diff --git a/index.js b/index.js
index f742f94..82d1537 100644
--- a/index.js
+++ b/index.js
@@ -1,6 +1,7 @@
 var pbkdf2 = require('pbkdf2');
 var createHmac = require('create-hmac');
 var Promise = require("bluebird");
+var v2 = require('./src/v2');
 
 module.exports = {
     encryptLogin: _encryptLogin,
@@ -12,7 +13,8 @@ module.exports = {
     _string2charCodes: _string2charCodes,
     _getCharType: _getCharType,
     _getPasswordChar: _getPasswordChar,
-    _createHmac: _createHmac
+    _createHmac: _createHmac,
+    _calcEntropy: v2.calcEntropy
 };
 
 function _encryptLogin(login, masterPassword, options) {
diff --git a/package.json b/package.json
index 46763ea..1cc8b70 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,7 @@
   "scripts": {
     "build": "rimraf lib && mkdir lib && browserify --standalone LessPass index.js > lib/lesspass.js && gulp",
     "prepublish": "npm test && npm run build && npm run test:node && npm run test:browser",
-    "test": "mocha --require ./tests/helper.js tests",
+    "test": "mocha --require ./tests/helper.js tests/*",
     "test:node": "npm run build && cd tests && node node.js && cd ..",
     "test:webcrypto": "karma start tests/karma.webcrypto.config.js",
     "test:browser": "npm run build && karma start tests/karma.config.js"
diff --git a/src/v2.js b/src/v2.js
new file mode 100644
index 0000000..13c59cc
--- /dev/null
+++ b/src/v2.js
@@ -0,0 +1,18 @@
+var Promise = require("bluebird");
+var pbkdf2 = require('pbkdf2');
+
+exports.calcEntropy = function (site, login, masterPassword, passwordProfile) {
+    return new Promise(function (resolve, reject) {
+        var salt = site + login + passwordProfile.counter.toString(16);
+        var iterations = passwordProfile.iterations || 100000;
+        var keylen = passwordProfile.keylen || 32;
+        var digest = passwordProfile.digest || 'sha256';
+        pbkdf2.pbkdf2(masterPassword, salt, iterations, keylen, digest, function (error, key) {
+            if (error) {
+                reject('error in pbkdf2');
+            } else {
+                resolve(key.toString('hex'));
+            }
+        });
+    })
+};
\ No newline at end of file
diff --git a/tests/v2/entropy.tests.js b/tests/v2/entropy.tests.js
new file mode 100644
index 0000000..80897f0
--- /dev/null
+++ b/tests/v2/entropy.tests.js
@@ -0,0 +1,53 @@
+var assert = chai.assert;
+
+describe('LessPass', function () {
+    describe('entropy', function () {
+        it('calc entropy pbkdf2 with default params (100000 iterations, 32 bytes length, sha256 digest)', function () {
+            this.timeout(10000);
+            var site = 'example.org';
+            var login = 'contact@example.org';
+            var masterPassword = 'password';
+            var passwordProfile = {
+                counter: 1
+            };
+            return LessPass._calcEntropy(site, login, masterPassword, passwordProfile).then(function (entropy) {
+                assert.equal('dc33d431bce2b01182c613382483ccdb0e2f66482cbba5e9d07dab34acc7eb1e', entropy);
+            })
+        });
+
+        it('calc entropy with different options (8192 iterations, 16 bytes length, sha512 digest)', function () {
+            var site = 'example.org';
+            var login = 'contact@example.org';
+            var masterPassword = 'password';
+            var passwordProfile = {
+                iterations: 8192,
+                keylen: 16,
+                digest: 'sha512',
+                counter: 1
+            };
+            return LessPass._calcEntropy(site, login, masterPassword, passwordProfile).then(function (entropy) {
+                assert.equal('fff211c16a4e776b3574c6a5c91fd252', entropy);
+            })
+        });
+
+        it('calc entropy different if counter different', function () {
+            var site = 'example.org';
+            var login = 'contact@example.org';
+            var masterPassword = 'password';
+            var passwordProfile1 = {
+                iterations: 1,
+                counter: 1
+            };
+            var passwordProfile2 = {
+                iterations: 1,
+                counter: 2
+            };
+            var p1 = LessPass._calcEntropy(site, login, masterPassword, passwordProfile1);
+            var p2 = LessPass._calcEntropy(site, login, masterPassword, passwordProfile2);
+            return Promise.all([p1, p2]).then(function (entropies) {
+                assert.notEqual(entropies[0], entropies[1])
+            });
+        });
+
+    });
+});
\ No newline at end of file