feat: Remove libsodium

constant-time/src/lib.rs

@@ -26,3 +26,60 @@ pub fn xor(src: &[u8]) -> impl To<[u8], ()> + '_ {
         }
     })
 }
+
+#[inline]
+pub fn memcmp(a: &[u8], b: &[u8]) -> bool {
+    a.len() == b.len()
+        && unsafe {
+            memsec::memeq(
+                a.as_ptr() as *const u8,
+                b.as_ptr() as *const u8,
+                a.len(),
+            )
+        }
+}
+
+#[inline]
+pub fn compare(a: &[u8], b: &[u8]) -> i32 {
+    assert!(a.len() == b.len());
+    unsafe { memsec::memcmp(a.as_ptr(), b.as_ptr(), a.len()) }
+}
+
+/// Interpret the given slice as a little-endian unsigned integer
+/// and increment that integer.
+///
+/// # Examples
+///
+/// ```
+/// use rosenpass_constant_time::increment as inc;
+/// use rosenpass_to::To;
+///
+/// fn testcase(v: &[u8], correct: &[u8]) {
+///   let mut v = v.to_owned();
+///   inc(&mut v);
+///   assert_eq!(&v, correct);
+/// }
+///
+/// testcase(b"", b"");
+/// testcase(b"\x00", b"\x01");
+/// testcase(b"\x01", b"\x02");
+/// testcase(b"\xfe", b"\xff");
+/// testcase(b"\xff", b"\x00");
+/// testcase(b"\x00\x00", b"\x01\x00");
+/// testcase(b"\x01\x00", b"\x02\x00");
+/// testcase(b"\xfe\x00", b"\xff\x00");
+/// testcase(b"\xff\x00", b"\x00\x01");
+/// testcase(b"\x00\x00\x00\x00\x00\x00", b"\x01\x00\x00\x00\x00\x00");
+/// testcase(b"\x00\xa3\x00\x77\x00\x00", b"\x01\xa3\x00\x77\x00\x00");
+/// testcase(b"\xff\xa3\x00\x77\x00\x00", b"\x00\xa4\x00\x77\x00\x00");
+/// testcase(b"\xff\xff\xff\x77\x00\x00", b"\x00\x00\x00\x78\x00\x00");
+/// ```
+#[inline]
+pub fn increment(v: &mut [u8]) {
+    let mut carry = 1u8;
+    for val in v.iter_mut() {
+        let (v, c) = black_box(*val).overflowing_add(black_box(carry));
+        *black_box(val) = v;
+        *black_box(&mut carry) = black_box(black_box(c) as u8);
+    }
+}