diff --git a/Readme.md b/Readme.md
index 2365453..9b2c81f 100644
--- a/Readme.md
+++ b/Readme.md
@@ -252,7 +252,7 @@ crypto.hmac('md5', '123456', 'sdfvkjfhd')
 #### cipher(mode, data[, key, inEncode, outEncode])
 - mode `<String>`
 - data `<String>` | `<Buffer>`
-- key `<String>` 可选, 默认为 `<Buffer d7 2c 87 d0 f0 77 c7 76 6f 29 85 df ab 30 e8 95>`, 即 `crypto.scryptSync('', '', 16)` 的结果
+- key `<String>` 可选, 默认为 `<Buffer 0 0 0 ... 0>`, 即 `Buffer.alloc(16)` 的结果
 - inEncode '<String>' 可选
 - outEncode '<String>' 可选，默认返回Buffer对象