tinycrypt.patch

diff --git a/config.mk b/config.mk
index a5b9fb7..00ca1cf 100644
--- a/config.mk
+++ b/config.mk
@@ -8,7 +8,7 @@
 
 # EDIT HERE:
 CC:=gcc
-CFLAGS:=-Os -std=c99 -Wall -Wextra -D_ISOC99_SOURCE -MMD -I../lib/include/ -I../lib/source/ -I../tests/include/
+CFLAGS:=-Os -flto -std=c99 -Wall -Wextra -D_ISOC99_SOURCE -MMD -I../lib/include/ -I../lib/source/ -I../tests/include/
 vpath %.c ../lib/source/
 ENABLE_TESTS=true
 
diff --git a/lib/Makefile b/lib/Makefile
index 9c4d8e2..9da863c 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -9,20 +9,23 @@
 include ../config.mk
 
 # Edit the OBJS content to add/remove primitives needed from TinyCrypt library:
-OBJS:=aes_decrypt.o \
-	aes_encrypt.o \
-	cbc_mode.o \
-	ctr_mode.o \
-	ctr_prng.o \
-	hmac.o \
-	hmac_prng.o \
-	sha256.o \
-	ecc.o \
-	ecc_dh.o \
-	ecc_dsa.o \
-	ccm_mode.o \
-	cmac_mode.o \
-	utils.o
+# OBJS:=aes_decrypt.o \
+# 	aes_encrypt.o \
+# 	cbc_mode.o \
+# 	ctr_mode.o \
+# 	ctr_prng.o \
+# 	hmac.o \
+# 	hmac_prng.o \
+# 	sha256.o \
+# 	ecc.o \
+# 	ecc_dh.o \
+# 	ecc_dsa.o \
+# 	ccm_mode.o \
+# 	cmac_mode.o \
+# 	utils.o
+
+OBJS:= ecc_dsa.o \
+  	ecc.o
 
 DEPS:=$(OBJS:.o=.d)
 
diff --git a/lib/include/tinycrypt/ecc_platform_specific.h b/lib/include/tinycrypt/ecc_platform_specific.h
index e2c8823..a55adf4 100644
--- a/lib/include/tinycrypt/ecc_platform_specific.h
+++ b/lib/include/tinycrypt/ecc_platform_specific.h
@@ -74,7 +74,7 @@
  * for some platforms, such as Unix and Linux. For other platforms, you may need
  * to provide another PRNG function.
 */
-#define default_RNG_defined 1
+#define default_RNG_defined 0
 
 int default_CSPRNG(uint8_t *dest, unsigned int size);
 
diff --git a/lib/source/ecc.c b/lib/source/ecc.c
index 46080bf..dc996aa 100644
--- a/lib/source/ecc.c
+++ b/lib/source/ecc.c
@@ -408,7 +408,7 @@ static void vli_modInv_update(uECC_word_t *uv,
 void uECC_vli_modInv(uECC_word_t *result, const uECC_word_t *input,
 		     const uECC_word_t *mod, wordcount_t num_words)
 {
-	uECC_word_t a[NUM_ECC_WORDS], b[NUM_ECC_WORDS];
+    uECC_word_t a[NUM_ECC_WORDS], b[NUM_ECC_WORDS];
 	uECC_word_t u[NUM_ECC_WORDS], v[NUM_ECC_WORDS];
 	cmpresult_t cmpResult;
 
