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CC2642R: Curve25519 vs P-256

Mark Ackerson
Genius 10190 points
Part Number: CC2642R

Customer evaluated Curve25519 implementation for ECDH and compared it to P-256. The P-256 calculations are reasonable.  Curve25519 is supposed to be more efficient than P-256, but the power was significantly higher.  In fact, this is approximately the power we were seeing when we implemented Curve25519 in C.

Secondly CC2642R SimpleLink™ Bluetooth® 5 low energy Wireless MCU datasheet Page 28 notes "Montgomery form (hardware support for multiplication), such as: Curve25519".  What does this exactly mean?

Regards,
Mark

  • 0
    TI__Mastermind 19135 points
    Hello Mark,

    I can help you with this, can you help me recreate this on my setup?

    Regards,
    AB
  • 0 in reply to AB
    TI__Genius 10190 points

    Hi AB,

    Thanks for the reply but we figured it out. It turns out that they were using a short key for the ECDH calculation, which gave an abnormally low value for energy consumed.  When they used a representative key, the numbers came up to where we expected them to be. ECDH was around 1800 uJ. Curve2519 multiply came in around 900 uJ.

    Regards,
    Mark