Add data encryption / decryption utilities

data/data_test.go

@@ -0,0 +1,70 @@
+// Package data provides utilities for interacting with database data
+// throughout Write.as.
+package data
+
+import (
+	"bytes"
+	"crypto/rand"
+	"strings"
+	"testing"
+)
+
+func TestEncDec(t *testing.T) {
+	// Generate a random key with a valid length
+	k := make([]byte, keyLen)
+	_, err := rand.Read(k)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	runEncDec(t, k, "this is my secret message™. 😄", nil)
+	runEncDec(t, k, "mygreatemailaddress@gmail.com", nil)
+}
+
+func TestAuthentication(t *testing.T) {
+	// Generate a random key with a valid length
+	k := make([]byte, keyLen)
+	_, err := rand.Read(k)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	runEncDec(t, k, "mygreatemailaddress@gmail.com", func(c []byte) []byte {
+		c[0] = 'a'
+		t.Logf("Modified:   %s\n", c)
+		return c
+	})
+}
+
+func runEncDec(t *testing.T, k []byte, plaintext string, transform func([]byte) []byte) {
+	t.Logf("Plaintext:  %s\n", plaintext)
+
+	// Encrypt the data
+	ciphertext, err := Encrypt(k, plaintext)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Logf("Ciphertext: %s\n", ciphertext)
+
+	if transform != nil {
+		ciphertext = transform(ciphertext)
+	}
+
+	// Decrypt the data
+	decryptedText, err := Decrypt(k, ciphertext)
+	if err != nil {
+		if transform != nil && strings.Contains(err.Error(), "message authentication failed") {
+			// We modified the ciphertext; make sure we're getting the right error
+			t.Logf("%v\n", err)
+			return
+		}
+		t.Fatal(err)
+	}
+
+	t.Logf("Decrypted:  %s\n", string(decryptedText))
+
+	if !bytes.Equal([]byte(plaintext), decryptedText) {
+		t.Errorf("Plaintext mismatch: got %x vs %x", plaintext, decryptedText)
+	}
+}