Encryption: It's For More Than Just Passwords

ENCRYPTIONIt's For More Than Just Password

JOHN CONGDON

JOHN CONGDON• PHP Since 2003

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JOHN CONGDON• PHP Since 2003• SDPHP Organizer




JOHN CONGDON• PHP Since 2003• SDPHP Organizer• Developer for

Networx Online





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Networx Online• PhoneBurner.com• MeetingBurner.com





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• I am not a cryptographer




TODAY'S TOPICS

Hashing &

Encryption

The Evolution Of Password Maintenance

CLEAR TEXT

$username = $_POST['username'];$password = $_POST['password'];$user = getUserByUsername($username);$authenticated = false;if ($user->password == $password) { $authenticated = true;}

*example only: not meant to be used

MAJOR VULNERABILITY

• Server compromise give complete username and password list

• SQL-Injection does too

HASHING

CRYPTOGRAPHIC HASHING

CRYPTOGRAPHIC HASHINGWikipedia Definition: A cryptographic hash function is a hash function; that is, an algorithm that takes an arbitrary block of data and returns a fixed-size bitstring, the (cryptographic) hash value, such that any (accidental or intentional) change to the data will (with very high probability) change the hash value. The data to be encoded are often called the "message,"

and the hash value is sometimes called the message digest or simply the digest.



HASH



HASHMessage



HASH DigestMessage



HASHDigestMessage



HASHDigestMessage

1abcb33beeb811dca15f0ac3e47b88d9 unicorn



HASHDigestMessage

1abcb33beeb811dca15f0ac3e47b88d9 unicorn

MD5 EXAMPLE

$username = $_POST['username'];$password = $_POST['password'];$user = getUserByUsername($username);$authenticated = false;if ($user->password == md5($password)) { $authenticated = true;}


MD5 EXAMPLE

$username = $_POST['username'];$password = $_POST['password'];$user = getUserByUsername($username);$authenticated = false;if ($user->password == md5($password)) { $authenticated = true;}


AVAILABLE ALGORITHMS<?php print_r(hash_algos());Array ( [0] => md2 [1] => md4 [2] => md5 [3] => sha1 [4] => sha224 [5] => sha256 [6] => sha384 [7] => sha512 [8] => ripemd128 [9] => ripemd160 [10] => ripemd256 [11] => ripemd320 [12] => whirlpool [13] => tiger128,3 [14] => tiger160,3 [15] => tiger192,3 [16] => tiger128,4 [17] => tiger160,4 [18] => tiger192,4

[19] => snefru [20] => snefru256 [21] => gost [22] => gost-crypto [23] => adler32 [24] => crc32 [25] => crc32b [26] => fnv132 [27] => fnv1a32 [28] => fnv164 [29] => fnv1a64 [30] => joaat [31] => haval128,3 [32] => haval160,3 [33] => haval192,3 [34] => haval224,3 [35] => haval256,3

[36] => haval128,4 [37] => haval160,4 [38] => haval192,4 [39] => haval224,4 [40] => haval256,4 [41] => haval128,5 [42] => haval160,5 [43] => haval192,5 [44] => haval224,5 [45] => haval256,5 )

VULNERABILITIES

• SQL-Injection gives you hashed passwords

ADDING SALT

ADDING SALTIn cryptography, a salt is random data that is used as an additional input to a one-way function that hashes a password or passphrase.[1] The primary function of salts is to defend against dictionary attacks versus a list of password hashes and

against pre-computed rainbow table attacks.



$hash = md5('RAND_SALT' . $password);



$hash = md5('RAND_SALT' . $password);

RAND_SALT must come from a cryptographically secure source.

Do not use (rand, mt_rand, uniqid)Do use (/dev/urandom, mcrypt, openssl)

$username = $_POST['username'];$password = $_POST['password'];$user = getUserByUsername($username);$authenticated = false;if ($user->password == md5($user->salt . $password)) { $authenticated = true;}


MD5+SALT EXAMPLE

function generateUserPassword ($salt_string, $password) { $str1 = substr($salt_string, 0, 8); $str2 = substr($salt_string, 8); return md5($str1 . $password . $str2);}

function hashPassword($password){ return sha1( $this->Salt1 . $password . $this->Salt2 );}

