Encryption: Extract encryption into service (#38442)

* Add encryption service

* Add tests for encryption service

* Inject encryption service into http server

* Replace encryption global function usage in login tests

* Apply suggestions from code review

Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>

* Migrate to Wire

* Undo non-desired changes

* Move Encryption bindings to OSS Wire set

Co-authored-by: Joan López de la Franca Beltran <joanjan14@gmail.com>
Co-authored-by: Joan López de la Franca Beltran <5459617+joanlopez@users.noreply.github.com>
Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>

pkg/services/encryption/ossencryption/ossencryption_test.go

@@ -0,0 +1,39 @@
+package ossencryption
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEncryption(t *testing.T) {
+	svc := Service{}
+
+	t.Run("getting encryption key", func(t *testing.T) {
+		key, err := encryptionKeyToBytes("secret", "salt")
+		require.NoError(t, err)
+		assert.Len(t, key, 32)
+
+		key, err = encryptionKeyToBytes("a very long secret key that is larger then 32bytes", "salt")
+		require.NoError(t, err)
+		assert.Len(t, key, 32)
+	})
+
+	t.Run("decrypting basic payload", func(t *testing.T) {
+		encrypted, err := svc.Encrypt([]byte("grafana"), "1234")
+		require.NoError(t, err)
+
+		decrypted, err := svc.Decrypt(encrypted, "1234")
+		require.NoError(t, err)
+
+		assert.Equal(t, []byte("grafana"), decrypted)
+	})
+
+	t.Run("decrypting empty payload should return error", func(t *testing.T) {
+		_, err := svc.Decrypt([]byte(""), "1234")
+		require.Error(t, err)
+
+		assert.Equal(t, "unable to compute salt", err.Error())
+	})
+}