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for BYOS? The answer to that question depends on how likely it is the employer will suffer from one of the disadvantages. Because those are also considerable.

The lack of uniformity and overview makes it challenging to effectively protect critical business information and client data. Stuck in a maze of different software applications, it is very difficult to know whether or not you meet the legal obliga-tions of compliance. Linked to this is the lack of possibilities for auditing. Since the company itself is not a buyer of the software, it cannot hold the supplier liable in case of malfunction. Due to deficient overview of the applications that are used by employees, it is next to impossible to be sure all patches and updates have been installed and the network is secure.

If the IT support staff of the company want to be able to help all employees with occurrences of IT problems, they would need to learn all the ins and outs of all possible software applications. Another point is the almost certain scenario that different applications are not compatible with one another and will cause crashes and other failures. And since the PRISM news story broke, many European busi-nesses do not want to use US software providers for security sensitive tasks such as cloud storage and anti-virus. All US companies are subject to the Patriot Act, and so are required to share information from and about their customers with secret services and other state anti-terror-ist agencies when called upon. Keeping US suppliers out of the IT network is not easy when handling a BYOS policy.

What will it be? The benefits of a policy that allows employees the freedom to work with tools they like to work with are big. Employees feel trusted and they can do their job quicker and hopefully better. Even if their time saving is lost in a subsequent process of translation or adaptation of the output files, happy employees are worth a lot. However, when the disadvantages are so severe that almost any one of them can end your entire business venture, the issues cannot be discarded very easily. So choosing a BYOS policy does not seem like a good idea at this point.

Should we move back in time and put our employees on a ball and chain? Not necessarily. There is a happy medium, though it can cost a lot of time:

employees in different departments might want to use and make sure they offer a high compatibility with other applications that will be on the net-work.

of software employees can choose from.

all updates and patches of all this software, so you can be in control of patch management.

-sen policy and agree with it, to make sure they will abide by it. It is also possible to enforce compliance to the policy in a technical way with a policy manager.

wishes of employees and make sure the software range you offer is updat-ed regularly.

Within such a framework, BYOS can be transformed into CYOS (Choose Your Own Software), a more realistic, and at the same time flexible, approach, that benefits both the efficiency and the employee’s happiness.

About the authorDaniëlle van Leeuwen is PR manager UK and Benelux at the German IT security provider G Data Software. She studied communication and information sciences at the Vrije Universiteit Amsterdam. She started her career as a PR consultant at a PR agency specialised in IT. In 2009 she joined G Data Software as an in-house PR consultant. In this role, she has learned the ins and outs of the industry and has writ-ten and co-written countless articles, white-papers, reports, blog posts and opinion pieces on many different IT security topics.

References1. ‘Q1 BYOD Smartphone Sales Surge

in North America and Asia but Western Europe Fights Growing Trend’. Strategy Analytics, 13 Jun 2013. Accessed Mar 2014. www.strat-egyanalytics.com/default.aspx?mod=pressreleaseviewer&a0=5376.

2. Dvorak, John. ‘BYOD should includes BYOS’. PCMag.com, 1 May 2013. Accessed Mar 2014. http://www.pcmag.com/article2/0,2817,2418427,00.asp.

3. Datanews, nr 12, 21 Jun 2013.

Can we make email secure?

Danny BradburyDanny Bradbury

Email has always been insecure. When it was first developed, openness and col-laboration were necessary just to develop the nascent networks that eventually formed the Internet, and to keep them operational. But while that Internet has since evolved into a nasty tangle of threats and malicious behaviour, email has lagged behind. It is still insecure, and users risk multiple attacks. This year, attention was drawn to the specific privacy threats surrounding email. The

Newsworthy dangersEmail surveillance has always been a danger, but in late 2013, it has been particularly newsworthy, thanks in part to government whistleblower Edward

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Snowden, and Lavabit. Snowden used Lavabit, a provider of secure email ser-vices, for private communications. Emails were encrypted on the system, but the US Government demanded that the company hand over its encryption keys. Lavabit founder Lavar Levison shut down his ser-vice to try and avoid government interfer-ence, and appealed the request.1,2

Silent Circle, another private email ser-vice, also shuttered its service, explicitly cit-ing Lavabit’s closure as “the writing on the wall”.3 “Email that uses standard Internet protocols cannot have the same security guarantees that real-time communications has,” explained Silent Circle co-founder and CTO Jon Callas. “There are far too many leaks of information and metadata intrinsically in the email protocols them-selves. Email as we know it with SMTP, POP3 and IMAP cannot be secure.”

