user606521 user606521 - 2 months ago 9
ASP.NET (C#) Question

How to check ASP.NET password hash in node.js

First of all I read this Hashing a password using SHA256 and .NET/Node.js and it didn't help me.

I have to verify passwords hashes created in ASP.NET in node.js environment. I was told that passwords are generated using this algorithm: What is default hash algorithm that ASP.NET membership uses?.

I have example password hash and salt (first line is password and second line is salt):

"Password": "jj/rf7OxXM263rPgvLan4M6Is7o=",
"PasswordSalt": "/Eju9rmaJp03e3+z1v5s+A==",


I know that hash algorithm is
SHA1
and I know that above hash is generated for input
test123
. However I can't reproduce hashing algorithm to get same hash for this input. What I tried:

Password = "jj/rf7OxXM263rPgvLan4M6Is7o="
PasswordSalt = "/Eju9rmaJp03e3+z1v5s+A=="
crypto = require("crypto")
sha1 = crypto.createHash("sha1")
PasswordSalt = new Buffer(PasswordSalt, 'base64').toString('utf8')
sha1.update(PasswordSalt+"test123", "utf8")
result = sha1.digest("base64")
console.log(Password)
console.log(result)


Result is:

jj/rf7OxXM263rPgvLan4M6Is7o=
xIjxRod4+HVYzlHZ9xomGGGY6d8=





I was able to get working C# algorithm:

using System.IO;
using System;
using System.Text;
using System.Security.Cryptography;

class Program
{

static string EncodePassword(string pass, string salt)
{
byte[] bytes = Encoding.Unicode.GetBytes(pass);
byte[] src = Convert.FromBase64String(salt);
byte[] dst = new byte[src.Length + bytes.Length];
Buffer.BlockCopy(src, 0, dst, 0, src.Length);
Buffer.BlockCopy(bytes, 0, dst, src.Length, bytes.Length);
HashAlgorithm algorithm = HashAlgorithm.Create("SHA1");
byte[] inArray = algorithm.ComputeHash(dst);
return Convert.ToBase64String(inArray);
}

static void Main()
{
string pass = "test123";
string salt = "/Eju9rmaJp03e3+z1v5s+A==";
string hash = Program.EncodePassword(pass,salt);
Console.WriteLine(hash);
// outputs jj/rf7OxXM263rPgvLan4M6Is7o=
}
}


So now it is just a matter of porting this algorithm to node.js. The problem is that c# somehow magically operates on bytes and I don't know how to do it in node. Consider following code (it does not use any salt - it just creates base64 sha1 from password:

crypto = require("crypto")
pass = 'test123'
sha1 = crypto.createHash("sha1")
buf = new Buffer( pass, 'utf8')
sha1.update(buf)
result = sha1.digest("base64")
console.log(result)
// outputs cojt0Pw//L6ToM8G41aOKFIWh7w=


And in c#

using System.Text;
using System.Security.Cryptography;
string pass = "test123";
byte[] bytes = Encoding.Unicode.GetBytes(pass);
HashAlgorithm algorithm = HashAlgorithm.Create("SHA1");
byte[] inArray = algorithm.ComputeHash(bytes);
string hash = Convert.ToBase64String(inArray);
Console.WriteLine(hash);
// outputs Oc/baVMs/zM28IqDqsQlJPQc1uk=


I need code in node.js that will return same value as code in c#. Any ideas?

Answer

I finally found the right answer here: https://gist.github.com/PalmerEk/1191651 (with little change from 'ucs2' to 'utf16le'):

function dotnet_membership_password_hash(pass, salt)
{
  var bytes = new Buffer(pass || '', 'utf16le');
  var src = new Buffer(salt || '', 'base64');
  var dst = new Buffer(src.length + bytes.length);
  src.copy(dst, 0, 0, src.length);
  bytes.copy(dst, src.length, 0, bytes.length);

  return crypto.createHash('sha1').update(dst).digest('base64');
}