crypto.hmac: implement hmac.equal/2 too

vlib/crypto/internal/subtle/comparison_test.v

@@ -0,0 +1,65 @@
+module subtle
+
+fn test_constant_time_byte_eq() {
+	assert constant_time_byte_eq(0, 0) == 1
+	assert constant_time_byte_eq(1, 1) == 1
+	assert constant_time_byte_eq(255, 255) == 1
+	assert constant_time_byte_eq(255, 1) == 0
+	assert constant_time_byte_eq(1, 255) == 0
+	assert constant_time_byte_eq(2, 1) == 0
+}
+
+fn test_constant_time_eq() {
+	assert constant_time_eq(0, 0) == 1
+	assert constant_time_eq(255, 255) == 1
+	assert constant_time_eq(65536, 65536) == 1
+	assert constant_time_eq(-1, -1) == 1
+	assert constant_time_eq(-256, -256) == 1
+	assert constant_time_eq(0, 1) == 0
+}
+
+fn test_constant_time_select() {
+	assert constant_time_select(1, 1, 0) == 1
+	assert constant_time_select(1, 1, 255) == 1
+	assert constant_time_select(1, 1, 255 * 255) == 1
+	assert constant_time_select(1, 2, 0) == 2
+	assert constant_time_select(1, 2, 255) == 2
+	assert constant_time_select(1, 2, 255 * 255) == 2
+	//
+	assert constant_time_select(0, 1, 0) == 0
+	assert constant_time_select(0, 1, 255) == 255
+	assert constant_time_select(0, 1, 255 * 255) == 255 * 255
+	assert constant_time_select(0, 2, 0) == 0
+	assert constant_time_select(0, 2, 255) == 255
+	assert constant_time_select(0, 2, 255 * 255) == 255 * 255
+}
+
+fn test_constant_time_compare() {
+	assert constant_time_compare([byte(1), 2, 3], [byte(1), 2, 3]) == 1
+	assert constant_time_compare([byte(1), 2, 3], [byte(1), 2, 9]) == 0
+	assert constant_time_compare([byte(1), 2, 3], [byte(1), 2, 3, 4]) == 0
+	assert constant_time_compare([byte(1), 2, 3], [byte(1), 2]) == 0
+}
+
+fn test_constant_time_copy() {
+	y := [byte(3), 4, 5]
+	mut x := [byte(0), 0, 0]
+	constant_time_copy(0, mut x, y)
+	assert x == [byte(0), 0, 0]
+	constant_time_copy(1, mut x, y)
+	assert x == y
+	assert x == [byte(3), 4, 5]
+}
+
+fn test_constant_time_less_or_eq() {
+	assert constant_time_less_or_eq(1, 1) == 1
+	assert constant_time_less_or_eq(1, 2) == 1
+	assert constant_time_less_or_eq(1, 3) == 1
+	assert constant_time_less_or_eq(255, 255) == 1
+	assert constant_time_less_or_eq(255, 256) == 1
+	assert constant_time_less_or_eq(255, 257) == 1
+	assert constant_time_less_or_eq(1, 0) == 0
+	assert constant_time_less_or_eq(2, 1) == 0
+	assert constant_time_less_or_eq(3, 2) == 0
+	assert constant_time_less_or_eq(255, 3) == 0
+}