@@ -422,11 +422,27 @@ void uECC_vli_modInv(uECC_word_t *result, const uECC_word_t *input,
 	uECC_vli_clear(u, num_words);
 	u[0] = 1;
 	uECC_vli_clear(v, num_words);
+	/* StepOverflow
+	 * We use this div-slide as a marker for when the while loop starts.
+	 * This serves as a simulated signal that would be visible to an attacker
+	 * using a page-fault controlled-channel when the function is called from main
+	 */
+	int r = 5;
+    unsigned long dividend = 1000000;
+    __asm__ volatile(
+        "movq %[dividend], %%rax\n\t"  // load dividend into RAX
+        "xorq %%rdx, %%rdx\n\t"        // clear RDX (high bits)
+        ".rept 105;\n\t"
+        "divq %%rbx;\n\t" //requires "movq (%0), %%rbx\n\t"
+        ".endr;\n\t"
+        :: "b" (&r), [dividend]"r"(dividend)
+        : "rax", "rdx"
+    );
 	while ((cmpResult = uECC_vli_cmp_unsafe(a, b, num_words)) != 0) {
 		if (EVEN(a)) {
 			uECC_vli_rshift1(a, num_words);
-      			vli_modInv_update(u, mod, num_words);
-    		} else if (EVEN(b)) {
+      		vli_modInv_update(u, mod, num_words);
+  		} else if (EVEN(b)) {
 			uECC_vli_rshift1(b, num_words);
 			vli_modInv_update(v, mod, num_words);
 		} else if (cmpResult > 0) {
@@ -434,18 +450,18 @@ void uECC_vli_modInv(uECC_word_t *result, const uECC_word_t *input,
 			uECC_vli_rshift1(a, num_words);
 			if (uECC_vli_cmp_unsafe(u, v, num_words) < 0) {
         			uECC_vli_add(u, u, mod, num_words);
-      			}
-      			uECC_vli_sub(u, u, v, num_words);
-      			vli_modInv_update(u, mod, num_words);
-    		} else {
-      			uECC_vli_sub(b, b, a, num_words);
-      			uECC_vli_rshift1(b, num_words);
-      			if (uECC_vli_cmp_unsafe(v, u, num_words) < 0) {
-        			uECC_vli_add(v, v, mod, num_words);
-      			}
-      			uECC_vli_sub(v, v, u, num_words);
-      			vli_modInv_update(v, mod, num_words);
-    		}
+      		}
+      		uECC_vli_sub(u, u, v, num_words);
+      		vli_modInv_update(u, mod, num_words);
+  		} else {
+ 			uECC_vli_sub(b, b, a, num_words);
+ 			uECC_vli_rshift1(b, num_words);
+ 			if (uECC_vli_cmp_unsafe(v, u, num_words) < 0) {
+     			uECC_vli_add(v, v, mod, num_words);
+ 			}
+ 			uECC_vli_sub(v, v, u, num_words);
+ 			vli_modInv_update(v, mod, num_words);
+  		}
   	}
   	uECC_vli_set(result, u, num_words);
 }
@@ -612,7 +628,7 @@ void vli_mmod_fast_secp256r1(unsigned int *result, unsigned int*product)
 		}
 		while (carry < 0);
 	} else  {
-		while (carry || 
+		while (carry ||
 		       uECC_vli_cmp_unsafe(curve_secp256r1.p, result, NUM_ECC_WORDS) != 1) {
 			carry -= uECC_vli_sub(result, result, curve_secp256r1.p, NUM_ECC_WORDS);
 		}
@@ -729,7 +745,7 @@ static void XYcZ_addC(uECC_word_t * X1, uECC_word_t * Y1,
 void EccPoint_mult(uECC_word_t * result, const uECC_word_t * point,
 		   const uECC_word_t * scalar,
 		   const uECC_word_t * initial_Z,
-		   bitcount_t num_bits, uECC_Curve curve) 
+		   bitcount_t num_bits, uECC_Curve curve)
 {
 	/* R0 and R1 */
 	uECC_word_t Rx[2][NUM_ECC_WORDS];
@@ -937,6 +953,3 @@ int uECC_compute_public_key(const uint8_t *private_key, uint8_t *public_key,
 	curve->num_bytes, curve->num_bytes, _public + curve->num_words);
 	return 1;
 }
-
-
-
diff --git a/tests/Makefile b/tests/Makefile
index eff5a88..705135c 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -16,7 +16,8 @@ TEST_DEPS:=$(TEST_SOURCE:.c=.d)
 TEST_BINARY:=$(TEST_SOURCE:.c=$(DOTEXE))
 
 # Edit the 'all' content to add/remove tests needed from TinyCrypt library:
-all: $(TEST_BINARY)
+#all: $(TEST_BINARY)
+all: ecc_modinv$(DOTEXE)
 
 clean:
 	-$(RM) $(TEST_BINARY) $(TEST_OBJECTS) $(TEST_DEPS)
@@ -63,5 +64,7 @@ test_ecc_dsa$(DOTEXE): test_ecc_dsa.o ecc.o utils.o ecc_dh.o \
 		ecc_dsa.o sha256.o test_ecc_utils.o ecc_platform_specific.o
 	$(LINK.o) $^ $(LOADLIBES) $(LDLIBS) -o $@
 
+ecc_modinv$(DOTEXE): ecc_modinv.o ecc.o
+	$(LINK.o) $^ $(LOADLIBES) $(LDLIBS) -o $@
 
 -include $(TEST_DEPS)
diff --git a/tests/ecc_modinv.c b/tests/ecc_modinv.c
new file mode 100644
index 0000000..1d0264c
--- /dev/null
+++ b/tests/ecc_modinv.c
@@ -0,0 +1,47 @@
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include <tinycrypt/ecc.h>
+#include <tinycrypt/ecc_platform_specific.h>
+#include <tinycrypt/ecc_dsa.h>
+#include <tinycrypt/ecc_dh.h>
+
+int main(int argc, char *argv[]){
+   	const struct uECC_Curve_t * curve = uECC_secp256r1();
+
+    uECC_word_t k[NUM_ECC_WORDS] = {0};
+
+    if (argc > NUM_ECC_WORDS + 1) {
+        printf("Provide 1 to %d 32-bit hex values.\n", NUM_ECC_WORDS);
+        return 1;
+    }
+
+    // Fill from LSB upward
+    for (int i = 1; i < argc; i++) {
+        unsigned long value = strtoul(argv[i], NULL, 16);
+        k[i - 1] = (uECC_word_t)value;
+    }
+
+    // Print result for verification
+    printf("k =\n");
+    for (int i = NUM_ECC_WORDS - 1; i >= 0; i--) {
+        printf("%08x ", (unsigned int)k[i]);
+    }
+    printf("\n");
+
+	printf("Waiting for you to press enter...\n");
+    int c = 0;
+    while ((c = getchar()) != '\n' && c != EOF) {}
+
+    uECC_vli_modInv(k, k, curve->n, NUM_ECC_WORDS);
+    // uECC_word_t tmp[2*NUM_ECC_WORDS];
+    // tmp[0] = 0;
+    // uECC_vli_mmod(k, tmp, curve->n, NUM_ECC_WORDS);
+    printf("Waiting for you to press enter...\n");
+    c = 0;
+    while ((c = getchar()) != '\n' && c != EOF) {}
+    return 0;
+}