0904

internal/db/password.go

@@ -0,0 +1,85 @@
+package db
+
+import (
+	"crypto/subtle"
+	"encoding/hex"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+	"github.com/wuhan005/gadget"
+	"golang.org/x/crypto/bcrypt"
+
+	"github.com/tamakyi/TamaBox/internal/conf"
+)
+
+// bcryptCost is the cost parameter for bcrypt (10 is a good default, 12 for higher security).
+const bcryptCost = 10
+
+// bcryptMaxPasswordLen is the effective input length of bcrypt (72 bytes).
+// bcrypt 只使用前 72 字节；新版 x/crypto 对超长密码直接返回错误，
+// 这里统一截断到 72 字节（与 bcrypt 原生语义一致），避免走错误分支。
+const bcryptMaxPasswordLen = 72
+
+// encodePasswordBcrypt hashes a password with bcrypt.
+// 注意：失败时绝不能静默降级为 HMAC-SHA1 弱哈希（此前行为），
+// 返回空串会让该账号所有密码校验失败并留下错误日志，比弱哈希更安全。
+func encodePasswordBcrypt(password string) string {
+	if len(password) > bcryptMaxPasswordLen {
+		password = password[:bcryptMaxPasswordLen]
+	}
+	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcryptCost)
+	if err != nil {
+		// cost 为常量 10，正常不会到这里；防御性记录，不降级为弱哈希。
+		logrus.WithError(err).Error("bcrypt generate failed")
+		return ""
+	}
+	return string(hash)
+}
+
+// isBcryptHash checks if the given string is a bcrypt hash.
+func isBcryptHash(hash string) bool {
+	return strings.HasPrefix(hash, "$2a$") || strings.HasPrefix(hash, "$2b$") || strings.HasPrefix(hash, "$2y$")
+}
+
+// IsBcryptHash exported for use in other packages.
+func IsBcryptHash(hash string) bool {
+	return isBcryptHash(hash)
+}
+
+// authenticatePassword verifies a password against either bcrypt or legacy HMAC-SHA1 hash.
+// Returns (true, newHash) if the password matches. If the old HMAC-SHA1 format was used,
+// newHash contains the upgraded bcrypt hash — caller should persist it.
+func authenticatePassword(storedHash, password string) (bool, string) {
+	if storedHash == "" {
+		return false, ""
+	}
+
+	// Try bcrypt first (new format).
+	if isBcryptHash(storedHash) {
+		err := bcrypt.CompareHashAndPassword([]byte(storedHash), []byte(password))
+		return err == nil, ""
+	}
+
+	// Fall back to legacy HMAC-SHA1（常量时间比较，防时序侧信道）。
+	legacyHash := gadget.HmacSha1(password, conf.Server.Salt)
+	if subtle.ConstantTimeCompare([]byte(legacyHash), []byte(storedHash)) == 1 {
+		// Password matches legacy format — upgrade to bcrypt.
+		return true, encodePasswordBcrypt(password)
+	}
+
+	return false, ""
+}
+
+// needsRehash checks if a bcrypt hash should be rehashed (e.g., cost changed).
+func needsRehash(hash string) bool {
+	cost, err := bcrypt.Cost([]byte(hash))
+	if err != nil {
+		return true
+	}
+	return cost != bcryptCost
+}
+
+// HexEncodeToString is a helper to encode bytes as hex for legacy hash comparison.
+func HexEncodeToString(src []byte) string {
+	return hex.EncodeToString(src)
+}