FlipEndian.sol

pragma solidity ^0.4.19;
contract FlipEndian {

    function flip32_1(bytes32 a) public constant returns (bytes32 b){
        assembly {
            0
            and(div(a, 0x100000000000000000000000000000000000000000000000000000000000000), 0xFF)
            or
            and(div(a, 0x10000000000000000000000000000000000000000000000000000000000), 0xFF00)
            or

holiman

contract complex{
	address add;
	uint aa;
	uint bb;

	function thrower()
	{
		throw;
	}

alexvandesande

contract random {
    /* Generates a random number from 0 to 100 based on the last block hash */
    function randomGen(uint seed) constant returns (uint randomNumber) {
        return(uint(sha3(block.blockhash(block.number-1), seed ))%100);
    }

    /* generates a number from 0 to 2^n based on the last n blocks */
    function multiBlockRandomGen(uint seed, uint size) constant returns (uint randomNumber) {
        uint n = 0;
        for (uint i = 0; i < size; i++){

karlgluck

What's this all about?

Digital cryptography! This is a subject I've been interested in since taking a class with Prof. Fred Schneider back in college. Articles pop up on Hacker News fairly often that pique my interest and this technique is the result of one of them.

Specifically, this is about Lamport signatures. There are many signature algorithms (ECDSA and RSA are the most commonly used) but Lamport signatures are unique because they are formed using a hash function. Many cryptographers believe that this makes them resistant to attacks made possible by quantum computers.

How does a Lamport Signature work?