Numberphile recently posted a video about the math behind RSA encryption.  In the video below, a brief description of public key cryptography is given and then we are shown a simple example of the math used to perform encryption and decryption (math example @ 2:25). In the video, James skips over the method for determining the private key, so I thought I would run through the key generation steps for his example. Choose two distinct prime numbers p and q. These are the two primes that he mentioned, so p = 2 and q = 5. Compute n = pq. Simply multiply 2 and 5. n = 10. Compute the totient of n, or (p-1)(q-1). (2-1) times (5-1) is 1[…]

My last post on the topic of S/MIME on iOS 5 got a lot of helpful comments from readers filled in the gaps left by Apple’s current lack of documentation on this topic. The previous article is still the best place for information on how to set up your device to use S/MIME. This post has more information on actually using S/MIME for encrypting email messages. Enabling S/MIME There’s a setting I missed in the previous post was pointed out by a commenter. After getting iOS 5 on the device and putting your certificates on there, you need to edit your email settings. Click Settings->Mail, Contacts, Calendars->Your email account->Account->Advanced. Scroll down to the S/MIME section and turn on S/MIME. (Note[…]

NOTE: I’ve updated this post in a few places below today, 6/13/2011, based on help from commenters. Also see the follow-up article Sending and Receiving S/MIME Encrypted Email on iOS 5 (Beta). During the 2011 Apple Worldwide Developer Conference keynote address, Scott Forstall indicated that iOS 5 would have support for S/MIME encrypted email. (Skip to 63:10 in the presentation.) This morning I successfully upgraded to the iOS 5 Beta and started being able to read my S/MIME encrypted email. Here is how I did it. What you need: –       Xcode 4.2 and iOS SDK 5 beta (requires iOS Developer Program account) –       iOS 5 beta for your iOS device’s platform (requires iOS Developer Program account) –       iTunes 10.5 beta[…]

The big news of the week, emanating from Toorcon 12, is the release of Firesheep. This tool makes SideJacking – that is, “hijacking an engaged Web session with a remote service by intercepting and using the credentials that identified the user/victim to that specific server” – painfully simple for anybody to use. How easy? Well, let’s see… you download and install Firefox… and then you download and install the Firesheep extension to Firefox… and then you restart Firefox and run the tool to start hijacking sessions… that’s it! Simple enough for ya? SideJacking is not a new concept, nor is the existence of tools. Robert Graham of Errata Security made a bit of a splash with his tool Hamster back[…]

According to a new article on TechTarget, a study by the Ponemon Institute has revealed the cost of a data breach has increased once again, to $204 per compromised record. The study is available for download at after giving away some personal details. The “Fifth Annual U.S. Cost of Data Breach Study,” funded in part by encryption vendor PGP Corp., determines the annual cost of the breach by establishing a company’s cost of lost business as a result of an incident; expenses incurred by notifying individuals and authorities of a breach; costs associated with legal fees and consulting firms and new investments made in technology and employee education. In our down economy, it is interesting that the cost of[…]

As many have noticed, Apple has released their new lineup of laptops, software, OSes, and iPhones. As I watched live coverage of the keynotes on Monday (thanks Gizmodo) – a few things caught my attention when they were speaking about the new iPhone 3G S. The first thing that caught my eye was the mention of “hardware encryption.” Now, simply mentioning that a device supports hardware encryption can mean a lot of things, and Apple isn’t very clear about what they mean by this. Trying to do some further research didn’t help much either as I only ended up being further confused with all the different mentions of this “hardware encryption.” The official word from Apple is… iPhone 3G S[…]