defuse

<?php

/*
 * Padding oracle attack against https://github.com/keboola/php-encryption
 * By: Taylor Hornby.
 * Date: March 14, 2014.
 */

/* Download the two files and place in the same folder. */
require_once('EncryptorInterface.php');

defuse

<?php
// Broken crypto code from https://github.com/slimphp/Slim/blob/develop/Slim/Crypt.php
function validateKeyLength($key, $module)
    {
        $keySize = strlen($key);
        $keySizeMin = 1;
        $keySizeMax = mcrypt_enc_get_key_size($module);
        $validKeySizes = mcrypt_enc_get_supported_key_sizes($module);
        if ($validKeySizes) {
            if (!in_array($keySize, $validKeySizes)) {

defuse

<?php

/*
 * Backdooring the constant-time comparison algorithm.
 * Taylor Hornby. Feburary 28, 2015.
 *
 * THIS CODE IS INTENTIONALLY BACKDOORED. DO NOT USE IT!
 */

/* ========================================================================= */

defuse

  George Carlin                                            INVOICE
  carlin@example.org

  To:                                                   Invoice #6
      Stephen Hawking                         Date:   May 13, 2014
      hawking@example.org

  +-----------------------------------------------------------------+
  | Quantity |         Description         | Unit Price |   Total   |

defuse

// WARNING! This code is untested and experimental. DO NOT USE IT.

// NOTE: If I knew of a way to do the "shift and OR" thing reliably with unsigned ints, the code could be simplified a lot.

// Will always be compiled with -std=c99

// Returns UINT32_MAX if a == b, 0 otherwise.
uint32_t invariant_time_integer_compare(uint32_t a, uint32_t b)
{
    /* z will be zero if and only if a == b. */

defuse

# This is well-known behavior, it's just interesting.
$ mkdir a
$ echo "hello!" > a/file.txt
$ cat a/file.txt
hello!
$ chmod 000 a/file.txt 
# Now I don't expect to be able to change a/file.txt...
$ echo "GOODBYE" > a/file.txt
bash: a/file.txt: Permission denied
# Okay, good, I can't modify the file directly.

defuse

WARNING: This takes about 10-20 hours to run, depending on your system.
1%...
2%...
3%...
4%...
5%...
6%...
7%...
8%...
9%...

defuse

Goal: 
    You're given a sequence of random alphanumeric characters (0-9a-zA-Z, 62
    possible characters), for example from a password generator. Convert it into
    a sequence of random *bits*.

    The output should have the property:

        The alphanumeric character RNG can be distinguished from random if and
        only if the alphanumeric character RNG, with the conversion algorithm
        attached, can be distinguished from random.

defuse

# WARNING! There is no warranty. This script might not work!

FILE = "Download.csv"
rows = []

File.open( FILE ) do |f|
  rows = f.readlines()
end

rows = rows[1..-1]

defuse

# This script answers the following question:
# Alice chooses N random numbers between 1 and K.
# Bob chooses G random numbers between 1 and K.
# What is the probability that at least one number is chosen by both of them?

# Computes (K-N choose G) / (K choose G) in O(N)-ish time.

k = 1_000_000_000
n = 10_000
g = 100_000