feat: migrate TOTP secrets to keying

- Currently the TOTP secrets are stored using the `secrets` module with
as key the MD5 hash of the Secretkey, the `secrets` module uses general
bad practices. This patch migrates the secrets to use the `keying`
module (#5041) which is easier to use and use better practices to store
secrets in databases.
- Migration test added.
- Remove the Forgejo migration databases, and let the gitea migration
databases also run forgejo migration databases. This is required as the
Forgejo migration is now also touching tables that the forgejo migration
didn't create itself.

models/auth/twofactor.go

@@ -5,17 +5,14 @@ package auth
 
 import (
 	"context"
-	"crypto/md5"
 	"crypto/sha256"
 	"crypto/subtle"
 	"encoding/base32"
-	"encoding/base64"
 	"encoding/hex"
 	"fmt"
 
 	"code.gitea.io/gitea/models/db"
-	"code.gitea.io/gitea/modules/secret"
-	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/keying"
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/util"
 
@@ -49,9 +46,9 @@ func (err ErrTwoFactorNotEnrolled) Unwrap() error {
 
 // TwoFactor represents a two-factor authentication token.
 type TwoFactor struct {
-	ID               int64 `xorm:"pk autoincr"`
-	UID              int64 `xorm:"UNIQUE"`
-	Secret           string
+	ID               int64  `xorm:"pk autoincr"`
+	UID              int64  `xorm:"UNIQUE"`
+	Secret           []byte `xorm:"BLOB"`
 	ScratchSalt      string
 	ScratchHash      string
 	LastUsedPasscode string             `xorm:"VARCHAR(10)"`
@@ -92,39 +89,35 @@ func (t *TwoFactor) VerifyScratchToken(token string) bool {
 	return subtle.ConstantTimeCompare([]byte(t.ScratchHash), []byte(tempHash)) == 1
 }
 
-func (t *TwoFactor) getEncryptionKey() []byte {
-	k := md5.Sum([]byte(setting.SecretKey))
-	return k[:]
-}
-
 // SetSecret sets the 2FA secret.
-func (t *TwoFactor) SetSecret(secretString string) error {
-	secretBytes, err := secret.AesEncrypt(t.getEncryptionKey(), []byte(secretString))
-	if err != nil {
-		return err
-	}
-	t.Secret = base64.StdEncoding.EncodeToString(secretBytes)
-	return nil
+func (t *TwoFactor) SetSecret(secretString string) {
+	key := keying.DeriveKey(keying.ContextTOTP)
+	t.Secret = key.Encrypt([]byte(secretString), keying.ColumnAndID("secret", t.ID))
 }
 
 // ValidateTOTP validates the provided passcode.
 func (t *TwoFactor) ValidateTOTP(passcode string) (bool, error) {
-	decodedStoredSecret, err := base64.StdEncoding.DecodeString(t.Secret)
+	key := keying.DeriveKey(keying.ContextTOTP)
+	secret, err := key.Decrypt(t.Secret, keying.ColumnAndID("secret", t.ID))
 	if err != nil {
 		return false, err
 	}
-	secretBytes, err := secret.AesDecrypt(t.getEncryptionKey(), decodedStoredSecret)
-	if err != nil {
-		return false, err
-	}
-	secretStr := string(secretBytes)
-	return totp.Validate(passcode, secretStr), nil
+	return totp.Validate(passcode, string(secret)), nil
 }
 
 // NewTwoFactor creates a new two-factor authentication token.
-func NewTwoFactor(ctx context.Context, t *TwoFactor) error {
-	_, err := db.GetEngine(ctx).Insert(t)
-	return err
+func NewTwoFactor(ctx context.Context, t *TwoFactor, secret string) error {
+	return db.WithTx(ctx, func(ctx context.Context) error {
+		sess := db.GetEngine(ctx)
+		_, err := sess.Insert(t)
+		if err != nil {
+			return err
+		}
+
+		t.SetSecret(secret)
+		_, err = sess.Cols("secret").ID(t.ID).Update(t)
+		return err
+	})
 }
 
 // UpdateTwoFactor updates a two-factor authentication token.