add first ZKP including test case

1 files changed, 45 insertions, 3 deletions

diff --git a/crypto.c b/crypto.c
index e78032e..7f2940a 100644
--- a/crypto.c
+++ b/crypto.c
@@ -243,17 +243,19 @@ brandt_ec_skey_create (gcry_mpi_t* skey)
 {
         gcry_sexp_t  s_keyparam;
         gcry_sexp_t  priv_sexp;
-        gcry_mpi_t   d;
         gcry_error_t rc;
 
         rc = gcry_sexp_build (&s_keyparam, NULL, "(genkey(ecc(curve \"" CURVE "\")"
                               "(flags)))");
         brandt_assert_gpgerr (rc);
+
         rc = gcry_pk_genkey (&priv_sexp, s_keyparam);
         brandt_assert_gpgerr (rc);
         gcry_sexp_release (s_keyparam);
+
         rc = key_from_sexp (skey, priv_sexp, "private-key", "d");
         brandt_assert_gpgerr (rc);
+
         gcry_sexp_release (priv_sexp);
 }
 
@@ -268,10 +270,10 @@ brandt_ec_pkey_compute (gcry_mpi_point_t* pkey, const gcry_mpi_t skey)
 void
 brandt_ec_keypair_create (gcry_mpi_point_t* pkey, gcry_mpi_t* skey)
 {
-        gcry_error_t rc;
+        gcry_ctx_t   ctx;
         gcry_sexp_t  s_keyparam;
         gcry_sexp_t  priv_sexp;
-        gcry_ctx_t   ctx;
+        gcry_error_t rc;
 
         rc = gcry_sexp_build (&s_keyparam, NULL, "(genkey(ecc(curve \"" CURVE "\")"
                               "(flags)))");
@@ -294,6 +296,46 @@ brandt_ec_keypair_create (gcry_mpi_point_t* pkey, gcry_mpi_t* skey)
 }
 
 
+void
+brandt_ec_keypair_create_base (gcry_mpi_point_t* pkey, gcry_mpi_t* skey, const gcry_mpi_point_t base)
+{
+        brandt_ec_skey_create(skey);
+        brandt_assert(*skey);
+        *pkey = gcry_mpi_point_new(0);
+        brandt_assert(*pkey);
+        gcry_mpi_ec_mul(*pkey, *skey, base, ec_ctx);
+}
+
+
+int
+brandt_ec_point_cmp (const gcry_mpi_point_t a, const gcry_mpi_point_t b)
+{
+        int ret = 1;
+        gcry_mpi_t ax = gcry_mpi_new(0);
+        gcry_mpi_t bx = gcry_mpi_new(0);
+        gcry_mpi_t ay = gcry_mpi_new(0);
+        gcry_mpi_t by = gcry_mpi_new(0);
+
+        brandt_assert (a && b);
+        if (!ax || !bx || !ay || !by)
+        {
+                weprintf("could not init point in point_cmp");
+                return 1;
+        }
+
+        if (!gcry_mpi_ec_get_affine(ax, ay, a, ec_ctx) && !gcry_mpi_ec_get_affine(bx, by, b, ec_ctx))
+        {
+                ret = gcry_mpi_cmp(ax, bx) || gcry_mpi_cmp(ay, by);
+        }
+
+        gcry_mpi_release(ax);
+        gcry_mpi_release(bx);
+        gcry_mpi_release(ay);
+        gcry_mpi_release(by);
+        return ret;
+}
+
+
 /**
  * Convert the given private key from the network format to the
  * S-expression that can be used by libgcrypt.