Remove redundant checks, save a few muls
ecp_mul() already checks for this, and this check is not going away, so no
need to do it twice (didn't even result in better error reporting)
diff --git a/library/ecdsa.c b/library/ecdsa.c
index 835d3de..3fddc4e 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -499,13 +499,6 @@
}
/*
- * Additional precaution: make sure Q is valid
- * For ops count, group that together with step 4
- */
- ECDSA_BUDGET( MBEDTLS_ECP_OPS_CHK + MBEDTLS_ECP_OPS_INV + 2 );
- MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) );
-
- /*
* Step 3: derive MPI from hashed message
*/
MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) );
@@ -513,6 +506,8 @@
/*
* Step 4: u1 = e / s mod n, u2 = r / s mod n
*/
+ ECDSA_BUDGET( MBEDTLS_ECP_OPS_CHK + MBEDTLS_ECP_OPS_INV + 2 );
+
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pu1, &e, &s_inv ) );