diff --git a/index.js b/index.js
index debe651..fd9c42e 100644
--- a/index.js
+++ b/index.js
@@ -107,13 +107,13 @@ module.exports = {
       if (this.isHashable(data) && typeof(key)==='string') {
         let inputEncoding=my.INPUT_LIST.indexOf(input)>=0?input:my.INPUT // 'utf8' by default, 'ascii', 'latin1' for string  or ignored for Buffer/TypedArray/DataView
         let outputEncoding=(output==='buf')?undefined:(my.OUTPUT_LIST.indexOf(output)>=0?output:my.OUTPUT) // 'latin1', 'base64', 'hex' by default or 'buf' to Buffer explicitly
-        let cipher=crypto.createCipher(
+        let ciph=crypto.createCipher(
           my.CIPHER_LIST.indexOf(cipher)>=0?cipher:my.CIPHER, 
           this.hash(key))
         if (typeof(data)!=='string' && !(data instanceof Buffer) && !(data instanceof DataView)) 
           data=JSON.stringify(data)
-        let encrypted = cipher.update(data, inputEncoding, outputEncoding)
-        encrypted += cipher.final(outputEncoding) // 但是 Buffer + Buffer 还是会变成string
+        let encrypted = ciph.update(data, inputEncoding, outputEncoding)
+        encrypted += ciph.final(outputEncoding) // 但是 Buffer + Buffer 还是会变成string
         return encrypted
       }
     }else if (keytype==='pubkey') {  // data 应当是 utf8 的字符串。// 但在浏览器里不能使用 Failed to execute 'encrypt' on 'SubtleCrypto': The provided value is not of type '(ArrayBuffer or ArrayBufferView)'
@@ -141,9 +141,13 @@ module.exports = {
           }
         }
         return decrypted
-      }else if (keytype==='seckey'){ // cipherobject 需要是 eccrypto 自身encrypt方法返回的对象
+      }
+    }else if (keytype==='seckey'){ // cipherobject 需要是 eccrypto 自身encrypt方法返回的对象
+      try {
         let plaindata = await eccrypto.decrypt(Buffer.from(key, 'hex'), data) // eccrypto 需要调用 Buffer.compare 方法，不能在这里直接用 hex2buf
         return plaindata.toString('utf8')
+      }catch (exception){ // eccrypto 对无法解密的，会抛出异常
+        return null
       }
     }
     return null
@@ -192,10 +196,11 @@ module.exports = {
         try {
           let result = await eccrypto.verify(Buffer.from(pubkey, 'hex'), this.hash(data, {output:'buf'}), Buffer.from(signature, 'hex')) // 如果给signature添加1位hex，eccrypto 的 verify结果也是true! 估计因为一位hex不被转成字节。
           return true
-        }catch(exception){
+        }catch(exception){ // 对能够验证的，eccrypto返回 null；对无法验证的，抛出异常
           return false
         }
       }
+      return false
     }
     if (this.isHashable(data) && this.isSignature(signature) && this.isPubkey(pubkey) && signature.length===128){ // nacl
       option.output='buf' // 哈希必须输出为 buffer
@@ -284,6 +289,24 @@ module.exports = {
     return null
   }
   ,
+  seed2path(seed, {coin='TIC'}={coin:'TIC'}){
+    // 路径规范 BIP44: m/Purpose'/Coin'/Account'/Change/Index,
+    // 但实际上 Purpose, Coin 都可任意定；' 可有可无；
+    // Account 最大到 parseInt(0x7FFFFFFF, 16), Coin/Index最大到 parseInt(0xFFFFFFFF, 16)
+    // 后面还可继续延伸 /xxx/xxx/xxx/......    let hash=this.hash(seed, {hasher:'md5'})
+    let part0=parseInt(hash.slice(0,6), 16)
+    let part1=parseInt(hash.slice(6,12), 16)
+    let part2=parseInt(hash.slice(12,18), 16)
+    let part3=parseInt(hash.slice(18,24), 16)
+    let part4=parseInt(hash.slice(24,32), 16)
+    switch (coin){
+      case 'BTC': return `m/44'/0'/${part0}'/${part1}/${part2}/${part3}/${part4}`
+      case 'ETH': return `m/44'/60'/${part0}'/${part1}/${part2}/${part3}/${part4}`
+      case 'TIC': 
+      default: return `m/44'/66'/${part0}'/${part1}/${part2}/${part3}/${part4}`
+    }
+  }
+  ,
   secword2account(secword, option){ // account 比 keypair 多了 address 字段。
     option=option||{}
     option.coin=my.COIN_LIST.indexOf(option.coin)>=0?option.coin:my.COIN
@@ -552,11 +575,9 @@ module.exports = {
   }
   ,
   padStart(string, targetLength, symbol){ // 2020-03: 发现在浏览器里，还不支持 string.padStart()，只好自己写个暂代。
-    let stringLength = string.length
-    if (stringLength < targetLength) {
-      for (let index = 1; index <= targetLength-stringLength; index++) {
-        string = symbol + string
-      }
+    let padLength = targetLength - string.length
+    for (let index = 1; index <= padLength; index++) {
+      string = symbol + string
     }
     return string
   }