Introducing compatibility layers

 - Limited support for mbstring (mb_strlen(), mb_strpos(), mb_substr() only) via iconv.
   Falls back to regular strlen(), strpos(), substr() if iconv is not available.
 - Password hashing, dependant on CRYPT_BLOWFISH (2y version, available since PHP 5.3.7) availability.
diff --git a/tests/Bootstrap.php b/tests/Bootstrap.php
index 7f10ea1..439c7fd 100644
--- a/tests/Bootstrap.php
+++ b/tests/Bootstrap.php
@@ -63,6 +63,9 @@
 	defined('ICONV_ENABLED') OR define('ICONV_ENABLED', FALSE);
 }
 
+include_once SYSTEM_PATH.'core/compat/mbstring.php';
+include_once SYSTEM_PATH.'core/compat/password.php';
+
 include_once $dir.'/mocks/autoloader.php';
 spl_autoload_register('autoload');
 
diff --git a/tests/codeigniter/core/compat/mbstring_test.php b/tests/codeigniter/core/compat/mbstring_test.php
new file mode 100644
index 0000000..4152224
--- /dev/null
+++ b/tests/codeigniter/core/compat/mbstring_test.php
@@ -0,0 +1,54 @@
+<?php
+
+class mbstring_test extends CI_TestCase {
+
+	public function test_bootstrap()
+	{
+		if (MB_ENABLED)
+		{
+			return $this->markTestSkipped('ext/mbstring is loaded');
+		}
+
+		$this->assertTrue(function_exists('mb_strlen'));
+		$this->assertTrue(function_exists('mb_substr'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * @depends	test_bootstrap
+	 */
+	public function test_mb_strlen()
+	{
+		$this->assertEquals(ICONV_ENABLED ? 4 : 8, mb_strlen('тест'));
+		$this->assertEquals(ICONV_ENABLED ? 4 : 8, mb_strlen('тест', 'UTF-8'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * @depends	test_boostrap
+	 */
+	public function test_mb_strpos()
+	{
+		$this->assertEquals(ICONV_ENABLED ? 3 : 6, mb_strpos('тест', 'с'));
+		$this->assertFalse(mb_strpos('тест', 'с', 3));
+		$this->assertEquals(ICONV_ENABLED ? 3 : 6, mb_strpos('тест', 'с', 1, 'UTF-8'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * @depends	test_boostrap
+	 */
+	public function test_mb_substr()
+	{
+		$this->assertEquals(ICONV_ENABLED ? 'стинг' : 'естинг', mb_substr('тестинг', 2));
+		$this->assertEquals(ICONV_ENABLED ? 'нг' : 'г', mb_substr('тестинг', -2));
+		$this->assertEquals(ICONV_ENABLED ? 'ст' : 'е', mb_substr('тестинг', 2, 2));
+		$this->assertEquals(ICONV_ENABLED ? 'стинг' : 'естинг', mb_substr('тестинг', 2, 'UTF-8'));
+		$this->assertEquals(ICONV_ENABLED ? 'нг' : 'г', mb_substr('тестинг', -2, 'UTF-8'));
+		$this->assertEquals(ICONV_ENABLED ? 'ст' : 'е', mb_substr('тестинг', 2, 2, 'UTF-8'));
+	}
+
+}
\ No newline at end of file
diff --git a/tests/codeigniter/core/compat/password_test.php b/tests/codeigniter/core/compat/password_test.php
new file mode 100644
index 0000000..4014e74
--- /dev/null
+++ b/tests/codeigniter/core/compat/password_test.php
@@ -0,0 +1,158 @@
+<?php
+
+class password_test extends CI_TestCase {
+
+	public function test_bootstrap()
+	{
+		if (is_php('5.5'))
+		{
+			return $this->markTestSkipped('ext/standard/password is available on PHP 5.5');
+		}
+		elseif ( ! is_php('5.3.7'))
+		{
+			$this->assertFalse(defined('PASSWORD_BCRYPT'));
+			return $this->markTestSkipped("PHP versions prior to 5.3.7 don't have the '2y' Blowfish version");
+		}
+		elseif ( ! defined('CRYPT_BLOWFISH') OR CRYPT_BLOWFISH !== 1)
+		{
+			$this->assertFalse(defined('PASSWORD_BCRYPT'));
+			return $this->markTestSkipped('CRYPT_BLOWFISH is not available');
+		}
+
+		$this->assertTrue(defined('PASSWORD_BCRYPT'));
+		$this->assertTrue(defined('PASSWORD_DEFAULT'));
+		$this->assertEquals(1, PASSWORD_BCRYPT);
+		$this->assertEquals(PASSWORD_BCRYPT, PASSWORD_DEFAULT);
+		$this->assertTrue(function_exists('password_get_info'));
+		$this->assertTrue(function_exists('password_hash'));
+		$this->assertTrue(function_exists('password_needs_rehash'));
+		$this->assertTrue(function_exists('password_verify'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * password_get_info() test
+	 *
+	 * Borrowed from PHP's own tests
+	 *
+	 * @depends	test_bootstrap
+	 */
+	public function test_password_get_info()
+	{
+		$expected = array(
+			'algo' => 1,
