bug #470, use a dedicated lib to generate random bytes

11 files changed, 1170 insertions, 26 deletions

diff --git a/include/functions_session.inc.php b/include/functions_session.inc.php
index fe43bc570..0829bcfda 100644
--- a/include/functions_session.inc.php
+++ b/include/functions_session.inc.php
@@ -62,32 +62,17 @@ if (isset($conf['session_save_handler'])
  */
 function generate_key($size)
 {
-  if (
-    is_callable('openssl_random_pseudo_bytes')
-    and !(version_compare(PHP_VERSION, '5.3.4') < 0 and defined('PHP_WINDOWS_VERSION_MAJOR'))
-    )
-  {
-    return substr(
-      str_replace(
-        array('+', '/'),
-        '',
-        base64_encode(openssl_random_pseudo_bytes($size+10))
-        ),
-      0,
-      $size
-      );
-  }
-  else
-  {
-    $alphabet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
-    $l = strlen($alphabet)-1;
-    $key = '';
-    for ($i=0; $i<$size; $i++)
-    {
-      $key.= $alphabet[mt_rand(0, $l)];
-    }
-    return $key;
-  }
+  include_once(PHPWG_ROOT_PATH.'include/random_compat/random.php');
+
+  return substr(
+    str_replace(
+      array('+', '/'),
+      '',
+      base64_encode(random_bytes($size+10))
+      ),
+    0,
+    $size
+    );
 }
 
 /**
diff --git a/include/random_compat/byte_safe_strings.php b/include/random_compat/byte_safe_strings.php
new file mode 100644
index 000000000..dec5d3062
--- /dev/null
+++ b/include/random_compat/byte_safe_strings.php
@@ -0,0 +1,181 @@
+<?php
+/**
+ * Random_* Compatibility Library
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+if (!function_exists('RandomCompat_strlen')) {
+    if (
+        defined('MB_OVERLOAD_STRING') &&
+        ini_get('mbstring.func_overload') & MB_OVERLOAD_STRING
+    ) {
+        /**
+         * strlen() implementation that isn't brittle to mbstring.func_overload
+         *
+         * This version uses mb_strlen() in '8bit' mode to treat strings as raw
+         * binary rather than UTF-8, ISO-8859-1, etc
+         *
+         * @param string $binary_string
+         *
+         * @throws TypeError
+         *
+         * @return int
+         */
+        function RandomCompat_strlen($binary_string)
+        {
+            if (!is_string($binary_string)) {
+                throw new TypeError(
+                    'RandomCompat_strlen() expects a string'
+                );
+            }
+
+            return mb_strlen($binary_string, '8bit');
+        }
+
+    } else {
+        /**
+         * strlen() implementation that isn't brittle to mbstring.func_overload
+         *
+         * This version just used the default strlen()
+         *
+         * @param string $binary_string
+         *
+         * @throws TypeError
+         *
+         * @return int
+         */
+        function RandomCompat_strlen($binary_string)
+        {
+            if (!is_string($binary_string)) {
+                throw new TypeError(
+                    'RandomCompat_strlen() expects a string'
+                );
+            }
+            return strlen($binary_string);
+        }
+    }
+}
+
+if (!function_exists('RandomCompat_substr')) {
+
+    if (
+        defined('MB_OVERLOAD_STRING')
+        &&
+        ini_get('mbstring.func_overload') & MB_OVERLOAD_STRING
+    ) {
+        /**
+         * substr() implementation that isn't brittle to mbstring.func_overload
+         *
+         * This version uses mb_substr() in '8bit' mode to treat strings as raw
+         * binary rather than UTF-8, ISO-8859-1, etc
+         *
+         * @param string $binary_string
+         * @param int $start
+         * @param int $length (optional)
+         *
+         * @throws TypeError
+         *
+         * @return string
+         */
+        function RandomCompat_substr($binary_string, $start, $length = null)
+        {
+            if (!is_string($binary_string)) {
+                throw new TypeError(
+                    'RandomCompat_substr(): First argument should be a string'
+                );
+            }
+
+            if (!is_int($start)) {
+                throw new TypeError(
+                    'RandomCompat_substr(): Second argument should be an integer'
+                );
+            }
+
+            if ($length === null) {
+                /**
+                 * mb_substr($str, 0, NULL, '8bit') returns an empty string on
+                 * PHP 5.3, so we have to find the length ourselves.
