MediaWiki  REL1_31
CryptHKDF.php
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1 <?php
33 class CryptHKDF {
34 
38  protected $cache = null;
39 
43  protected $cacheKey = null;
44 
48  protected $algorithm = null;
49 
54  protected $salt = '';
55 
59  private $prk = '';
60 
67  private $skm;
68 
72  protected $lastK;
73 
80  protected $context = [];
81 
88  public static $hashLength = [
89  'md5' => 16,
90  'sha1' => 20,
91  'sha224' => 28,
92  'sha256' => 32,
93  'sha384' => 48,
94  'sha512' => 64,
95  'ripemd128' => 16,
96  'ripemd160' => 20,
97  'ripemd256' => 32,
98  'ripemd320' => 40,
99  'whirlpool' => 64,
100  ];
101 
105  private $cryptRand;
106 
115  public function __construct( $secretKeyMaterial, $algorithm, BagOStuff $cache, $context,
117  ) {
118  if ( strlen( $secretKeyMaterial ) < 16 ) {
119  throw new InvalidArgumentException( "secret was too short." );
120  }
121  $this->skm = $secretKeyMaterial;
122  $this->algorithm = $algorithm;
123  $this->cache = $cache;
124  $this->context = is_array( $context ) ? $context : [ $context ];
125  $this->cryptRand = $cryptRand;
126 
127  // To prevent every call from hitting the same memcache server, pick
128  // from a set of keys to use. mt_rand is only use to pick a random
129  // server, and does not affect the security of the process.
130  $this->cacheKey = $cache->makeKey( 'HKDF', mt_rand( 0, 16 ) );
131  }
132 
138  function __destruct() {
139  if ( $this->lastK ) {
140  $this->cache->set( $this->cacheKey, $this->lastK );
141  }
142  }
143 
148  protected function getSaltUsingCache() {
149  if ( $this->salt == '' ) {
150  $lastSalt = $this->cache->get( $this->cacheKey );
151  if ( $lastSalt === false ) {
152  // If we don't have a previous value to use as our salt, we use
153  // 16 bytes from CryptRand, which will use a small amount of
154  // entropy from our pool. Note, "XTR may be deterministic or keyed
155  // via an optional “salt value” (i.e., a non-secret random
156  // value)..." - http://eprint.iacr.org/2010/264.pdf. However, we
157  // use a strongly random value since we can.
158  $lastSalt = $this->cryptRand->generate( 16 );
159  }
160  // Get a binary string that is hashLen long
161  $this->salt = hash( $this->algorithm, $lastSalt, true );
162  }
163  return $this->salt;
164  }
165 
174  public function generate( $bytes, $context = '' ) {
175  if ( $this->prk === '' ) {
176  $salt = $this->getSaltUsingCache();
177  $this->prk = self::HKDFExtract(
178  $this->algorithm,
179  $salt,
180  $this->skm
181  );
182  }
183 
184  $CTXinfo = implode( ':', array_merge( $this->context, [ $context ] ) );
185 
186  return self::HKDFExpand(
187  $this->algorithm,
188  $this->prk,
189  $CTXinfo,
190  $bytes,
191  $this->lastK
192  );
193  }
194 
224  public static function HKDF( $hash, $ikm, $salt, $info, $L ) {
225  $prk = self::HKDFExtract( $hash, $salt, $ikm );
226  $okm = self::HKDFExpand( $hash, $prk, $info, $L );
227  return $okm;
228  }
229 
240  private static function HKDFExtract( $hash, $salt, $ikm ) {
241  return hash_hmac( $hash, $ikm, $salt, true );
242  }
243 
259  private static function HKDFExpand( $hash, $prk, $info, $bytes, &$lastK = '' ) {
260  $hashLen = self::$hashLength[$hash];
261  $rounds = ceil( $bytes / $hashLen );
262  $output = '';
263 
264  if ( $bytes > 255 * $hashLen ) {
265  throw new InvalidArgumentException( 'Too many bytes requested from HDKFExpand' );
266  }
267 
268  // K(1) = HMAC(PRK, CTXinfo || 1);
269  // K(i) = HMAC(PRK, K(i-1) || CTXinfo || i); 1 < i <= t;
270  for ( $counter = 1; $counter <= $rounds; ++$counter ) {
271  $lastK = hash_hmac(
272  $hash,
273  $lastK . $info . chr( $counter ),
274  $prk,
275  true
276  );
277  $output .= $lastK;
278  }
279 
280  return substr( $output, 0, $bytes );
281  }
282 }
CryptHKDF\getSaltUsingCache
getSaltUsingCache()
MW specific salt, cached from last run.