Then, 11 days later, Groklaw shut down. The website, which had for years reported on legal issues relating to the free open source software (FOSS) community, announced on 20 Aug 2013 that it would be closing its doors.4 “They tell us that if you send or receive an email from outside the US, it will be read,” said the site’s operator, Pamela Jones. “If it’s encrypted, they keep it for five years, presumably in the hopes of tech advancing to be able to decrypt it against your will and without your knowledge. Groklaw has readers all over the world.”

Jones added that Lavabit’s founder had warned: if we knew what he knew about email, we wouldn’t be using it either. What’s going on here, and why is con-ventional email so vulnerable?

There are two broad privacy vulner-abilities associated with conventional email: the vulnerability of the email’s content (which is normally transmitted in plain text), and the metadata that can be derived from the email’s header. Each of these vulnerability types stems from the way that emails are constructed and sent. That process relies mostly on the Simple Mail Transfer Protocol (SMTP).

How email worksTo understand why SMTP is so inse-cure, it’s worth reviewing how it works. Email clients are designed to send mes-

sages using the SMTP protocol, and must specify an SMTP server to accept the message (this will generally be the sender’s email service provider).

The SMTP server reads the SMTP header sent as part of the email and works out whether it also has an account for the intended recipient. If so, it is delivered to that user’s inbox. If the SMTP server doesn’t have an account for that user, it is instead relayed to another SMTP server, which then goes through the same process.

The relaying process uses mail exchange (MX) records, which contain a list of host names that should accept SMTP mail.5 An SMTP server will look up the name servers for an email recipient’s domain, and will ask them for the MX records associated with that domain. Armed with that information, it can send the information to that server and have it deliver the email address. However, if an MX record doesn’t con-tain the right host details, it will forward the message to another that does. That can result in hops through a number of intermediate relay or gateway hosts.6

Emails are usually formatted in plain text, using the Multipurpose Internet Mail Extension (MIME) standard, which means that they can be intercept-ed and read anywhere along the way.

SMTP servers send the message header and the content together, generally in clear

text. Several steps have been taken to secure the content, namely Phil Zimmerman’s Pretty Good Privacy (PGP) and derivatives thereof, which uses digital certificates to encrypt the content of emails. These certifi-cates are created and certified by a web of trust, in which people within a community attest to each other’s identities.7

S/MIME, another content encryption option, is an extension to SMTP that enables users to scramble their content, often using a single button within a com-patible email client. However, these sys-tems are not universally (if even widely) used, and in any case they don’t solve the other major vulnerability inherent in SMTP: metadata analysis.

Meet your metadataThe metadata in an SMTP header pro-vides useful information about the sender. It provides a sender IP address, which can be queried to find everything from geo-graphic location, to the IP owner’s address and other details. Reverse lookups can provide information about the computer in question (and this also be derived from information about the email software used by the sender, which is included in the header). Online research tools can yield information about other email addresses used on that IP, and insights into the user’s other online activities.8

How email works. Source: Yzmo.

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The sender’s time zone and native lan-guage can also be derived from the SMTP information, as can their ISP.

Mail systems need not always relay across the open Internet, of course. Centralised email systems, in which users all subscribe to the same service, enable senders to get messages to each other with-out leaving a trail on the open Internet. Surely these services can still be secure?

Retrieval of data from centralised email services – whether via subpoenas or worse – can be a problem. The NSA’s PRISM program revealed by Edward Snowden reportedly enabled US authori-ties to systematically access information about customers from the systems of large online service providers. Microsoft, for example, was found to have given the FBI’s Data Intercept Unit pre-encryption access to emails on Outlook.com and Hotmail.com.9

Some secure email services may offer bulletproof, encrypted services, but just how secure they are depends on how they’re configured. Encryption keys alone don’t make a service secure. Lavabit secured messages using a clear text public key and a private key, the latter of which was AES-256 encrypted using a password provided by the user. The service didn’t have the capability to decrypt the pass-words, but Lavabit did store the encrypt-ed keys on its servers.10 That meant that if the authorities gain access to those keys, they could potentially decrypt that user’s mails on the firm’s servers.