+                 */
+                $length = RandomCompat_strlen($length) - $start;
+            } elseif (!is_int($length)) {
+                throw new TypeError(
+                    'RandomCompat_substr(): Third argument should be an integer, or omitted'
+                );
+            }
+
+            // Consistency with PHP's behavior
+            if ($start === RandomCompat_strlen($binary_string) && $length === 0) {
+                return '';
+            }
+            if ($start > RandomCompat_strlen($binary_string)) {
+                return false;
+            }
+
+            return mb_substr($binary_string, $start, $length, '8bit');
+        }
+
+    } else {
+
+        /**
+         * substr() implementation that isn't brittle to mbstring.func_overload
+         *
+         * This version just uses the default substr()
+         *
+         * @param string $binary_string
+         * @param int $start
+         * @param int $length (optional)
+         *
+         * @throws TypeError
+         *
+         * @return string
+         */
+        function RandomCompat_substr($binary_string, $start, $length = null)
+        {
+            if (!is_string($binary_string)) {
+                throw new TypeError(
+                    'RandomCompat_substr(): First argument should be a string'
+                );
+            }
+
+            if (!is_int($start)) {
+                throw new TypeError(
+                    'RandomCompat_substr(): Second argument should be an integer'
+                );
+            }
+
+            if ($length !== null) {
+                if (!is_int($length)) {
+                    throw new TypeError(
+                        'RandomCompat_substr(): Third argument should be an integer, or omitted'
+                    );
+                }
+
+                return substr($binary_string, $start, $length);
+            }
+
+            return substr($binary_string, $start);
+        }
+    }
+}
diff --git a/include/random_compat/cast_to_int.php b/include/random_compat/cast_to_int.php
new file mode 100644
index 000000000..f441c5d98
--- /dev/null
+++ b/include/random_compat/cast_to_int.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * Random_* Compatibility Library
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+if (!function_exists('RandomCompat_intval')) {
+    
+    /**
+     * Cast to an integer if we can, safely.
+     * 
+     * If you pass it a float in the range (~PHP_INT_MAX, PHP_INT_MAX)
+     * (non-inclusive), it will sanely cast it to an int. If you it's equal to
+     * ~PHP_INT_MAX or PHP_INT_MAX, we let it fail as not an integer. Floats 
+     * lose precision, so the <= and => operators might accidentally let a float
+     * through.
+     * 
+     * @param int|float $number    The number we want to convert to an int
+     * @param boolean   $fail_open Set to true to not throw an exception
+     * 
+     * @return int (or float if $fail_open)
+     *
+     * @throws TypeError
+     */
+    function RandomCompat_intval($number, $fail_open = false)
+    {
+        if (is_numeric($number)) {
+            $number += 0;
+        }
+
+        if (
+            is_float($number)
+            &&
+            $number > ~PHP_INT_MAX
+            &&
+            $number < PHP_INT_MAX
+        ) {
+            $number = (int) $number;
+        }
+
+        if (is_int($number) || $fail_open) {
+            return $number;
+        }
+
+        throw new TypeError(
+            'Expected an integer.'
+        );
+    }
+}
diff --git a/include/random_compat/error_polyfill.php b/include/random_compat/error_polyfill.php
new file mode 100644
index 000000000..57cfefdcd
--- /dev/null
+++ b/include/random_compat/error_polyfill.php
@@ -0,0 +1,42 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+if (!class_exists('Error', false)) {
+    // We can't really avoid making this extend Exception in PHP 5.
