diff --git a/rsa/bigint.c b/rsa/bigint.c
index 1f45b5a..f78c5cd 100644
--- a/rsa/bigint.c
+++ b/rsa/bigint.c
@@ -27,14 +27,13 @@ void bigint_bitwise_left_shift(bigint_t n) {
 	n.data[0] <<= 1;
 }
 
-bigint_t assignable_bigint_bitwise_left_shift(bigint_t n) {
-	bigint_t result = bigint_clone(n);
+void move_bigint_bitwise_left_shift(bigint_t n, bigint_t result) {
+	memcpy(result.data, n.data, n.len * sizeof(uint32_t));
 	size_t size = sizeof(uint32_t) * 8 - 1;
 	for (int i = result.len - 1; i > 0; i--) {
 		result.data[i] = result.data[i] << 1 | ((result.data[i - 1] & (1 << size)) >> size);
 	}
 	result.data[0] <<= 1;
-	return result;
 }
 
 // Will underflow
@@ -88,38 +87,36 @@ int is_not_zero(bigint_t n) {
 	return 0;
 }
 
-void tool(bigint_t borrow, bigint_t *y, bigint_t a) {
-	while (is_not_zero(*y)) {
+// TODO check opti
+void bigint_substraction(bigint_t a, bigint_t b, bigint_t borrow, bigint_t y) {
+	//bigint_t borrow = bigint_clone(b);
+	//bigint_t y = bigint_clone(b);
+	memcpy(borrow.data, b.data, b.len * sizeof(uint32_t));
+	memcpy(y.data, b.data, b.len * sizeof(uint32_t));
+	while (is_not_zero(y)) {
 		for (size_t i = 0; i < a.len; i++) {
-			borrow.data[i] = ~a.data[i] & y->data[i];
-			a.data[i] = a.data[i] ^ y->data[i];
+			borrow.data[i] = ~a.data[i] & y.data[i];
+			a.data[i] = a.data[i] ^ y.data[i];
 		}
-		bigint_destroy(*y);
-		*y = assignable_bigint_bitwise_left_shift(borrow);
+		move_bigint_bitwise_left_shift(borrow, y);
 	}
+	//bigint_destroy(y);
+	//bigint_destroy(borrow);
 }
 
 // TODO check opti
-void bigint_substraction(bigint_t a, bigint_t b) {
-	bigint_t borrow = bigint_clone(b);
-	bigint_t y = bigint_clone(b);
-	tool(borrow, &y, a);
-	bigint_destroy(y);
-	bigint_destroy(borrow);
-}
-
-// TODO check opti
-void custom_bigint_modulo(bigint_t a, bigint_t b, bigint_t result) {
+void custom_bigint_modulo(bigint_t a, bigint_t b, bigint_t result, bigint_t mod, bigint_t borrow_sub, bigint_t y_sub) {
 	bigint_set_zeros(result);
 	memcpy(result.data, a.data, a.len * sizeof(uint32_t));
-	bigint_t mod = bigint_clone(b);
-	if (a.len > b.len) {
-		bigint_destroy(mod);
+	//bigint_t mod = bigint_clone(b);
+	/*if (a.len > b.len) {
+		printf("useless\n");
+		//bigint_destroy(mod);
 		mod = bigint_zero(a.len);
 		memcpy(mod.data, b.data, b.len * sizeof(uint32_t));
-	}
+	}*/
 	if (bigint_cmp(result, b) < 0) {
-		bigint_destroy(mod);
+		//bigint_destroy(mod);
 		return ;
 	}
 	bigint_bitwise_left_shift(mod);
@@ -129,13 +126,13 @@ void custom_bigint_modulo(bigint_t a, bigint_t b, bigint_t result) {
 		}
 		bigint_bitwise_right_shift(mod);
 		if (bigint_cmp(result, mod) > 0) {
-			bigint_substraction(result, mod);
+			bigint_substraction(result, mod, borrow_sub, y_sub);
 		}
 	}
 	while (bigint_cmp(result, b) > 0) {
-		bigint_substraction(result, b);
+		bigint_substraction(result, b, borrow_sub, y_sub);
 	}
-	bigint_destroy(mod);
+	//bigint_destroy(mod);
 }
 
 bigint_t bigint_new(size_t len) {
@@ -222,7 +219,7 @@ void custom_bigint_mul(bigint_t a, bigint_t b, bigint_t result) {
 
 // a^e mod n
 // clean memory tricks !!!
-void custom_bigint_pow_mod(bigint_t a, bigint_t e, bigint_t n, bigint_t result, bigint_t custom, bigint_t custom2) {
+void custom_bigint_pow_mod(bigint_t a, bigint_t e, bigint_t n, bigint_t result, bigint_t custom, bigint_t custom2, bigint_t mod, bigint_t borrow_sub, bigint_t y_sub) {
 	bigint_set_zeros(result);
 	bigint_set_zeros(custom);
 	bigint_set_zeros(custom2);
@@ -235,12 +232,12 @@ void custom_bigint_pow_mod(bigint_t a, bigint_t e, bigint_t n, bigint_t result,
 	cursor--;
 	while (cursor >= 0) {
 		custom_bigint_mul(result, result, custom);
-		custom_bigint_modulo(custom, n, custom2);
+		custom_bigint_modulo(custom, n, custom2, mod, borrow_sub, y_sub);
 		bigint_set_zeros(result);
 		memcpy(result.data, custom2.data, custom2.len * sizeof(uint32_t));
 		if (e.data[cursor / 32] & 1 << (cursor % 32)) {
 			custom_bigint_mul(result, a, custom);
-			custom_bigint_modulo(custom, n, custom2);
+			custom_bigint_modulo(custom, n, custom2, mod, borrow_sub, y_sub);
 			memcpy(result.data, custom2.data, custom2.len * sizeof(uint32_t));
 		}
 		cursor -= 1;
@@ -270,12 +267,14 @@ void bulk_destroy(bigint_t x, bigint_t y, bigint_t n, bigint_t d, bigint_t two,
    }
    */
 bigint_t bigint_prime(size_t len) {
-	//bigint_t n = bigint_zero(len);
 	bigint_t n = bigint_zero(RSA_BLOCK_SIZE / 8 / sizeof(uint32_t) * 2);
 
 	bigint_set_random_bytes(n, len);
 	bigint_set_msb_and_lsb_to_one(n, len);
 
+	bigint_t mod = bigint_clone(n);
+	bigint_t borrow_sub = bigint_clone(n);
+	bigint_t y_sub = bigint_clone(n);
 	bigint_t d = bigint_clone(n);
 	d.data[0] -= 1;
 	uint32_t s = 0;
@@ -305,9 +304,9 @@ bigint_t bigint_prime(size_t len) {
 		while (bigint_cmp(a, two) < 0 || bigint_cmp(a, n_minus_two) > 0) {
 			bigint_set_random_bytes(a, len);
 		}
-		custom_bigint_pow_mod(a, d, n, x, custom, custom2);
+		custom_bigint_pow_mod(a, d, n, x, custom, custom2, mod, borrow_sub, y_sub);
 		for (uint32_t i = 0; i < s; i++) {
-			custom_bigint_pow_mod(x, two, n, y, custom, custom2);
+			custom_bigint_pow_mod(x, two, n, y, custom, custom2, mod, borrow_sub, y_sub);
 			if (!bigint_dif(y, one) && bigint_dif(x, one) && bigint_dif(x, n_minus_one)) {
 				bulk_destroy(x, y, n, d, two, one, n_minus_two, n_minus_one);
 				bigint_destroy(custom);