USE TODAY'S STANDARDSCurrently: BCrypt

• Slower by design

• Configurable to help withstand the test of time

• Should be configured to take 0.25 to 0.50 seconds

• Start with a cost of 10, use higher if possible

https://github.com/johncongdon/bcrypt-cost-finder

PHP 5.5 Password Hashing APIhttp://www.php.net/manual/en/ref.password.php

PHP 5.5 Password Hashing API



$authenticated = false;if ($user->password == md5($password)) { $authenticated = true;}


function authenticate($user, $password) { $authenticated = false;

if ($user->password == md5($password)) { $authenticated = true; } return $authenticated }


function authenticate($user, $password) { $authenticated = false; $hash = $user->password; if (password_verify($password, $hash)) { $authenticated = true; } if ($user->password == md5($password)) { $authenticated = true; } return $authenticated }


$username = $_POST['username'];$password = $_POST['password'];$user = getUserByUsername($username);if (authenticate($user, $password)) { if (password_needs_rehash ($user->password, PASSWORD_DEFAULT)) { $user->password = password_hash($password, PASSWORD_DEFAULT); $user->save(); }}

I Lied: Available in PHP >= 5.3.7https://github.com/ircmaxell/password_compat

A forward compatible password API implementation that will work until you are ready to upgrade to 5.5. This will work for all versions of PHP that has the $2y fix.

Upgrading to 5.5 will not break your current code if you use this library.

https://github.com/ircmaxell/password_compat

Want More? Get Statistics Herehttp://blog.ircmaxell.com/2013/01/password-storage-talk-at-php-benelux-13.html

http://blog.ircmaxell.com/2013/01/password-storage-talk-at-php-benelux-13.html

Passwords Are Easy

We don't need to know it, except for user login

ENCRYPTION

AVOID ENCRYPTION AT ALL COSTS!


Clarification: Avoid storing any data that you need to encrypt.



Before deciding to collect and store this information, ask yourself why you need it.




Is the risk of potentially leaking this information worth the reward?





Are there any alternative solutions available to you?





Are there any alternative solutions available to you?Example: Credit card companies usually offer a token solution

SYMMETRIC VS ASYMMETRIC

SYMMETRIC VS ASYMMETRICSymmetric

Only one shared key Same key encrypts and decrypts Easiest to understand

SYMMETRIC VS ASYMMETRICSymmetric

Only one shared key Same key encrypts and decrypts Easiest to understand

Asymmetric

Two keys (Public and Private) Encryption/Decryption Public key encrypts Private key decrypts Signing/Verifying Private key signs Public key verifies

SYMMETRIC ENCRYPTIONa.k.a. Shared-Key Encryption

KEYS, CIPHERS, MODES, AND IV OH MY!


Keys should be easy enough (Keep it secret)



Ciphers



Ciphers Deterministic algorithm (Ex: 3DES, Blowfish, TwoFish)




Modes




Modes Determines how the key stream is used (never cross them)




Modes Determines how the key stream is used (never cross them) Avoid ECB (Electronic Code Book)




Modes Determines how the key stream is used (never cross them) Avoid ECB (Electronic Code Book) Use CBC or CFB, Cipher Block Chaining / Cipher FeedBack)





Initialization Vectors





Initialization Vectors Similar to SALT in hashing (It's not a secret)





Initialization Vectors Similar to SALT in hashing (It's not a secret) Must be random per encrypted text

EXAMPLE: ENCRYPT USING CRYPT

$crypt_key = 'MySecretKey';$message = "Do not tell my boss, but I did xyz";$iv_size = mcrypt_get_iv_size( MCRYPT_BLOWFISH, MCRYPT_MODE_CBC );$iv = mcrypt_create_iv($iv_size, MCRYPT_DEV_URANDOM);

$cipher = mcrypt_encrypt( MCRYPT_BLOWFISH, $crypt_key, $message, MCRYPT_MODE_CBC, $iv);

HMAC: HASH-BASED MESSAGE AUTHENTICATION CODE


Using a separate key, this will give us a signature of the encryption. We can use this to ensure that the data has not been tampered with.



When encrypting:



When encrypting:

Always encrypt first, and then get the signature of the Cipher Text.



When encrypting:


Store the signature with your IV and Cipher Text.



When encrypting:



When Decrypting:



When encrypting:



When Decrypting:

Always verify the signature first, and then decrypt if successful.