+    class Error extends Exception
+    {
+        
+    }
+}
+
+if (!class_exists('TypeError', false)) {
+    class TypeError extends Error
+    {
+        
+    }
+}
diff --git a/include/random_compat/random.php b/include/random_compat/random.php
new file mode 100644
index 000000000..a8802597d
--- /dev/null
+++ b/include/random_compat/random.php
@@ -0,0 +1,197 @@
+<?php
+/**
+ * Random_* Compatibility Library
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ *
+ * @version 2.0.2
+ * @released 2016-04-03
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+if (!defined('PHP_VERSION_ID')) {
+    // This constant was introduced in PHP 5.2.7
+    $RandomCompatversion = explode('.', PHP_VERSION);
+    define(
+        'PHP_VERSION_ID',
+        $RandomCompatversion[0] * 10000
+        + $RandomCompatversion[1] * 100
+        + $RandomCompatversion[2]
+    );
+    $RandomCompatversion = null;
+}
+
+if (PHP_VERSION_ID < 70000) {
+
+    if (!defined('RANDOM_COMPAT_READ_BUFFER')) {
+        define('RANDOM_COMPAT_READ_BUFFER', 8);
+    }
+
+    $RandomCompatDIR = dirname(__FILE__);
+
+    require_once $RandomCompatDIR.'/byte_safe_strings.php';
+    require_once $RandomCompatDIR.'/cast_to_int.php';
+    require_once $RandomCompatDIR.'/error_polyfill.php';
+
+    if (!function_exists('random_bytes')) {
+        /**
+         * PHP 5.2.0 - 5.6.x way to implement random_bytes()
+         *
+         * We use conditional statements here to define the function in accordance
+         * to the operating environment. It's a micro-optimization.
+         *
+         * In order of preference:
+         *   1. Use libsodium if available.
+         *   2. fread() /dev/urandom if available (never on Windows)
+         *   3. mcrypt_create_iv($bytes, MCRYPT_DEV_URANDOM)
+         *   4. COM('CAPICOM.Utilities.1')->GetRandom()
+         *   5. openssl_random_pseudo_bytes() (absolute last resort)
+         *
+         * See ERRATA.md for our reasoning behind this particular order
+         */
+        if (extension_loaded('libsodium')) {
+            // See random_bytes_libsodium.php
+            if (PHP_VERSION_ID >= 50300 && function_exists('\\Sodium\\randombytes_buf')) {
+                require_once $RandomCompatDIR.'/random_bytes_libsodium.php';
+            } elseif (method_exists('Sodium', 'randombytes_buf')) {
+                require_once $RandomCompatDIR.'/random_bytes_libsodium_legacy.php';
+            }
+        }
+
+        /**
+         * Reading directly from /dev/urandom:
+         */
+        if (DIRECTORY_SEPARATOR === '/') {
+            // DIRECTORY_SEPARATOR === '/' on Unix-like OSes -- this is a fast
+            // way to exclude Windows.
+            $RandomCompatUrandom = true;
+            $RandomCompat_basedir = ini_get('open_basedir');
+
+            if (!empty($RandomCompat_basedir)) {
+                $RandomCompat_open_basedir = explode(
+                    PATH_SEPARATOR,
+                    strtolower($RandomCompat_basedir)
+                );
+                $RandomCompatUrandom = (array() !== array_intersect(
+                    array('/dev', '/dev/', '/dev/urandom'),
+                    $RandomCompat_open_basedir
+                ));
+                $RandomCompat_open_basedir = null;
+            }
+
+            if (
+                !function_exists('random_bytes')
+                &&
+                $RandomCompatUrandom
+                &&
+                @is_readable('/dev/urandom')
+            ) {
+                // Error suppression on is_readable() in case of an open_basedir
+                // or safe_mode failure. All we care about is whether or not we
+                // can read it at this point. If the PHP environment is going to
+                // panic over trying to see if the file can be read in the first
+                // place, that is not helpful to us here.
+
+                // See random_bytes_dev_urandom.php
+                require_once $RandomCompatDIR.'/random_bytes_dev_urandom.php';
+            }
+            // Unset variables after use
+            $RandomCompat_basedir = null;
+        } else {
+            $RandomCompatUrandom = false;
+        }
+
+        /**
+         * mcrypt_create_iv()
+         */
+        if (
+            !function_exists('random_bytes')
+            &&
+            PHP_VERSION_ID >= 50307
+            &&
+            extension_loaded('mcrypt')
+            &&
+            (DIRECTORY_SEPARATOR !== '/' || $RandomCompatUrandom)
+        ) {
+            // Prevent this code from hanging indefinitely on non-Windows;
+            // see https://bugs.php.net/bug.php?id=69833
+            if (
+                DIRECTORY_SEPARATOR !== '/' || 
+                (PHP_VERSION_ID <= 50609 || PHP_VERSION_ID >= 50613)
+            ) {
+                // See random_bytes_mcrypt.php
+                require_once $RandomCompatDIR.'/random_bytes_mcrypt.php';
+            }
+        }
+        $RandomCompatUrandom = null;
+
+        if (
+            !function_exists('random_bytes')
+            &&
+            extension_loaded('com_dotnet')
+            &&
+            class_exists('COM')
+        ) {
+            $RandomCompat_disabled_classes = preg_split(
+                '#\s*,\s*#',
+                strtolower(ini_get('disable_classes'))
+            );
+
+            if (!in_array('com', $RandomCompat_disabled_classes)) {
+                try {
+                    $RandomCompatCOMtest = new COM('CAPICOM.Utilities.1');
+                    if (method_exists($RandomCompatCOMtest, 'GetRandom')) {
+                        // See random_bytes_com_dotnet.php
+                        require_once $RandomCompatDIR.'/random_bytes_com_dotnet.php';
+                    }
+                } catch (com_exception $e) {
+                    // Don't try to use it.
