Encrypt passwords in DB (#1187)

* Encode/Encrypt passwords in DB

* Only decrypts passwords if it is necessary

* Add tests for encryption functions

utils/encrypt.go

@@ -0,0 +1,64 @@
+package utils
+
+import (
+	"context"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"io"
+
+	"github.com/navidrome/navidrome/log"
+)
+
+func Encrypt(ctx context.Context, encKey []byte, data string) (string, error) {
+	plaintext := []byte(data)
+
+	block, err := aes.NewCipher(encKey)
+	if err != nil {
+		log.Error(ctx, "Could not create a cipher", err)
+		return "", err
+	}
+
+	aesGCM, err := cipher.NewGCM(block)
+	if err != nil {
+		log.Error(ctx, "Could not create a GCM", "user", err)
+		return "", err
+	}
+
+	nonce := make([]byte, aesGCM.NonceSize())
+	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
+		log.Error(ctx, "Could generate nonce", err)
+		return "", err
+	}
+
+	ciphertext := aesGCM.Seal(nonce, nonce, plaintext, nil)
+	return base64.StdEncoding.EncodeToString(ciphertext), nil
+}
+
+func Decrypt(ctx context.Context, encKey []byte, encData string) (string, error) {
+	enc, _ := base64.StdEncoding.DecodeString(encData)
+
+	block, err := aes.NewCipher(encKey)
+	if err != nil {
+		log.Error(ctx, "Could not create a cipher", err)
+		return "", err
+	}
+
+	aesGCM, err := cipher.NewGCM(block)
+	if err != nil {
+		log.Error(ctx, "Could not create a GCM", err)
+		return "", err
+	}
+
+	nonceSize := aesGCM.NonceSize()
+	nonce, ciphertext := enc[:nonceSize], enc[nonceSize:]
+
+	plaintext, err := aesGCM.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		log.Error(ctx, "Could not decrypt password", err)
+		return "", err
+	}
+
+	return string(plaintext), nil
+}

utils/encrypt_test.go

@@ -0,0 +1,38 @@
+package utils
+
+import (
+	"context"
+	"crypto/sha256"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("encrypt", func() {
+	It("decrypts correctly when using the same encryption key", func() {
+		sum := sha256.Sum256([]byte("password"))
+		encKey := sum[0:]
+		data := "Can you keep a secret?"
+
+		encrypted, err := Encrypt(context.Background(), encKey, data)
+		Expect(err).ToNot(HaveOccurred())
+		decrypted, err := Decrypt(context.Background(), encKey, encrypted)
+		Expect(err).ToNot(HaveOccurred())
+
+		Expect(decrypted).To(Equal(data))
+	})
+
+	It("fails to decrypt if not using the same encryption key", func() {
+		sum := sha256.Sum256([]byte("password"))
+		encKey := sum[0:]
+		data := "Can you keep a secret?"
+
+		encrypted, err := Encrypt(context.Background(), encKey, data)
+		Expect(err).ToNot(HaveOccurred())
+
+		sum = sha256.Sum256([]byte("different password"))
+		encKey = sum[0:]
+		_, err = Decrypt(context.Background(), encKey, encrypted)
+		Expect(err).To(MatchError("cipher: message authentication failed"))
+	})
+})