On Fri, 3 May 2013 23:27, robe...@broadcom.com said: > I am using Libgcrypt 1.5.2 with gcc v 4.5.3 on Cygwin to use the MPI > functions. Can you please provide some guidance on how to handle > signed and negative MPIs? I cannot seem to get a negative MPI, which
Negative numbers are supported by the MPI subsystem but a rarely used. There is a macro mpi_is_neg to test for it. We have no explict function to negate an MPI. You would need to resort to somthing like void make_negative (gcry_mpi_t value) { gcry_mpi_t zero = gcry_mpi_new (0); gcry_mpi_sub (value, zero, value); gcry_mpi_release (zero); } Not pretty elegant or fast given that it only needs to toggle a bit. For the use of some macros the sign bit is exposed, so you could use a bad hack to do it faster. > As an alternative, Is it possible to use the ecc functions with a custom > random number generator algorithm? Are you looking into deterministic DSA, similar to the draft-pornin-deterministic-dsa-01 I-D? We recently started a discussion on gcrypt-de...@gnupg.org about this. That ML would anyway be a better place for your questions. Shalom-Salam, Werner -- Die Gedanken sind frei. Ausnahmen regelt ein Bundesgesetz. _______________________________________________ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users