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{ Category Archives } Security

Use /dev/random Instead Of /dev/null

While writing a shell script the other day, I was redirecting some output to /dev/null, as normal, when something dawned on me. Why don't I redirect my output to /dev/random instead? After all, both Linux random devices are writable by everyone on the system: $ ls -l /dev/*random crw-rw-rw- 1 root root 1, 8 Nov […]

The Bitmessage Proof Of Work

I've been on the Bitmessage network roughly since it was released. Maybe only a month or two later. One thing that has had me intrigued, although I've never really paid attnetion to ut until now, is Bitmessage's proof-of-work puzzle. A proof-of-work puzzle is a puzzle your computer solves to generally gain access to some resource. […]

Using The Bitmessage Storage Service

While hanging out on the "privacy" channel on Bitmessage, someone sent the following: "You have no files saved. For instructions please send a message to BM-2cUqBbiJhTCQsTeocfocNP5WCRcH28saPU with the subject 'help'." This is actually pretty cool. No doubt should you call into question a faceless storage provider, but I thought I would play around with it. […]

Where Cryptographic Hashing Algorithms Fail

What Is A Cryptographic Hashing Algorithm? Cryptographic hashing algorithms are one-way functions that produce a message digest that represents a given input. Because the keyspace is so astromically large, it should be practically infeasible to find a different input that represents the same digest. The input is typically referred to as the message while the […]

Cryptographically Secure Pseudorandom Locally Administered Unicast MAC Addresses

Recently, Apple released the ability for iPhone 5c and newer hardware to create a spoofed software MAC address for 2.4 GHz and 5 GHz wireless access points. The MAC address is locally administered, and a unicast address. This has sparked a small discussion in various forums about how to generate valid locally administered unicast MAC […]

Talon

I've been obsessing over the past couple weeks trying to improve Bruce Schneier's solitaire cipher, aka "Pontifex". The more I think about it, the more I realize that there just isn't a lot that can be done about the bias of Pontifex without severely slowing down the already slow algorithm. So, instead of trying to […]

What's The Matter With PGP?

http://blog.cryptographyengineering.com/2014/08/whats-matter-with-pgp.html has been making its way around crypto circles recently. Enough so, that I figured I would comment by posting a reply on my own blog. This post is written by cryptographer Matthew D. Green. As a result, even though I've never heard of Dr. Green, when I read the post, I was expecting something […]

The Linux Random Number Generator

Introduction There is a lot of misinformation out there about /dev/random and /dev/urandom with regards to the Linux kernel. Unfortunately, not even the random(4) manpage seems to get it right. So, rather than argue with everyone on the Internet, I'll post the inner workings of the Linux kernel with respect to randomness here. TL;DR If […]

Tor Versus Road Warrior

Lately, I have been doing some research regarding Tor, and the technology behind it. Further, I wanted to compare it to other products such as Freenet and I2P. In the process, I stumbled upon this post regarding comparing Tor to a proprietary product called "Road Warrior" from a company called "Cryptohippie". Initially, I tried commenting […]

Cryptographically Secure Passphrases In d-note

A couple nights ago, while coming home from work, I started thinking about the button you press on the d-note web application (an instance running at https://secrets.xmission.com) for generating passphrases used to encrypt your note. Each passphrase is a 22-character base 64 passphrase. Initially, I was using the following code in JavaScript: 123456789function make_key() { […]

Officially Announcing d-note Version 1.0

I've been looking forward to this post. Finally, on my birthday, it's here. My Python Flask web application of encrypted self-destructing notes is stable, and ready for production use. History Around 2011, or so, I started thinking about a way that I could send data privately and securely to friends, family and coworkers, without requiring […]

Analysis of RIPEMD-160

Recently on Hacker News, I noticed a table showing the "Life cycles of popular cryptographic hashes" by Valerie Aurora (in this post, I've greatly compressed her HTML for faster page delivery). Life cycles of popular cryptographic hashes (the "Breakout" chart) Function 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 […]

SHA3 (Keccak) in Linux

For a long time, I've been waiting to use the newly accepted SHA3 in Linux for file integrity and other uses. Like the md5sum(1), sha1sum(1), sha224sum(1), sha256sum(1), sha384sum(1), and sha512sum(1), I was hoping that a similar "sha3-224sum(1)", etc would be developed, and make its way into the GNU/Linux library. Unfortunately, I kept waiting and waiting, […]

The Drunken Bishop For OpenPGP Keys

Almost a year ago, I blogged about the drunken bishop algorithm for OpenSSH key random art. Towards the end of the post, I mentioned that I would be building an OpenPGP implementation. I started doing so in Python, but eventually got sidetracked with other things. Well, I hosted the Scale 12x PGP keysigning party, and […]

Time Based One Time Passwords - How It Works

Introduction With all the news about Heartbleed, passwords, and two-factor authentication, I figured I would blog about exactly how two-factor authentication can work- in this case, TOTP, or Time based one time passwords, as defined by The Initiative for Open Authentication (OATH). TOTP is defined in RFC 6238, and is an open standard, which means […]