Auth_OpenID_CryptUtil Class Reference

Collaboration diagram for Auth_OpenID_CryptUtil:

Static Public Member Functions
static	getBytes ($num_bytes)
	Get the specified number of random bytes. More...
static	randomString ($length, $population=null)
	Produce a string of length random bytes, chosen from chrs. More...

Detailed Description

Definition at line 26 of file CryptUtil.php.

Member Function Documentation

getBytes()

static Auth_OpenID_CryptUtil::getBytes (   $num_bytes )

static

Get the specified number of random bytes.

Attempts to use a cryptographically secure (not predictable) source of randomness if available. If there is no high-entropy randomness source available, it will fail. As a last resort, for non-critical systems, define Auth_OpenID_RAND_SOURCE as null, and the code will fall back on a pseudo-random number generator.

Parameters

int

$num_bytes

The length of the return value

Returns

string $bytes random bytes

Definition at line 40 of file CryptUtil.php.

    {
        static $f = null;
        $bytes = '';
        if ($f === null) {
            if (Auth_OpenID_RAND_SOURCE === null) {
                $f = false;
            } else {
                $f = @fopen(Auth_OpenID_RAND_SOURCE, "r");
                if ($f === false) {
                    $msg = 'Define Auth_OpenID_RAND_SOURCE as null to ' .
                        ' continue with an insecure random number generator.';
                    trigger_error($msg, E_USER_ERROR);
                }
            }
        }
        if ($f === false) {
            // pseudorandom used
            $bytes = '';
            for ($i = 0; $i < $num_bytes; $i += 4) {
                $bytes .= pack('L', mt_rand());
            }
            $bytes = substr($bytes, 0, $num_bytes);
        } else {
            $bytes = fread($f, $num_bytes);
        }
        return $bytes;
    }

Referenced by Auth_OpenID_Signatory\createAssociation(), Auth_OpenID_MathLibrary\rand(), and randomString().

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randomString()

static Auth_OpenID_CryptUtil::randomString (   $length,   $population = null  )

static

Produce a string of length random bytes, chosen from chrs.

If $chrs is null, the resulting string may contain any characters.

Parameters

integer	$length	The length of the resulting randomly-generated string
string	$chrs	A string of characters from which to choose to build the new string

Returns

string $result A string of randomly-chosen characters from $chrs

Definition at line 80 of file CryptUtil.php.

    {
        if ($population === null) {
            return Auth_OpenID_CryptUtil::getBytes($length);
        }
 
        $popsize = strlen($population);
 
        if ($popsize > 256) {
            $msg = 'More than 256 characters supplied to ' . __FUNCTION__;
            trigger_error($msg, E_USER_ERROR);
        }
 
        $duplicate = 256 % $popsize;
 
        $str = "";
        for ($i = 0; $i < $length; $i++) {
            do {
                $n = ord(Auth_OpenID_CryptUtil::getBytes(1));
            } while ($n < $duplicate);
 
            $n %= $popsize;
            $str .= $population[$n];
        }
 
        return $str;
    }

References $n, and getBytes().

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The documentation for this class was generated from the following file:

• Services/OpenId/lib/Auth/OpenID/CryptUtil.php