EXAMPLE: USING HMAC

$crypt_key = 'MySecretKey';$hmac_key = 'HashingKey';$hmac = hash_hmac('sha512', $cipher, $hmac_key);//Store it with your encrypted data $encoded_data = base64_encode($iv . $cipher . $hmac);

$decoded_data = base64_decode($encoded_data);$iv = substr($decoded_data, 0, $iv_size);$hmac = substr($decoded_data, -128);$cipher = substr($decoded_data, $iv_size, -128);if ($hmac != hash_hmac('sha512', $cipher, $hmac_key)){ throw new Exception('HMAC does not match');}$message = mcrypt_decrypt( MCRYPT_BLOWFISH, $crypt_key, $cipher, MCRYPT_MODE_CBC, $iv);

EXAMPLE: DECRYPTING USING HMAC

USE A LIBRARY

http://phpseclib.sourceforge.net

They've done the hard parts, save yourself the headache and just use it.

It's even PHP4+ compatible, so no excuses.

http://phpseclib.sourceforge.net

EXAMPLE: USING PHPSECLIB

$crypt_key = 'MySecretKey';$hmac_key = 'HashingKey';$message = "Do not tell my boss, but I did xyz";require 'Crypt/DES.php';require 'Crypt/Hash.php';$des = new Crypt_DES();$des->setKey($crypt_key);$cipher = $des->encrypt($message);$hash = new Crypt_Hash('sha512');$hash->setKey($hmac_key);$hmac = bin2hex($hash->hash($cipher));

EXAMPLE: USING PHPSECLIB

require 'Crypt/DES.php';require 'Crypt/Hash.php';$hash = new Crypt_Hash('sha512');$hash->setKey($hmac_key);$verify_hmac = bin2hex($hash->hash($cipher));if ($verify_hmac == $hmac) { $des = new Crypt_DES(); $des->setKey($crypt_key); $message = $des->decrypt($cipher);}

ASYMMETRIC ENCRYPTIONa.k.a. Public-Key Encryption

COMMON ASYMMETRIC USES

SSH Keys HTTPS / SSL PGP: Pretty Good Privacy Email Files Really any message

EXAMPLE: ASYMMETRIC CODE

http://codereaper.com/blog/2014/asymmetric-encryption-in-php/




openssl req -x509 -newkey rsa:2048 -keyout private.pem -out public.pem -days 365




$key = file_get_contents('public.pem');$public_key = openssl_get_publickey($key);$message = "Do not tell my boss, but I did xyz";$cipher = $e = null;openssl_seal($message, $cipher, $e, array($public_key));$sealed_data = base64_encode($cipher);$envelope = base64_encode($e[0]);

openssl req -x509 -newkey rsa:2048 -keyout private.pem -out public.pem -days 365




$key = file_get_contents('private.pem');$priv_key = openssl_get_privatekey($key, $passphrase);

$input = base64_decode($sealed_data);$einput = base64_decode($envelope);$message = null;openssl_open($input, $message, $einput, $priv_key);


ENCRYPTION !== PROTECTION


Data obtained through SQL Injection attacks should be relatively secure.



For us to encrypt/decrypt, we must have access to the key. Therefore, any breach of the system will disclose the key to the attacker, leaving ALL encryption useless.



For us to encrypt/decrypt, we must have access to the key. Therefore, any breach of the system will disclose the key to the attacker, leaving ALL encryption useless.

Apache environment variable, memory, config files, password entered during system start, etc... do not keep the key private.


There is no such thing as 100% secure.

OTHER THINGS TO CONSIDER


• Encrypt / decrypt on a separate server


• Encrypt / decrypt on a separate server• More overhead and complexity


• Encrypt / decrypt on a separate server• More overhead and complexity• Any server breach can still decrypt

data



data• With enough thought and monitoring,

you can kill the decryption server to limit the damage done





• Think about restricting requests per second





• Think about restricting requests per second

Paranoid about password safety? Consider encrypting the hash. Renders SQL Injection and rainbow tables/brute force mostly useless without the key.



Do you need access to the user's information without them on the system?


Do you need access to the user's information without them on the system?

If your user must be present, then consider making them partially responsible for the security. Have them use a second password or passphrase that you can add to your key to use in the encryption.

FINAL WORDS...

I've learned a ton while preparing this presentation.

Thanks especially to Anthony Ferrara (@ircmaxell)

http://blog.ircmaxell.com

http://blog.ircmaxell.com

THANK YOU!

Internet

Encryption: It's For More Than Just Passwords