+			'algoName' => 'bcrypt',
+			'options' => array('cost' => 10)
+		);
+
+		// default
+		$this->assertEquals($expected, password_get_info('$2y$10$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y'));
+
+		$expected['options']['cost'] = 11;
+
+		// cost
+		$this->assertEquals($expected, password_get_info('$2y$11$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y'));
+
+		$expected = array(
+			'algo' => 0,
+			'algoName' => 'unknown',
+			'options' => array()
+		);
+
+		// invalid length
+		$this->assertEquals($expected, password_get_info('$2y$11$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100'));
+
+		// non-bcrypt
+		$this->assertEquals($expected, password_get_info('$1$rasmusle$rISCgZzpwk3UhDidwXvin0'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * password_hash() test
+	 *
+	 * Borrowed from PHP's own tests
+	 *
+	 * @depends	test_bootstrap
+	 */
+	public function test_password_hash()
+	{
+		// FALSE is returned if no CSPRNG source is available
+		if ( ! defined('MCRYPT_DEV_URANDOM') && ! function_exists('openssl_random_pseudo_bytes')
+			&& (DIRECTORY_SEPARATOR !== '/' OR ! is_readable('/dev/arandom') OR ! is_readable('/dev/urandom'))
+			)
+		{
+			$this->assertFalse(password_hash('foo', PASSWORD_BCRYPT));
+		}
+		else
+		{
+			$this->assertEquals(60, strlen(password_hash('foo', PASSWORD_BCRYPT)));
+			$this->assertTrue(($hash = password_hash('foo', PASSWORD_BCRYPT)) === crypt('foo', $hash));
+		}
+
+		$this->assertEquals(
+			'$2y$07$usesomesillystringfore2uDLvp1Ii2e./U9C8sBjqp8I90dH6hi',
+			password_hash('rasmuslerdorf', PASSWORD_BCRYPT, array('cost' => 7, 'salt' => 'usesomesillystringforsalt'))
+		);
+
+		$this->assertEquals(
+			'$2y$10$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y',
+			password_hash('test', PASSWORD_BCRYPT, array('salt' => '123456789012345678901'.chr(0)))
+		);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * password_needs_rehash() test
+	 *
+	 * Borrowed from PHP's own tests
+	 *
+	 * @depends	test_password_get_info
+	 */
+	public function test_password_needs_rehash()
+	{
+		// invalid hash: always rehash
+		$this->assertTrue(password_needs_rehash('', PASSWORD_BCRYPT));
+
+		// valid, because it's an unknown algorithm
+		$this->assertFalse(password_needs_rehash('', 0));
+
+		// valid with same cost
+		$this->assertFalse(password_needs_rehash('$2y$10$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y', PASSWORD_BCRYPT, array('cost' => 10)));
+
+		// valid with same cost and additional parameters
+		$this->assertFalse(password_needs_rehash('$2y$10$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y', PASSWORD_BCRYPT, array('cost' => 10, 'foo' => 3)));
+
+		// invalid: different (lower) cost
+		$this->assertTrue(password_needs_rehash('$2y$10$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y', PASSWORD_BCRYPT, array('cost' => 09)));
+
+		// invalid: different (higher) cost
+		$this->assertTrue(password_needs_rehash('$2y$10$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y', PASSWORD_BCRYPT, array('cost' => 11)));
+
+		// valid with default cost
+		$this->assertFalse(password_needs_rehash('$2y$'.str_pad(10, 2, '0', STR_PAD_LEFT).'$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y', PASSWORD_BCRYPT));
+
+		// invalid: 'foo' is cast to 0
+		$this->assertTrue(password_needs_rehash('$2y$10$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y', PASSWORD_BCRYPT, array('cost' => 'foo')));
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * password_verify() test
+	 *
+	 * Borrowed from PHP's own tests
+	 *
+	 * @depends	test_bootstrap
+	 */
+	public function test_password_verify()
+	{
+		$this->assertFalse(password_verify(123, 123));
+		$this->assertFalse(password_verify('foo', '$2a$07$usesomesillystringforsalt$'));
+		$this->assertFalse(password_verify('rasmusler', '$2a$07$usesomesillystringfore2uDLvp1Ii2e./U9C8sBjqp8I90dH6hi'));
+		$this->assertTrue(password_verify('rasmuslerdorf', '$2a$07$usesomesillystringfore2uDLvp1Ii2e./U9C8sBjqp8I90dH6hi'));
+	}
+
+}
\ No newline at end of file