cryptutil: add streaming crypt helpers

pkg/cryptutil/stream_test.go

@@ -0,0 +1,39 @@
+package cryptutil_test
+
+import (
+	"bytes"
+	"crypto/rand"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/pomerium/pomerium/pkg/cryptutil"
+)
+
+func TestEncryptStream(t *testing.T) {
+	t.Parallel()
+
+	plaintext := make([]byte, 4048*2.5)
+	_, err := rand.Read(plaintext)
+	require.NoError(t, err)
+
+	// cipher
+	c, err := cryptutil.NewAEADCipher(cryptutil.NewKey())
+	require.NoError(t, err)
+
+	// encrypt
+	encrypted := &bytes.Buffer{}
+	encrypter, err := cryptutil.EncryptStream(bytes.NewBuffer(plaintext), c)
+	require.NoError(t, err)
+	_, err = io.Copy(encrypted, encrypter)
+	require.NoError(t, err)
+
+	// decrypt
+	decrypted := &bytes.Buffer{}
+	decrypter, err := cryptutil.DecryptStream(encrypted, c)
+	require.NoError(t, err)
+	_, err = decrypted.ReadFrom(decrypter)
+	require.NoError(t, err)
+	require.Equal(t, plaintext, decrypted.Bytes())
+}