Other supposedly secure services have happily handed over customer emails, even after promising that they didn’t have access. In 2007, Canadian firm Hushmail turned over 12 CDs of emails from three accounts, accessed via its webmail service.11

Proposed alternativesVarious alternatives have been proposed to try and make email more secure, and they all take different approaches. One, Deutsche Telekom and United Internet’s ‘Email made in Germany’ initiative, promises that emails will be forwarded between the three in encrypted form, to avoid interception.12

However, the scheme has come under fire from German hacking group the

Chaos Computer Club (CCC). Data transmitted through German ISPs is subject to the EU’s data retention law, which requires service providers to retain customer data for up to two years. The European Data Protection Supervisor has said that this “clearly constitutes an interference with the right to privacy of the persons concerned”.13

“The problem of clear text SMTP headers still remains, and consumers are unlikely to want to host their own email servers, even if the capability is build into the software”

Some prefer the idea of running their own mail servers. Icelandic pro-ject Mailpile, which has received over $160,000 in crowdfunded donations, aims to create an open source mail cli-ent with built-in support for OpenPGP and S/MIME encryption. Although it will initially be designed to connect to SMTP servers, it may eventually include its own SMTP server capabilities, say the team behind it.14

This is a laudable effort, which will encourage people to run their own email servers in the longer-term, and could at least encourage end-to-end encryption among users of the same server, but there are challenges, still. The problem of clear text SMTP headers still remains, and con-sumers are unlikely to want to host their own email servers, even if the capability is build into the software. It is difficult to see how different this would be from using an open-source mail program such as Thunderbird, and a Linux-based mail server in a closet.

Bitcoin and messaging meetOther ideas take a completely different approach, using entirely decentralised and encrypted networks to send and receive messages. One such system is BitMessage, a peer-to-peer commu-nications protocol that uses the same proof-of-work concept as the Bitcoin digital currency system.15 Users must make a computational investment (typi-cally about four minutes of CPU time)

to send a message, and it is delivered to everyone in the network. Only the intended recipient of the message is able to decode the message, which has been encrypted using their private key.

This system carries some significant upsides. It makes one-many broadcasts relatively easy, because people can sub-scribe to messages from a particular address. But it also discourages spam, because there is a computational over-head in sending messages.

It also carries some challenges, notably around ease of use. Bitmessage addresses, like Bitcoin addresses, are long, incom-prehensible alphanumeric strings. The lack of a human-readable message for-mat is both a blessing (it’s difficult if not impossible to track an address to a particular organisation) and a curse (the addresses are counter-intuitive).

The system faces scalability challenges, too – although the designers attempt to address these by segregating the P2P net-work. And – perhaps most importantly – it isn’t compatible with the existing email system. In short, it’s a form of closeted asynchronous messaging for geeks, mean-ing that participants in a conversation must have a prior relationship, and must all agree to – and make the cognitive investment – in using it.

Dark MailWhile these options continue to circulate, the people behind Lavabit and Silent Circle have not been idle. In November, they launched a project called Dark Mail, designed to adopt a new approach to email by doing away with SMTP alto-gether and replacing it with an exchange protocol based on the Extensible Messaging and Presence Protocol (XMPP) – an XML-based messaging pro-tocol originally known as Jabber.16 This is significant, because XMPP supports text chat/instant messaging-type dialogues, too, and is flexible. Silent Circle main-tains other services that focus on these types of messages.

One of the key features of Dark Mail is that it will eliminate the message header, replacing it with minimal routing infor-mation. The XMPP-based routing system will run on Dark Mail servers operated by

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third parties. There’s no reason why you couldn’t run a Dark Mail compatible cli-ent and server on your laptop.

“There is no reason why a sender can’t talk to a recipient’s server without getting intermediate servers involved – in the future, it may be possible in some cases to simply communicate between individual devices”

Headers won’t exist, says Callas. “We’re simply going to get rid of them”. The server has to know who the user is, and where they are, if they are off the mail server’s domain.

The IP address is all that’s exposed, he says. “That you can’t hide.” Even VPNs and Tor need those, he points out. If users wanted true anonymity, cloaking even that information, they’d have to use an anonymising layer like the Tor network, according to Callas. He ima-gines someone producing a client with a built-in Tor connection, for example. There is no reason why a sender can’t talk to a recipient’s server without get-ting intermediate servers involved, says Callas, adding that in the future, it may be possible in some cases to simply com-municate between individual devices.

The open source protocol will sepa-rate the routing information logically from the content, to the extent that one provider could handle the storage and one could do the routing. Both will be encrypted, providing end-to-end security on both the routing and the messages themselves, says Callas. Separating the storage from the routing also improves performance, he argues.

