crypto.aes module

vlib/crypto/internal/subtle/aliasing.v

@@ -0,0 +1,32 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+// Package subtle implements functions that are often useful in cryptographic
+// code but require careful thought to use correctly.
+
+module subtle
+
+// any_overlap reports whether x and y share memory at any (not necessarily
+// corresponding) index. The memory beyond the slice length is ignored.
+pub fn any_overlap(x, y []byte) bool {
+	// NOTE: Remember to come back to this (joe-c)
+	return x.len > 0 && y.len > 0 &&
+		// &x.data[0] <= &y.data[y.len-1] &&
+		// &y.data[0] <= &x.data[x.len-1]
+		&x[0] <= &y[y.len-1] &&
+		&y[0] <= &x[x.len-1]
+}
+
+// inexact_overlap reports whether x and y share memory at any non-corresponding
+// index. The memory beyond the slice length is ignored. Note that x and y can
+// have different lengths and still not have any inexact overlap.
+//
+// inexact_overlap can be used to implement the requirements of the crypto/cipher
+// AEAD, Block, BlockMode and Stream interfaces.
+pub fn inexact_overlap(x, y []byte) bool {
+	if x.len == 0 || y.len == 0 || &x[0] == &y[0] {
+		return false
+	}
+	return any_overlap(x, y)
+}