+                }
+            }
+            $RandomCompat_disabled_classes = null;
+            $RandomCompatCOMtest = null;
+        }
+
+        /**
+         * throw new Exception
+         */
+        if (!function_exists('random_bytes')) {
+            /**
+             * We don't have any more options, so let's throw an exception right now
+             * and hope the developer won't let it fail silently.
+             */
+            function random_bytes($length)
+            {
+                throw new Exception(
+                    'There is no suitable CSPRNG installed on your system'
+                );
+            }
+        }
+    }
+
+    if (!function_exists('random_int')) {
+        require_once $RandomCompatDIR.'/random_int.php';
+    }
+
+    $RandomCompatDIR = null;
+}
diff --git a/include/random_compat/random_bytes_com_dotnet.php b/include/random_compat/random_bytes_com_dotnet.php
new file mode 100644
index 000000000..342282549
--- /dev/null
+++ b/include/random_compat/random_bytes_com_dotnet.php
@@ -0,0 +1,81 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/**
+ * Windows with PHP < 5.3.0 will not have the function
+ * openssl_random_pseudo_bytes() available, so let's use
+ * CAPICOM to work around this deficiency.
+ * 
+ * @param int $bytes
+ * 
+ * @throws Exception
+ * 
+ * @return string
+ */
+function random_bytes($bytes)
+{
+    try {
+        $bytes = RandomCompat_intval($bytes);
+    } catch (TypeError $ex) {
+        throw new TypeError(
+            'random_bytes(): $bytes must be an integer'
+        );
+    }
+
+    if ($bytes < 1) {
+        throw new Error(
+            'Length must be greater than 0'
+        );
+    }
+
+    $buf = '';
+    $util = new COM('CAPICOM.Utilities.1');
+    $execCount = 0;
+
+    /**
+     * Let's not let it loop forever. If we run N times and fail to
+     * get N bytes of random data, then CAPICOM has failed us.
+     */
+    do {
+        $buf .= base64_decode($util->GetRandom($bytes, 0));
+        if (RandomCompat_strlen($buf) >= $bytes) {
+            /**
+             * Return our random entropy buffer here:
+             */
+            return RandomCompat_substr($buf, 0, $bytes);
+        }
+        ++$execCount; 
+    } while ($execCount < $bytes);
+
+    /**
+     * If we reach here, PHP has failed us.
+     */
+    throw new Exception(
+        'Could not gather sufficient random data'
+    );
+}
diff --git a/include/random_compat/random_bytes_dev_urandom.php b/include/random_compat/random_bytes_dev_urandom.php
new file mode 100644
index 000000000..db93b0757
--- /dev/null
+++ b/include/random_compat/random_bytes_dev_urandom.php
@@ -0,0 +1,148 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+if (!defined('RANDOM_COMPAT_READ_BUFFER')) {
+    define('RANDOM_COMPAT_READ_BUFFER', 8);
+}
+
+/**
+ * Unless open_basedir is enabled, use /dev/urandom for
+ * random numbers in accordance with best practices
+ * 
+ * Why we use /dev/urandom and not /dev/random
+ * @ref http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers
+ * 
+ * @param int $bytes
+ * 
+ * @throws Exception
+ * 
+ * @return string
+ */
+function random_bytes($bytes)
+{
+    static $fp = null;
+    /**
+     * This block should only be run once
+     */
+    if (empty($fp)) {
+        /**
+         * We use /dev/urandom if it is a char device.
