feat: sign of file

pkg/sign/hmac.go

@@ -0,0 +1,52 @@
+package sign
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"io"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type HMACSign struct {
+	SecretKey []byte
+}
+
+func (s HMACSign) Sign(data string, expire int64) string {
+	h := hmac.New(sha256.New, s.SecretKey)
+	expireTimeStamp := strconv.FormatInt(expire, 10)
+	_, err := io.WriteString(h, data+":"+expireTimeStamp)
+	if err != nil {
+		return ""
+	}
+
+	return base64.URLEncoding.EncodeToString(h.Sum(nil)) + ":" + expireTimeStamp
+}
+
+func (s HMACSign) Verify(data, sign string) error {
+	signSlice := strings.Split(sign, ":")
+	// check whether contains expire time
+	if signSlice[len(signSlice)-1] == "" {
+		return ErrExpireMissing
+	}
+	// check whether expire time is expired
+	expires, err := strconv.ParseInt(signSlice[len(signSlice)-1], 10, 64)
+	if err != nil {
+		return ErrExpireInvalid
+	}
+	// if expire time is expired, return error
+	if expires < time.Now().Unix() && expires != 0 {
+		return ErrSignExpired
+	}
+	// verify sign
+	if s.Sign(data, expires) != sign {
+		return ErrSignInvalid
+	}
+	return nil
+}
+
+func NewHMACSign(secret []byte) Sign {
+	return HMACSign{SecretKey: secret}
+}