Definition: CryptHKDF.php:148
CryptHKDF\HKDFExpand
static HKDFExpand( $hash, $prk, $info, $bytes, &$lastK='')
Expand the key with the given context.
Definition: CryptHKDF.php:259
array
the array() calling protocol came about after MediaWiki 1.4rc1.
$output
static configuration should be added through ResourceLoaderGetConfigVars instead can be used to get the real title after the basic globals have been set but before ordinary actions take place $output
Definition: hooks.txt:2255
BagOStuff
interface is intended to be more or less compatible with the PHP memcached client.
Definition: BagOStuff.php:47
BagOStuff\makeKey
makeKey( $class, $component=null)
Make a cache key, scoped to this instance's keyspace.
Definition: BagOStuff.php:769
cache
you have access to all of the normal MediaWiki so you can get a DB use the cache
Definition: maintenance.txt:55
CryptHKDF\HKDFExtract
static HKDFExtract( $hash, $salt, $ikm)
Extract the PRK, PRK = HMAC(XTS, SKM) Note that the hmac is keyed with XTS (the salt),...
Definition: CryptHKDF.php:240
php
injection txt This is an overview of how MediaWiki makes use of dependency injection The design described here grew from the discussion of RFC T384 The term dependency this means that anything an object needs to operate should be injected from the the object itself should only know narrow no concrete implementation of the logic it relies on The requirement to inject everything typically results in an architecture that based on two main types of and essentially stateless service objects that use other service objects to operate on the value objects As of the beginning MediaWiki is only starting to use the DI approach Much of the code still relies on global state or direct resulting in a highly cyclical dependency which acts as the top level factory for services in MediaWiki which can be used to gain access to default instances of various services MediaWikiServices however also allows new services to be defined and default services to be redefined Services are defined or redefined by providing a callback the instantiator that will return a new instance of the service When it will create an instance of MediaWikiServices and populate it with the services defined in the files listed by thereby bootstrapping the DI framework Per $wgServiceWiringFiles lists includes ServiceWiring php
Definition: injection.txt:37
CryptHKDF\$salt
string $salt
binary string, the salt for the HKDF
Definition: CryptHKDF.php:54
CryptHKDF\generate
generate( $bytes, $context='')
Produce $bytes of secure random data.
Definition: CryptHKDF.php:174
CryptHKDF\__construct
__construct( $secretKeyMaterial, $algorithm, BagOStuff $cache, $context, CryptRand $cryptRand)
Definition: CryptHKDF.php:115
CryptHKDF\$cryptRand
CryptRand $cryptRand
Definition: CryptHKDF.php:105
CryptHKDF\HKDF
static HKDF( $hash, $ikm, $salt, $info, $L)
RFC5869 defines HKDF in 2 steps, extraction and expansion.
Definition: CryptHKDF.php:224
CryptHKDF
Definition: CryptHKDF.php:33
CryptHKDF\$hashLength
static int[] $hashLength
Round count is computed based on the hash'es output length, which neither php nor openssl seem to pro...
Definition: CryptHKDF.php:88
CryptHKDF\$cache
BagOStuff $cache
The persistent cache.
Definition: CryptHKDF.php:38
CryptHKDF\$algorithm
string $algorithm
The hash algorithm being used.
Definition: CryptHKDF.php:48
CryptHKDF\$prk
string $prk
The pseudorandom key.
Definition: CryptHKDF.php:59
CryptHKDF\__destruct
__destruct()
Save the last block generated, so the next user will compute a different PRK from the same SKM.
Definition: CryptHKDF.php:138
CryptHKDF\$context
array $context
a "context information" string CTXinfo (which may be null) See http://eprint.iacr....
Definition: CryptHKDF.php:80
CryptHKDF\$lastK
string $lastK
The last block (K(i)) of the most recent expanded key.
Definition: CryptHKDF.php:72
CryptRand
Definition: CryptRand.php:28
CryptHKDF\$skm
string $skm
The secret key material.
Definition: CryptHKDF.php:67
CryptHKDF\$cacheKey
string $cacheKey
Cache key we'll use for our salt.
Definition: CryptHKDF.php:43