+         * We never fall back to /dev/random
+         */
+        $fp = fopen('/dev/urandom', 'rb');
+        if (!empty($fp)) {
+            $st = fstat($fp);
+            if (($st['mode'] & 0170000) !== 020000) {
+                fclose($fp);
+                $fp = false;
+            }
+        }
+
+        if (!empty($fp)) {
+            /**
+             * stream_set_read_buffer() does not exist in HHVM
+             * 
+             * If we don't set the stream's read buffer to 0, PHP will
+             * internally buffer 8192 bytes, which can waste entropy
+             * 
+             * stream_set_read_buffer returns 0 on success
+             */
+            if (function_exists('stream_set_read_buffer')) {
+                stream_set_read_buffer($fp, RANDOM_COMPAT_READ_BUFFER);
+            }
+            if (function_exists('stream_set_chunk_size')) {
+                stream_set_chunk_size($fp, RANDOM_COMPAT_READ_BUFFER);
+            }
+        }
+    }
+
+    try {
+        $bytes = RandomCompat_intval($bytes);
+    } catch (TypeError $ex) {
+        throw new TypeError(
+            'random_bytes(): $bytes must be an integer'
+        );
+    }
+
+    if ($bytes < 1) {
+        throw new Error(
+            'Length must be greater than 0'
+        );
+    }
+
+    /**
+     * This if() block only runs if we managed to open a file handle
+     * 
+     * It does not belong in an else {} block, because the above 
+     * if (empty($fp)) line is logic that should only be run once per
+     * page load.
+     */
+    if (!empty($fp)) {
+        $remaining = $bytes;
+        $buf = '';
+
+        /**
+         * We use fread() in a loop to protect against partial reads
+         */
+        do {
+            $read = fread($fp, $remaining); 
+            if ($read === false) {
+                /**
+                 * We cannot safely read from the file. Exit the
+                 * do-while loop and trigger the exception condition
+                 */
+                $buf = false;
+                break;
+            }
+            /**
+             * Decrease the number of bytes returned from remaining
+             */
+            $remaining -= RandomCompat_strlen($read);
+            $buf .= $read;
+        } while ($remaining > 0);
+        
+        /**
+         * Is our result valid?
+         */
+        if ($buf !== false) {
+            if (RandomCompat_strlen($buf) === $bytes) {
+                /**
+                 * Return our random entropy buffer here:
+                 */
+                return $buf;
+            }
+        }
+    }
+
+    /**
+     * If we reach here, PHP has failed us.
+     */
+    throw new Exception(
+        'Error reading from source device'
+    );
+}
diff --git a/include/random_compat/random_bytes_libsodium.php b/include/random_compat/random_bytes_libsodium.php
new file mode 100644
index 000000000..f802d4e12
--- /dev/null
+++ b/include/random_compat/random_bytes_libsodium.php
@@ -0,0 +1,86 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/**
+ * If the libsodium PHP extension is loaded, we'll use it above any other
+ * solution.
+ *
+ * libsodium-php project:
+ * @ref https://github.com/jedisct1/libsodium-php
+ *
+ * @param int $bytes
+ *
+ * @throws Exception
+ *
+ * @return string
+ */
+function random_bytes($bytes)
+{
+    try {
+        $bytes = RandomCompat_intval($bytes);
+    } catch (TypeError $ex) {
+        throw new TypeError(
+            'random_bytes(): $bytes must be an integer'
+        );
+    }
+
+    if ($bytes < 1) {
+        throw new Error(
+            'Length must be greater than 0'
+        );
+    }
+
+    /**
+     * \Sodium\randombytes_buf() doesn't allow more than 2147483647 bytes to be
+     * generated in one invocation.
+     */
+    if ($bytes > 2147483647) {
+        $buf = '';
+        for ($i = 0; $i < $bytes; $i += 1073741824) {
+            $n = ($bytes - $i) > 1073741824
+                ? 1073741824
+                : $bytes - $i;
+            $buf .= \Sodium\randombytes_buf($n);
+        }
+    } else {
+        $buf = \Sodium\randombytes_buf($bytes);
+    }
+
+    if ($buf !== false) {
+        if (RandomCompat_strlen($buf) === $bytes) {
+            return $buf;
+        }
+    }
+
+    /**
+     * If we reach here, PHP has failed us.
