commit 711507a72609dc2df0b4c876f6d7505443dd719a
author Manuel Pégourié-Gonnard <mpg@elzevir.fr> Fri Nov 22 17:35:28 2013 +0100
committer Manuel Pégourié-Gonnard <mpg@elzevir.fr> Fri Nov 22 17:35:28 2013 +0100
tree 4e8fc039b54aaad7c8b72cc94a5e0b1fd06b1631
parent d1bac4ae55f781a1a1bbebc6c151bdfae3d5c88b

gen_prime: ensure X = 3 mod 4 always (2x speed-up)

library/bignum.c

diff --git a/library/bignum.c b/library/bignum.c
index 2a97a59..7fac5fa 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1969,9 +1969,9 @@
             if( ret != POLARSSL_ERR_MPI_NOT_ACCEPTABLE )
                 goto cleanup;
 
-            MPI_CHK( mpi_add_int( &Y, X, 1 ) );
-            MPI_CHK( mpi_add_int(  X, X, 2 ) );
-            MPI_CHK( mpi_shift_r( &Y, 1 ) );
+            /* Keep X = 3 mod 4 */
+            MPI_CHK( mpi_add_int(  X,  X, 4 ) );
+            MPI_CHK( mpi_add_int( &Y, &Y, 2 ) );
         }
     }