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LPC55S69 CASPER SDK Example Performance

Question asked by Simon Ott on Jan 23, 2020
Latest reply on Feb 5, 2020 by Eugene Hiihtaja

I tested the lpc55s69_mbedtls_benchmark SDK example (from AN12445) in order to see how much speed-up ECDSA signing and verifying with the CASPER hardware accelerator could bring in my project. I  let the unmodified SDK example run on an LPC55S69 board and got the following output:  

 

"mbedTLS version 2.13.1 

fsys=96000000 

Using following implementations: 

  SHA: HASHCRYPT HW accelerated 

  [..]   

  Asymmetric encryption: CASPER HW accelerated 

  [..] 

  ECDSA-secp256r1          :    2.00 sign/s 

  ECDSA-secp256r1          :    1.67 verify/s" 

 

2 signs/s means 500ms per sign, 1.67verify/s means ~600ms per verify. This is way more than the Numbers for ECDSA-secp256r1 in the CASPER application Note (AN12445): 76ms per sign, 81ms per verify. 

 

I then commented out MBEDTLS_FREESCALE_CASPER_PKHA to see the difference when the operations run in software without CASPER and got the exact same numbers, though the printout is now "Software Implementation": 

 

"mbedTLS version 2.13.1 

fsys=96000000 

Using following implementations: 

 SHA: HASHCRYPT HW accelerated 

 [..]

 Asymmetric encryption: Software implementation 

  

ECDSA-secp256r1          :    2.00 sign/s 

ECDSA-secp256r1          :    1.67 verify/s" 

 

It seems that CASPER is not running at all in the example application. Is there a problem in the example application or did I miss something 

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