Use ASP.NET membership in PHP

Question

I need to authenticate against an ASP.NET membership table in php. The membership api is configured to use a hashed password.

Can someone kindly give me the php to hash the password that came from a login form and compare it to the sql field?

I know the password that I'm passing in is correct, but it's not hashing the same.

private function Auth( $username, $password )
{
    // Hashed password in db
    $hash = $this->parent->_memberData['conv_password'];

    // password passed from form
    $bytes = mb_convert_encoding($password, 'UTF-7');       

    // Salt from db
    $salt = base64_decode($this->parent->_memberData['misc']);

    // hash password from form with salt
    $hashedpassword = base64_encode(sha1($salt . $bytes, true));

    // Test em out
    if ($hashedpassword == $hash)
    {
        $this->return_code = "SUCCESS";
        return true;
    }
    else
    {
        $this->return_code = "WRONG_AUTH";
        return false;
    }
}

UPDATE:

I've tried different encodings with same results. UTF-7, UTF-8, and UTF-16.

UPDATE: I've been battling this for a week now. Bounty coming right up...

Here's the .net code in the form of a unit test. The unit test works and the values are straight out of the database. What's the correct translation of this code to php?

public void EncodePassword()
        {
        string expected = "aP/mqBu3VkX+rIna42ramuosS3s=";
        string salt = "urIaGX0zd/oBRMDZjc1CKw==";
        string pass = "Comeonman";

        byte[] bytes = Encoding.Unicode.GetBytes(pass);
        byte[] numArray = Convert.FromBase64String(salt);
        byte[] numArray1 = new byte[(int)numArray.Length + (int)bytes.Length];
        byte[] numArray2 = null;
        Buffer.BlockCopy(numArray, 0, numArray1, 0, (int)numArray.Length);
        Buffer.BlockCopy(bytes, 0, numArray1, (int)numArray.Length, (int)bytes.Length);

            HashAlgorithm hashAlgorithm = HashAlgorithm.Create("SHA1");
            if (hashAlgorithm != null)
            {
                numArray2 = hashAlgorithm.ComputeHash(numArray1);
            }

        Assert.AreEqual(Convert.ToBase64String(numArray2), expected);
    }

Answer 1

$password = 'Comeonman';
$salt = base64_decode('urIaGX0zd/oBRMDZjc1CKw=='); 
$utf16Password = mb_convert_encoding($password, 'UTF-16LE', 'UTF-8');
echo base64_encode(sha1($salt.$utf16Password, true));