All of the encryption keys are generat-ed on the endpoint, and the servers don’t know about them at all. Dark Mail will use its own encrypted instant message-like protocol for the routing, and then AES “or equivalent” encryption for the content stream. The system will use an adaptor, so that a message sent to some-one using traditional SMTP systems will be converted. This will make it secure inside the Dark Mail network, while supporting traditional users.

There are still challenges. Dark Mail servers will still use the Domain Naming System (DNS). This service itself has its problems, which allow spoofing and poisoning attacks, but Callas argues that people have to solve one small problem at a time.

It is difficult to ascertain exactly how secure Dark Mail will be until a white paper appears, and early versions of the protocol are made available. But in attempting to build a secure messaging system from the ground up, the team at least has a chance to learn from past mistakes. Whether or not it will stop those annoying phishing emails from shady actors in the former eastern bloc, however, remains to be seen.

About the authorDanny Bradbury is a technology write with 25 years of experience. He writes regularly about subjects ranging from security to digi-tal currency. He has worked for publications ranging from the Guardian, through to the Economist Intelligence Unit, and Canada’s National Post newspaper. He lives in Vancouver.

References1. Lavar Levison, Closing down notice,

Lavabit. Accessed Feb 2014. http://lavabit.com/.

2. Alex Hearn. ‘Edward Snowden email provider Lavabit appeals against state intrusion’. The Guardian, 11 Oct 2013. Accessed Feb 2014. www.theguardian.com/technology/2013/oct/11/edward-snowdens-lavabit-appeals-government-intrusion.

3. Jon Callas. ‘To Our Customers’. Silent Circle Blog, 9 Aug 2013. Accessed Feb 2014. http://silentcir-cle.wordpress.com/2013/08/09/to-our-customers/.

4. Pamela Jones. ‘Forced Exposure’. Groklaw, 20 Aug 2013. Accessed Feb 2014. www.groklaw.net/article.php?story=20130818120421175.

5. ‘How MX Records Work’. Google, accessed Nov 2013. www.google.com/support/enterprise/static/postini/docs/admin/en/activate/mx_faq.html.

6. Simple Mail Transfer Protocol Draft Standard, IETF, Oct 2008. Accessed Feb 2014. http://tools.ietf.org/html/rfc5321.

7. ‘Introduction to Cryptography’. Official PGP website. Accessed Nov 2013 www.pgpi.org/doc/pgpintro/#p17.

8. ‘What an IP Address Can Reveal About You’. Privacy Commissioner of Canada, May 2013. Accessed Feb 2014. www.priv.gc.ca/infor-mation/research-recherche/2013/ip_201305_e.asp.

9. Glenn Greenwald, Ewen MacAskill, Laura Poitras, Spencer Ackerman, Dominic Rushe. ‘Microsoft handed the NSA access to encrypted mes-sages’. The Guardian, 12 July 2013. Accessed Feb 2014. www.theguard-ian.com/world/2013/jul/11/micro-soft-nsa-collaboration-user-data.

10. ‘Security through Asymmetric Encryption’. Lavabit (archived), accessed Nov 2013. http://web.archive.org/web/20130403130706/http:/lavabit.com/secure.html.

11. Ryan Singel. ‘Encrypted Email Company Hushmail Spills to Feds’. Wired, 7 Nov 2007. Accessed Feb 2014. www.wired.com/threatlev-el/2007/11/encrypted-e-mai/.

12. ‘Deutsche Telekom, WEB.DE and GMX launch “Email made in Germany” initiative’. Deutsche Telekom, Aug 8 2013. Accessed Feb 2014. www.telekom.com/media/company/192834.

13. ‘Opinion of the European Data Protection Supervisor on the Evaluation report from the Commission to the Council and the European Parliament on the Data Retention Directive (Directive 2006/24/EC)’. European Data Protection Supervisor, May 2011. Accessed Feb 2014. https://secure.edps.europa.eu/EDPSWEB/webdav/site/mySite/shared/Documents/Consultation/Opinions/2011/11-05-30_Evaluation_Report_DRD_EN.pdf.

14. Mailpile, Indiegogo website. Accessed Nov 2013. www.indiegogo.com/pro-jects/mailpile-taking-email-back.

15. Bitmessage website. Accessed Nov 2013. https://bitmessage.org/wiki/Main_Page.

16. Dark Mail website. Accessed Nov 2013. http://darkmail.info/.