+     */
+    throw new Exception(
+        'Could not gather sufficient random data'
+    );
+}
diff --git a/include/random_compat/random_bytes_libsodium_legacy.php b/include/random_compat/random_bytes_libsodium_legacy.php
new file mode 100644
index 000000000..44fddbf6f
--- /dev/null
+++ b/include/random_compat/random_bytes_libsodium_legacy.php
@@ -0,0 +1,86 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/**
+ * If the libsodium PHP extension is loaded, we'll use it above any other
+ * solution.
+ *
+ * libsodium-php project:
+ * @ref https://github.com/jedisct1/libsodium-php
+ *
+ * @param int $bytes
+ *
+ * @throws Exception
+ *
+ * @return string
+ */
+function random_bytes($bytes)
+{
+    try {
+        $bytes = RandomCompat_intval($bytes);
+    } catch (TypeError $ex) {
+        throw new TypeError(
+            'random_bytes(): $bytes must be an integer'
+        );
+    }
+
+    if ($bytes < 1) {
+        throw new Error(
+            'Length must be greater than 0'
+        );
+    }
+
+    /**
+     * \Sodium\randombytes_buf() doesn't allow more than 2147483647 bytes to be
+     * generated in one invocation.
+     */
+    if ($bytes > 2147483647) {
+        $buf = '';
+        for ($i = 0; $i < $bytes; $i += 1073741824) {
+            $n = ($bytes - $i) > 1073741824
+                ? 1073741824
+                : $bytes - $i;
+            $buf .= Sodium::randombytes_buf($n);
+        }
+    } else {
+        $buf = Sodium::randombytes_buf($bytes);
+    }
+
+    if ($buf !== false) {
+        if (RandomCompat_strlen($buf) === $bytes) {
+            return $buf;
+        }
+    }
+
+    /**
+     * If we reach here, PHP has failed us.
+     */
+    throw new Exception(
+        'Could not gather sufficient random data'
+    );
+}
diff --git a/include/random_compat/random_bytes_mcrypt.php b/include/random_compat/random_bytes_mcrypt.php
new file mode 100644
index 000000000..7ac9d9105
--- /dev/null
+++ b/include/random_compat/random_bytes_mcrypt.php
@@ -0,0 +1,76 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+
+/**
+ * Powered by ext/mcrypt (and thankfully NOT libmcrypt)
+ * 
+ * @ref https://bugs.php.net/bug.php?id=55169
+ * @ref https://github.com/php/php-src/blob/c568ffe5171d942161fc8dda066bce844bdef676/ext/mcrypt/mcrypt.c#L1321-L1386
+ * 
+ * @param int $bytes
+ * 
+ * @throws Exception
+ * 
+ * @return string
+ */
+function random_bytes($bytes)
+{
+    try {
+        $bytes = RandomCompat_intval($bytes);
+    } catch (TypeError $ex) {
+        throw new TypeError(
+            'random_bytes(): $bytes must be an integer'
+        );
+    }
+
+    if ($bytes < 1) {
+        throw new Error(
+            'Length must be greater than 0'
+        );
+    }
+
+    $buf = @mcrypt_create_iv($bytes, MCRYPT_DEV_URANDOM);
+    if (
+        $buf !== false
+        &&
+        RandomCompat_strlen($buf) === $bytes
+    ) {
+        /**
+         * Return our random entropy buffer here:
+         */
+        return $buf;
+    }
+
+    /**
+     * If we reach here, PHP has failed us.
+     */
+    throw new Exception(
+        'Could not gather sufficient random data'
+    );
+}
diff --git a/include/random_compat/random_int.php b/include/random_compat/random_int.php
new file mode 100644
index 000000000..fd3ef87a2
--- /dev/null
+++ b/include/random_compat/random_int.php
@@ -0,0 +1,191 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/**
+ * Fetch a random integer between $min and $max inclusive
+ * 
+ * @param int $min
+ * @param int $max
+ * 
+ * @throws Exception
+ * 
+ * @return int
+ */
+function random_int($min, $max)
+{
+    /**
+     * Type and input logic checks
+     * 
+     * If you pass it a float in the range (~PHP_INT_MAX, PHP_INT_MAX)
+     * (non-inclusive), it will sanely cast it to an int. If you it's equal to
+     * ~PHP_INT_MAX or PHP_INT_MAX, we let it fail as not an integer. Floats 
+     * lose precision, so the <= and => operators might accidentally let a float
+     * through.
