decaf no longer needs sqrt(-d) etc; may simplify port to other curves

Makefile

@@ -99,7 +99,7 @@ ifeq ($(UNAME),Darwin)
 else
 	$(LD) -shared -Wl,-soname,goldilocks.so.1 -Wl,--gc-sections -o $@ $(LIBCOMPONENTS)
 	strip --discard-all $@
-	ln -sf $@ build/goldilocks.so.1
+	ln -sf `basename $@` build/goldilocks.so.1
 endif
 
 build/timestamp:

src/ec_point.c

@@ -479,18 +479,18 @@ decaf_serialize_extensible (
     field_mul ( L3, L2, a->t ); 
     field_mul ( L2, L3, a->u ); 
     field_mul ( L0, a->x, a->z ); 
-    field_sub ( L3, L2, L0 ); 
+    field_sub ( L3, L0, L2 ); 
     field_add ( L0, a->y, a->z ); 
-    field_sub ( L1, a->y, a->z ); 
-    field_mul ( L2, L1, L0 );     
-    field_isr ( L2, L2 );          
-    field_sqr ( L1, L2 );          
-    field_mul ( L0, L1, L3 );     
-    field_mul ( L1, L2, sqrt_d_minus_1 ); 
-    field_add ( L3, L1, L1 );     
-    field_neg ( L3, L3 );          
+    field_sub ( L1, a->z, a->y ); 
+    field_mul ( L2, L1, L0 );
+    field_mulw_scc ( L1, L2, 1-EDWARDS_D );
+    field_isr ( L0, L1 );
+    field_mulw_scc ( L1, L0, 1-EDWARDS_D ); 
+    field_mul ( L2, L1, L0 );
+    field_mul ( L0, L2, L3 );
+    field_add ( L3, L1, L1 );        
     field_mul ( L2, L3, a->z );   
-    field_cond_neg ( L1, field_low_bit(L2) ); 
+    field_cond_neg ( L1, ~field_low_bit(L2) ); 
     field_mul ( L2, L1, a->y ); 
     field_add ( b, L0, L2 );
     decaf_make_even ( b );
@@ -509,15 +509,15 @@ decaf_serialize_tw_extensible (
     field_sub ( L3, L2, L0 ); 
     field_add ( L0, a->z, a->y ); 
     field_sub ( L1, a->z, a->y ); 
-    field_mul ( L2, L1, L0 );     
-    field_isr ( L2, L2 );          
-    field_sqr ( L1, L2 );          
-    field_mul ( L0, L1, L3 );     
-    field_mul ( L1, L2, sqrt_minus_d ); 
-    field_add ( L3, L1, L1 );     
-    field_neg ( L3, L3 );          
+    field_mul ( L2, L1, L0 );
+    field_mulw_scc ( L1, L2, -EDWARDS_D );
+    field_isr ( L0, L1 );
+    field_mulw_scc ( L1, L0, -EDWARDS_D ); 
+    field_mul ( L2, L1, L0 );
+    field_mul ( L0, L2, L3 );
+    field_add ( L3, L1, L1 );  
     field_mul ( L2, L3, a->z );   
-    field_cond_neg ( L1, field_low_bit(L2) ); 
+    field_cond_neg ( L1, ~field_low_bit(L2) ); 
     field_mul ( L2, L1, a->y ); 
     field_add ( b, L0, L2 );
     decaf_make_even ( b );