Created
November 7, 2011 16:59
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phpSec key history
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<?php | |
/* Check key size. */ | |
$keySize = strlen($key); | |
$keySizes = mcrypt_enc_get_supported_key_sizes($td); | |
if(count($keySizes) > 0) { | |
/* Encryption method requires a specific key size. */ | |
if(!in_array($keySize, $keySizes)) { | |
phpsec::error('Key is out of range. Should be one of: '. var_export($keySizes ,1)); | |
return false; | |
} | |
} else { | |
/* No spsecific size is needed. */ | |
if($keySize == 0 || $keySize > mcrypt_enc_get_key_size($td)) { | |
phpsec::error('Key is out of range. Should be: 1 - ' . mcrypt_enc_get_key_size($td).' bytes.'); | |
return false; | |
} | |
} |
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<?php | |
/** | |
* Get a key from a secret. | |
* What we do is create two different hashes from the secret, combine them | |
* and pick out the number of characters we need. | |
* We used the raw binary output of the hash function for maximum | |
* bit strength (we have 255 chars to choose from, instead of 16). | |
* | |
* @param string $secret | |
* The secret to generate a key from. | |
* | |
* @param integer $ks | |
* The key size. | |
* | |
* @return binary | |
* Key created from secret. | |
*/ | |
private static function getKey($secret, $ks) { | |
/* Split the secret into two parts. */ | |
$secretSplit = floor(strlen($secret)); | |
$secret1 = substr($secret, 0, $secretSplit); | |
$secret2 = substr($secret, $secretSplit); | |
/* Hash the two parts seperatly and return the result in raw format. */ | |
$key1 = hash('sha256', $secret1, true); | |
$key2 = hash('sha256', $secret2, true); | |
/* Return the part of the key we need. */ | |
return substr($key2.$key1, 0, $ks); | |
} |
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