v0.15.0

internals.go

@@ -93,9 +93,11 @@ func fillRandBytes(b []byte) {
 
 // Wipes a byte slice with zeroes.
 func wipeBytes(buf []byte) {
-	// Iterate over the slice...
-	for i := 0; i < len(buf); i++ {
-		// ... setting each element to zero.
-		buf[i] = byte(0)
+	if len(buf) == 0 {
+		return
+	}
+	buf[0] = 0
+	for bp := 1; bp < len(buf); bp *= 2 {
+		copy(buf[bp:], buf[:bp])
 	}
 }

memguard.go

@@ -803,6 +803,15 @@ func Trim(b *LockedBuffer, offset, size int) (*LockedBuffer, error) {
 	return newBuf, nil
 }
 
+/*
+WipeBytes zeroes out a given byte slice. It is recommeded that you call WipeBytes on slices after utilizing the Copy or CopyAt methods.
+
+Due to the nature of memory allocated by the Go runtime, WipeBytes cannot guarantee that the data does not exist elsewhere in memory. Therefore, your program should aim to (when possible) store sensitive data only in LockedBuffers.
+*/
+func WipeBytes(b []byte) {
+	wipeBytes(b)
+}
+
 /*
 DestroyAll calls Destroy on all LockedBuffers that have not already been destroyed.
 

memguard_test.go

@@ -693,6 +693,27 @@ func TestTrim(t *testing.T) {
 	}
 }
 
+func TestWipeBytes(t *testing.T) {
+	// Create random byte slice.
+	b := make([]byte, 32)
+	fillRandBytes(b)
+
+	// Wipe it.
+	WipeBytes(b)
+
+	// Check.
+	if !bytes.Equal(b, make([]byte, 32)) {
+		t.Error("unsuccessful wipe")
+	}
+
+	// Try with empty list.
+	ebuf := make([]byte, 0)
+	WipeBytes(ebuf)
+	if len(ebuf) != 0 || cap(ebuf) != 0 {
+		t.Error("changes made to zero-sized slice")
+	}
+}
+
 func TestCatchInterrupt(t *testing.T) {
 	CatchInterrupt(func() {})