diff --git a/.gitignore b/.gitignore
index 46dd5c4..d7e9ceb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@ package-lock.json
 .svn
 ~*
 .gitattributes
+dump.rdb
diff --git a/dump.rdb b/dump.rdb
deleted file mode 100644
index 54b7200..0000000
Binary files a/dump.rdb and /dev/null differ
diff --git a/index.js b/index.js
index 76be726..a831062 100644
--- a/index.js
+++ b/index.js
@@ -67,7 +67,10 @@ module.exports = {
   }
   ,
   isSecword(secword){
-    return Secword.isValid(secword)
+    if (typeof secword==='string' && 12===secword.split(/ +/))
+      return Secword.isValid(secword)
+    else
+      return false
   }
   ,
   isSeckey(seckey){
@@ -357,7 +360,7 @@ module.exports = {
         case 'devnet': prefix='74'; break; // Base58: 0x90 => d, Base 64: d=0x1d=0b00011101 => 0b 011101xx = 0x74~77
         default: prefix='4c'
       }
-      let checksum = this.hash(this.hash(position)).slice(0,6) // 添加 checksum 使得能够检测大小写错误。注意，不包含 prefix，这样更纯粹、专注。
+      let checksum = this.hash(this.hash(prefix+position)).slice(0,6) // 添加 checksum 使得能够检测大小写错误。[todo] 校验码里要不要包含 prefix?
 //      address = this.hex2eip55(prefix + position + checksum) // 前缀1节，位置20节，校验3节，共24节=48字符（能够完全转化为8个色彩），再转eip55。
       address = this.hex2b64u(prefix + position + checksum) // 实际采用 b64u (named by luk.lu as base 64 for url), 共 32字符。
       return address
@@ -384,16 +387,17 @@ module.exports = {
   }
   ,
   isAddress(address){
-    if (/^0x[\da-fA-F]{40}$/.test(address)){
+    if (/^(0x)?[\da-fA-F]{40}$/.test(address)){
       return 'ETH'
-    }else if (/^[123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz]{26,34}$/.test(address) // 格式合法
-      && this.b58c2hex(address)){ // 内容合法
+    }else if (/^[123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz]{26,34}$/.test(address)){ // 格式合法
+      let prefixedPosition = this.b58c2hex(address)
+      if (prefixedPosition && prefixedPosition.length===42) // 内容合法
       return 'BTC'
     }else if (/^[Ttd][0-9a-zA-Z\-_]{31}$/.test(address)){ // 格式合法
       let b64 = address.replace('-', '+').replace('_', '/')
       let hex = Buffer.from(b64, 'base64').toString('hex')
-      let [all, prefix, position, checksum] = hex.match(/^([\da-fA-F]{2})([\da-fA-F]{40})([\da-fA-F]{6})$/)
-      return this.hash(this.hash(position)).slice(0,6) === checksum
+      let [all, prefix, position, checksum] = hex.match(/^([\da-fA-F]{2})([\da-fA-F]{40})([\da-fA-F]{6})$/) // 内容合法
+      return this.hash(this.hash(prefix+position)).slice(0,6) === checksum // [todo] 校验码里要不要包含 prefix?
     }
     return null
   }