curve25519 and ed25519 low memory

configure.ac

@@ -680,17 +680,28 @@ then
 fi
 
 
+# for using memory optimization setting on both curve25519 and ed25519
+ENABLED_CURVED25519_SMALL=no
+
 # CURVE25519
 AC_ARG_ENABLE([curve25519],
     [AS_HELP_STRING([--enable-curve25519],[Enable Curve25519 (default: disabled)])],
     [ ENABLED_CURVE25519=$enableval ],
     [ ENABLED_CURVE25519=no ]
     )
 
+
+if test "$ENABLED_CURVE25519" = "small"
+then
+    AM_CFLAGS="$AM_CFLAGS -DCURVED25519_SMALL"
+    ENABLED_CURVED25519_SMALL=yes
+    ENABLED_CURVE25519=yes
+fi
+
 if test "$ENABLED_CURVE25519" = "yes"
 then
-    ENABLED_FEMATH=yes
     AM_CFLAGS="$AM_CFLAGS -DHAVE_CURVE25519"
+    ENABLED_FEMATH=yes
 fi
 
 
@@ -705,6 +716,13 @@ AC_ARG_ENABLE([ed25519],
     )
 
 
+if test "$ENABLED_ED25519" = "small"
+then
+    AM_CFLAGS="$AM_CFLAGS -DCURVED25519_SMALL"
+    ENABLED_CURVED25519_SMALL=yes
+    ENABLED_ED25519=yes
+fi
+
 if test "$ENABLED_ED25519" = "yes"
 then
     if test "$ENABLED_SHA512" = "no"
@@ -716,8 +734,8 @@ then
     AM_CFLAGS="$AM_CFLAGS -DHAVE_ED25519"
 fi
 
-
 AM_CONDITIONAL([BUILD_ED25519], [test "x$ENABLED_ED25519" = "xyes"])
+AM_CONDITIONAL([BUILD_CURVED25519_SMALL], [test "x$ENABLED_CURVED25519_SMALL" = "xyes"])
 AM_CONDITIONAL([BUILD_FEMATH],  [test "x$ENABLED_FEMATH" = "xyes"])
 AM_CONDITIONAL([BUILD_GEMATH],  [test "x$ENABLED_GEMATH" = "xyes"])
 

src/include.am

@@ -176,12 +176,20 @@ src_libwolfssl_la_SOURCES += wolfcrypt/src/ed25519.c
 endif
 
 if BUILD_FEMATH
+if BUILD_CURVED25519_SMALL
+src_libwolfssl_la_SOURCES += wolfcrypt/src/fe_low_mem.c
+else
 src_libwolfssl_la_SOURCES += wolfcrypt/src/fe_operations.c
 endif
+endif
 
 if BUILD_GEMATH
+if BUILD_CURVED25519_SMALL
+src_libwolfssl_la_SOURCES += wolfcrypt/src/ge_low_mem.c
+else
 src_libwolfssl_la_SOURCES += wolfcrypt/src/ge_operations.c
 endif
+endif
 
 if BUILD_LIBZ
 src_libwolfssl_la_SOURCES += wolfcrypt/src/compress.c

wolfcrypt/src/curve25519.c

@@ -46,72 +46,6 @@ const curve25519_set_type curve25519_sets[] = {
 };
 
 
-/* internal function */
-static int curve25519(unsigned char* q, unsigned char* n, unsigned char* p)
-{
-  unsigned char e[32];
-  unsigned int i;
-  fe x1;
-  fe x2;
-  fe z2;
-  fe x3;
-  fe z3;
-  fe tmp0;
-  fe tmp1;
-  int pos;
-  unsigned int swap;
-  unsigned int b;
-
-  for (i = 0;i < 32;++i) e[i] = n[i];
-  e[0] &= 248;
-  e[31] &= 127;
-  e[31] |= 64;
-
-  fe_frombytes(x1,p);
-  fe_1(x2);
-  fe_0(z2);
-  fe_copy(x3,x1);
-  fe_1(z3);
-
-  swap = 0;
-  for (pos = 254;pos >= 0;--pos) {
-    b = e[pos / 8] >> (pos & 7);
-    b &= 1;
-    swap ^= b;
-    fe_cswap(x2,x3,swap);
-    fe_cswap(z2,z3,swap);
-    swap = b;
-
-    /* montgomery */
-	fe_sub(tmp0,x3,z3);
-	fe_sub(tmp1,x2,z2);
-	fe_add(x2,x2,z2);
-	fe_add(z2,x3,z3);
-	fe_mul(z3,tmp0,x2);
-	fe_mul(z2,z2,tmp1);
-	fe_sq(tmp0,tmp1);
-	fe_sq(tmp1,x2);
-	fe_add(x3,z3,z2);
-	fe_sub(z2,z3,z2);
-	fe_mul(x2,tmp1,tmp0);
-	fe_sub(tmp1,tmp1,tmp0);
-	fe_sq(z2,z2);
-	fe_mul121666(z3,tmp1);
-	fe_sq(x3,x3);
-	fe_add(tmp0,tmp0,z3);
-	fe_mul(z3,x1,z2);
-	fe_mul(z2,tmp1,tmp0);
-  }
-  fe_cswap(x2,x3,swap);
-  fe_cswap(z2,z3,swap);
-
-  fe_invert(z2,z2);
-  fe_mul(x2,x2,z2);
-  fe_tobytes(q,x2);
-
-  return 0;
-}
-
 
 int wc_curve25519_make_key(RNG* rng, int keysize, curve25519_key* key)
 {
@@ -138,7 +72,7 @@ int wc_curve25519_make_key(RNG* rng, int keysize, curve25519_key* key)
   key->k.point[31] &= 127;
   key->k.point[31] |= 64;
 
-  /*compute public key*/
+  /* compute public key */
   ret = curve25519(p, key->k.point, basepoint);
 
   /* store keys in big endian format */