v0.1 - initial commit

encoders_test.go

@@ -0,0 +1,56 @@
+package winpwn
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestFindXORKeyAvoidsBadChars(t *testing.T) {
+	data := []byte{0x00, 0x0A, 0x0D, 0x41, 0x42}
+	badChars := []byte{0x00, 0x0A, 0x0D}
+
+	key, err := FindXORKey(data, badChars)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	encoded := Xor(data, []byte{key})
+	if HasBadChars(encoded, badChars) {
+		t.Errorf("encoded output %x still contains a bad char (key=0x%02x)", encoded, key)
+	}
+}
+
+func TestEncodeXORRoundTrip(t *testing.T) {
+	data := []byte("the quick brown fox")
+	badChars := []byte{0x00, 0x0A, 0x0D, 0x20} // also avoid spaces, for fun
+
+	encoded, key, err := EncodeXOR(data, badChars)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if HasBadChars(encoded, badChars) {
+		t.Errorf("encoded output still has bad chars")
+	}
+
+	decoded := Xor(encoded, []byte{key})
+	if !bytes.Equal(decoded, data) {
+		t.Errorf("decoded = %q, want %q", decoded, data)
+	}
+}
+
+func TestFindXORKeyImpossible(t *testing.T) {
+	// Every byte 0..255 appears in data, so no key can avoid every byte
+	// being a bad char if badChars also covers every value the key could
+	// produce -- construct a case that's provably impossible: data
+	// contains every byte value, and badChars also contains every byte
+	// value, so any key XORed against some data byte lands on a bad byte.
+	data := make([]byte, 256)
+	for i := range data {
+		data[i] = byte(i)
+	}
+	badChars := data // all 256 values are "bad"
+
+	if _, err := FindXORKey(data, badChars); err == nil {
+		t.Error("expected an error when every byte value is both present and forbidden")
+	}
+}