Trouble to verify ECDSA signature, NIST P-256

Yann Garcia garcia.yann at
Sun Nov 25 13:45:42 CET 2018

Dear All,

I got issue (gcrypt/Not implementedgcrypt/Not implemented) will verifying a
signature. I have the public key, the signature and the curve.

I proceed in the following way:
1) Build public key

if ((rc = gcry_sexp_build (&public_key, NULL, "(ecc(curve \"NIST P-256\")(q
%b))\n", q_size, q)) != 0) {
      printf("Failed for %s/%s\n", gcry_strsource(rc), gcry_strerror(rc));

2) Create a context based on the public key

if (0 != (rc = gcry_mpi_ec_new(&ctx, public_key, "NIST P-256"))) {
      printf("Failed for %s/%s\n", gcry_strsource(rc), gcry_strerror(rc));

And here was the issue: I got the error message "gcrypt/Not implemented"

Can anyone provide me some hints to fix it, I have no idea how to proceed

Many thanks in advance for your help,

Best regards,
Yann Garcia
Senior Software Engineer
Microsoft Certified
Le Montespan B2
Avenue des Alpes
F-06600 Antibes, FRANCE
Tel: +33 (0)4 92 94 49 08
Mobile: +33 (0)7 61 00 77 05
Email: *yann.garcia at* <yann.garcia at>
           Yann.Garcia_EXT at
Skype: yann.garcia
Google+: garcia.yann at
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