topic Re: ippsGFpECPrivateKey for std521r1 elliptic curve issue: Error -6. in Intel® Integrated Performance Primitives

ippsGFpECPrivateKey for std521r1 elliptic curve issue: Error -6.

jlabbe — Tue, 14 May 2024 09:09:51 GMT

Hi Team,

I'm struggling to use the method ippsGFpECPrivateKey for an elliptic curve configured following this process:

1) Create Gallois Field using:

ippsGFpInitFixed(521, ippsGFpMethod_p521r1(), gf_output);

gf_output size is 1768.

2) Create Elliptic Curve using:

ippsGFpECInitStd521r1(gf_output_GF, ec_output)

Note that ec_output was first reseat with ec_size_output (4064) extracted from

ippsGFpECGetSize(gf_output_GF, ec_size_output)

3) Create BigNum using:

ippsECCPGetSizeStd521r1(secret_key_size_output)

convert secret_key_size_output (12808) into secret_key_size_word (401)

ippsBigNumGetSize(secret_key_size_word, bn_size_output)

big_num now reseat with bn_size_output (3271)

ippsBigNumInit(secret_key_size_word, big_num)

4) Now onto using ippsGFpECPrivateKey

ippsGFpECPrivateKey(secret_key(size=3271), elliptic_curve(size=4064), randfunc, randctx)

The error returned is -6.

I can see from the documentation that -6 "Indicates an error condition if the parameter pointed to by pPrivate has a memory size that is less than the order n of the elliptic curve base point G."

This same process does produce the correct results, for std256r1 and std384r1, would somebody understand what i'm doing wrong for std521r1?

Re: ippsGFpECPrivateKey for std521r1 elliptic curve issue: Error -6.

Ruqiu_C_Intel — Wed, 15 May 2024 01:14:27 GMT

Hello,

Can you tell us your OS, IPP version, and CPU information, as well as a simple reproducer for this problem?

Re: ippsGFpECPrivateKey for std521r1 elliptic curve issue: Error -6.

jlabbe — Thu, 16 May 2024 08:18:32 GMT

Hi Ruqiu,

Thanks for the response.

I believe my problem is now gone.

Trying to create a simple reproducer, I realised that the randfunc() was the one sending back the ippStsSizeErr error...

Best Regards,

Jeremie

Re: ippsGFpECPrivateKey for std521r1 elliptic curve issue: Error -6.

Ruqiu_C_Intel — Fri, 17 May 2024 01:26:59 GMT

Hi Jeremie,

Thank you let us know the issue is gone.

And glad to know that you found out the real issue in your code when trying to create a reproducer.

Best,

Ruqiu