Long story short have a membership system built in .NET that we are porting to WordPress and need to replicate the PBKDF2 encryption so users don't need to reset their passwords.
Using a know hashed password I've been able to replicate this in .NET easily, with the following code:
static void Main(string[] args)
{
var isValid = CheckPassword("#0zEZcD7uNmv", "5SyOX+Rbclzvvit3MEM2nBRaPVo2M7ZTs7n3znXTfyW4OhwTlJLvpcUlCryblgkQ");
}
public static int PBKDF2IterCount = 10000;
public static int PBKDF2SubkeyLength = 256 / 8; // 256 bits
public static int SaltSize = 128 / 8; // 128 bits
private static bool CheckPassword(string Password, string ExistingHashedPassword)
{
byte[] saltAndPassword = Convert.FromBase64String(ExistingHashedPassword);
byte[] salt = new byte[SaltSize];
Array.Copy(saltAndPassword, 0, salt, 0, SaltSize);
Console.WriteLine("--Salt--");
Console.WriteLine(Convert.ToBase64String(salt));
string hashedPassword = HashPassword(Password, salt);
Console.WriteLine("--HashedPassword--");
Console.WriteLine(hashedPassword);
return hashedPassword == ExistingHashedPassword;
}
private static string HashPassword(string Password, byte[] salt)
{
byte[] hash = new byte[PBKDF2SubkeyLength];
using (var pbkdf2 = new Rfc2898DeriveBytes(Password, salt, PBKDF2IterCount))
{
hash = pbkdf2.GetBytes(PBKDF2SubkeyLength);
}
byte[] hashBytes = new byte[PBKDF2SubkeyLength + SaltSize];
Array.Copy(salt, 0, hashBytes, 0, SaltSize);
Array.Copy(hash, 0, hashBytes, SaltSize, PBKDF2SubkeyLength);
string hashedPassword = Convert.ToBase64String(hashBytes);
return hashedPassword;
}
The console app will produce the following:
--Salt--
5SyOX+Rbclzvvit3MEM2nA==
--HashedPassword--
5SyOX+Rbclzvvit3MEM2nBRaPVo2M7ZTs7n3znXTfyW4OhwTlJLvpcUlCryblgkQ
--IsValid--
True
However in the PHP side I can't get the same results. My code so far is below.
$mySalt = base64_decode('5SyOX+Rbclzvvit3MEM2nA==');
$dev = pbkdf2('sha1', '#0zEZcD7uNmv', $mySalt, 10000, 48, true);
$key = substr($dev, 0, 32); //Keylength: 32
$iv = substr($dev, 32, 16); // IV-length: 16
echo 'PHP<br/>';
echo 'PASS: '.base64_encode($dev).'<br/>';
echo 'SALT: '.base64_encode($iv).'<br/><br/>';
echo '.NET<br/>';
echo 'PASS: 5SyOX+Rbclzvvit3MEM2nBRaPVo2M7ZTs7n3znXTfyW4OhwTlJLvpcUlCryblgkQ<br/>';
echo 'SALT: 5SyOX+Rbclzvvit3MEM2nA==<br/><br/>';
function pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output = false)
{
$algorithm = strtolower($algorithm);
if(!in_array($algorithm, hash_algos(), true))
die('PBKDF2 ERROR: Invalid hash algorithm.');
if($count <= 0 || $key_length <= 0)
die('PBKDF2 ERROR: Invalid parameters.');
$hash_length = strlen(hash($algorithm, "", true));
$block_count = ceil($key_length / $hash_length);
$output = "";
for($i = 1; $i <= $block_count; $i++) {
// $i encoded as 4 bytes, big endian.
$last = $salt . pack("N", $i);
// first iteration
$last = $xorsum = hash_hmac($algorithm, $last, $password, true);
// perform the other $count - 1 iterations
for ($j = 1; $j < $count; $j++) {
$xorsum ^= ($last = hash_hmac($algorithm, $last, $password, true));
}
$output .= $xorsum;
}
return substr($output, 0, $key_length);
}
And the results are:
PHP
PASS: FFo9WjYztlOzuffOddN/Jbg6HBOUku+lxSUKvJuWCRCsYe+1Tgbb8Ob4FtxumMal
SALT: rGHvtU4G2/Dm+BbcbpjGpQ==
.NET
PASS: 5SyOX+Rbclzvvit3MEM2nBRaPVo2M7ZTs7n3znXTfyW4OhwTlJLvpcUlCryblgkQ
SALT: 5SyOX+Rbclzvvit3MEM2nA==
Any help would be appreciated.
$ivand labelling it SALT. Next I'll question of strlen is appropriate. But the harder to see one is that .NET turns the string password into bytes via UTF-8. If PHP uses UCS-2 or UTF-16 then your binary HMAC keys aren't the same. – Nikolos