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TMS320F280039C: ESDSA workzone buffer

Johnny Chen
Expert 4980 points
Part Number: TMS320F280039C


Hi Champ,

I am asking for my customer, they are looking into our optimized ecdsa example (ecdsa_test_ex16).

In the example, there is a buffer declared with u32 test_workzone[4096], and user would only use verify NIST 256 and NIST 384 function.

(1). Can the workzone allocation be adjusted to the lengths used by NIST256 or NIST384 ? What does the workzone do for ?

(2). If yes, what is the length that can be adjusted for each ? NIST256  u32 test_workzone[?] & NIST384  u32 test_workzone[?]

(3). Continue to the second question, after modifying the workzone buffer size, any relevant code for the 256 and 384 needed to change ? If yes, would the expert explicitly share how ?

Thanks and regards,

Johnny

  • 0
    TI__Genius 15361 points

    This thread was resolved offline...

    Johnny Chen said:
    (1). Can the workzone allocation be adjusted to the lengths used by NIST256 or NIST384 ? What does the workzone do for ?

    yes, Size of 320 should be sufficient enough for curves <= 384 (192,256,384)

    Johnny Chen said:
    (2). If yes, what is the length that can be adjusted for each ? NIST256  u32 test_workzone[?] & NIST384  u32 test_workzone[?]

    Use data Based on Calcs from previous mails (based on eq in documentation).

    Johnny Chen said:
    (3). Continue to the second question, after modifying the workzone buffer size, any relevant code for the 256 and 384 needed to change ? If yes, would the expert explicitly share how ?

    Not that much Code Change, but the Clearing Buffersize function ( "clear(workzone,WORK_ZONE_SIZE);" ) should take this value.

    #define WORK_ZONE_SIZE  320
u32 test_workzone[WORK_ZONE_SIZE]; 
clear(workzone,WORK_ZONE_SIZE);
     

    and in algo before starting if we do clearing of workzone, use this instead. Do this as Many times as necessary.

     

    Note :  The reason why we have taken 4096 is when initial testing, things were not working, so raised the size so that we dont need to guestimate for each curve and can therefore proceed with fixing real issue.