增加iv校验 (#482)

miniprogram/encryptor/encryptor.go

@@ -6,6 +6,7 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"errors"
+	"fmt"
 
 	"github.com/silenceper/wechat/v2/miniprogram/context"
 )
@@ -90,6 +91,9 @@ func GetCipherText(sessionKey, encryptedData, iv string) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+	if len(ivBytes) != aes.BlockSize {
+		return nil, fmt.Errorf("bad iv length %d", len(ivBytes))
+	}
 	block, err := aes.NewCipher(aesKey)
 	if err != nil {
 		return nil, err