmon <[EMAIL PROTECTED]> wrote: > > > > > Hi All, > > > > > I am new to cryptography and was looking for answers to the following > > > > questions. I saw the speeds of the various cryptographic algorithms > > > > herehttp://www.cryptopp.com/benchmarks.html, and was wondering how I > > > > can use them. I had the following question in particular > > > > > If I want to calculate the time for hashing 32KB of data and then > > > > verify the signature of this hashed value, how can I do it? > > > > > Thanks for all the help in advance --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the "Crypto++ Users" Google Group. To unsubscribe, send an email to [EMAIL PROTECTED] More information about Crypto++ and this group is available at http://www.cryptopp.com. -~----------~----~----~----~------~----~------~--~---