+     */
+    
+    try {
+        $min = RandomCompat_intval($min);
+    } catch (TypeError $ex) {
+        throw new TypeError(
+            'random_int(): $min must be an integer'
+        );
+    }
+
+    try {
+        $max = RandomCompat_intval($max);
+    } catch (TypeError $ex) {
+        throw new TypeError(
+            'random_int(): $max must be an integer'
+        );
+    }
+    
+    /**
+     * Now that we've verified our weak typing system has given us an integer,
+     * let's validate the logic then we can move forward with generating random
+     * integers along a given range.
+     */
+    if ($min > $max) {
+        throw new Error(
+            'Minimum value must be less than or equal to the maximum value'
+        );
+    }
+
+    if ($max === $min) {
+        return $min;
+    }
+
+    /**
+     * Initialize variables to 0
+     * 
+     * We want to store:
+     * $bytes => the number of random bytes we need
+     * $mask => an integer bitmask (for use with the &) operator
+     *          so we can minimize the number of discards
+     */
+    $attempts = $bits = $bytes = $mask = $valueShift = 0;
+
+    /**
+     * At this point, $range is a positive number greater than 0. It might
+     * overflow, however, if $max - $min > PHP_INT_MAX. PHP will cast it to
+     * a float and we will lose some precision.
+     */
+    $range = $max - $min;
+
+    /**
+     * Test for integer overflow:
+     */
+    if (!is_int($range)) {
+
+        /**
+         * Still safely calculate wider ranges.
+         * Provided by @CodesInChaos, @oittaa
+         * 
+         * @ref https://gist.github.com/CodesInChaos/03f9ea0b58e8b2b8d435
+         * 
+         * We use ~0 as a mask in this case because it generates all 1s
+         * 
+         * @ref https://eval.in/400356 (32-bit)
+         * @ref http://3v4l.org/XX9r5  (64-bit)
+         */
+        $bytes = PHP_INT_SIZE;
+        $mask = ~0;
+
+    } else {
+
+        /**
+         * $bits is effectively ceil(log($range, 2)) without dealing with 
+         * type juggling
+         */
+        while ($range > 0) {
+            if ($bits % 8 === 0) {
+               ++$bytes;
+            }
+            ++$bits;
+            $range >>= 1;
+            $mask = $mask << 1 | 1;
+        }
+        $valueShift = $min;
+    }
+
+    /**
+     * Now that we have our parameters set up, let's begin generating
+     * random integers until one falls between $min and $max
+     */
+    do {
+        /**
+         * The rejection probability is at most 0.5, so this corresponds
+         * to a failure probability of 2^-128 for a working RNG
+         */
+        if ($attempts > 128) {
+            throw new Exception(
+                'random_int: RNG is broken - too many rejections'
+            );
+        }
+
+        /**
+         * Let's grab the necessary number of random bytes
+         */
+        $randomByteString = random_bytes($bytes);
+        if ($randomByteString === false) {
+            throw new Exception(
+                'Random number generator failure'
+            );
+        }
+
+        /**
+         * Let's turn $randomByteString into an integer
+         * 
+         * This uses bitwise operators (<< and |) to build an integer
+         * out of the values extracted from ord()
+         * 
+         * Example: [9F] | [6D] | [32] | [0C] =>
+         *   159 + 27904 + 3276800 + 201326592 =>
+         *   204631455
+         */
+        $val = 0;
+        for ($i = 0; $i < $bytes; ++$i) {
+            $val |= ord($randomByteString[$i]) << ($i * 8);
+        }
+
+        /**
+         * Apply mask
+         */
+        $val &= $mask;
+        $val += $valueShift;
+
+        ++$attempts;
+        /**
+         * If $val overflows to a floating point number,
+         * ... or is larger than $max,
+         * ... or smaller than $min,
+         * then try again.
+         */
+    } while (!is_int($val) || $val > $max || $val < $min);
+
+    return (int) $val;
+}