evp: simplify overall logic

EVP_BytesToKey.js

@@ -1,39 +1,35 @@
-var createHash = require('create-hash');
-module.exports = function evp(password, salt, keyLen) {
-  keyLen = keyLen/8;
-  var ki = 0;
-  var ii = 0;
-  var key = new Buffer(keyLen);
-  var addmd = 0;
-  var md, md_buf;
-  var i;
-  while (true) {
-    md = createHash('md5');
-    if(addmd++ > 0) {
-       md.update(md_buf);
+var createHash = require('create-hash')
+
+module.exports = function evp (password, salt, keyLen) {
+  keyLen = keyLen / 8
+
+  var offset = 0
+  var key = new Buffer(keyLen)
+  var buffer
+
+  while (keyLen > 0) {
+    var hash = createHash('md5')
+
+    if (buffer) {
+      hash.update(buffer)
     }
-    md.update(password);
-    md.update(salt);
-    md_buf = md.digest();
-    i = 0;
-    if(keyLen > 0) {
-      while(true) {
-        if(keyLen === 0) {
-          break;
-        }
-        if(i === md_buf.length) {
-          break;
-        }
-        key[ki++] = md_buf[i++];
-        keyLen--;
-       }
+
+    hash.update(password)
+    hash.update(salt)
+    buffer = hash.digest()
+
+    for (var i = 0; i < buffer.length; ++i) {
+      if (keyLen === 0) break
+
+      key[offset] = buffer[i]
+
+      keyLen--
+      offset++
     }
-   if(keyLen === 0) {
-      break;
-    }
-  }
-  for(i=0;i<md_buf.length;i++) {
-    md_buf[i] = 0;
   }
-  return key;
-};
+
+  // zero the temporary buffer
+  buffer.fill(0)
+
+  return key
+}