2 files changed, 102 insertions, 4 deletions

diff --git a/pkg/service/auth.go b/pkg/service/auth.go
index 761c70b..1966e70 100644
--- a/pkg/service/auth.go
+++ b/pkg/service/auth.go
@@ -1,12 +1,18 @@
 package service
 
 import (
+	"bytes"
 	"context"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/gob"
+	"errors"
+	"io"
 
 	"golang.org/x/crypto/bcrypt"
 
 	"git.sr.ht/~gabrielgio/img/pkg/database/repository"
-	"git.sr.ht/~gabrielgio/img/pkg/ext"
 )
 
 type AuthController struct {
@@ -42,11 +48,11 @@ func (c *AuthController) Login(ctx context.Context, username, password []byte) (
 		return nil, err
 	}
 
-	token := &ext.Token{
+	token := &Token{
 		UserID:   id,
 		Username: string(username),
 	}
-	return ext.WriteToken(token, c.key)
+	return WriteToken(token, c.key)
 }
 
 // InitialRegister register a initial user, it will validate if there is another
@@ -75,3 +81,64 @@ func (c *AuthController) InitialRegister(ctx context.Context, username, password
 
 	return err
 }
+
+type Token struct {
+	UserID   uint
+	Username string
+}
+
+func ReadToken(data []byte, key []byte) (*Token, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		panic(err.Error())
+	}
+
+	nonceSize := aesgcm.NonceSize()
+	if len(data) < nonceSize {
+		return nil, errors.New("nonce size greater than data's size")
+	}
+
+	nonce, ciphertext := data[:nonceSize], data[nonceSize:]
+	plaintext, err := aesgcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	r := bytes.NewReader(plaintext)
+	var token Token
+	dec := gob.NewDecoder(r)
+	if err = dec.Decode(&token); err != nil {
+		return nil, err
+	}
+	return &token, nil
+}
+
+func WriteToken(token *Token, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	var buffer bytes.Buffer
+	enc := gob.NewEncoder(&buffer)
+	if err := enc.Encode(token); err != nil {
+		return nil, err
+	}
+	nonce := make([]byte, aesgcm.NonceSize())
+	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+
+	ciphertext := aesgcm.Seal(nonce, nonce, buffer.Bytes(), nil)
+	return ciphertext, nil
+}
diff --git a/pkg/service/auth_test.go b/pkg/service/auth_test.go
index 35b2475..7083d0c 100644
--- a/pkg/service/auth_test.go
+++ b/pkg/service/auth_test.go
@@ -64,7 +64,7 @@ func TestInitialRegisterAndLogin(t *testing.T) {
 			auth, err := scene.controller.Login(scene.ctx, []byte(tc.username), tc.password)
 			testkit.TestFatalError(t, "Login", err)
 
-			token, err := ext.ReadToken(auth, key)
+			token, err := ReadToken(auth, key)
 			testkit.TestFatalError(t, "Login", err)
 
 			testkit.TestValue(t, "Login", tc.username, token.Username)
@@ -76,3 +76,34 @@ func TestInitialRegisterAndLogin(t *testing.T) {
 func remove[T any](slice []T, s int) []T {
 	return append(slice[:s], slice[s+1:]...)
 }
+
+func TestReadWriteToken(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name  string
+		key   []byte
+		token *Token
+	}{
+		{
+			name: "Normal write",
+			key:  []byte("AES256Key-32Characters1234567890"),
+			token: &Token{
+				UserID:   3,
+				Username: "username",
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			data, err := WriteToken(tc.token, tc.key)
+			testkit.TestFatalError(t, "WriteToken", err)
+
+			token, err := ReadToken(data, tc.key)
+			testkit.TestFatalError(t, "ReadToken", err)
+
+			testkit.TestValue(t, "ReadWriteToken", token, tc.token)
+		})
+	}
+}