Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.


03:48 AM
Gadi Evron
Gadi Evron
Connect Directly

How Much Crypto You Really Need

Last month an international team of researchers announced they had managed to factor a 768-bit RSA key. This raises interesting questions about handling encryption and planning ahead in your security strategy.

Last month an international team of researchers announced they had managed to factor a 768-bit RSA key. This raises interesting questions about handling encryption and planning ahead in your security strategy.I am not a cryptographer and therefore not an authority on the RSA algorithm. However, I would like to discuss the strategic use of encryption and how that impacts our decision on choosing and implementing an encryption scheme.

In the introduction to their paper (PDF), the researchers wrote:

Because the first factorization of a 512-bit RSA modulus was reported only a decade ago (cf. [7]) it is not unreasonable to expect that 1024-bit RSA moduli can be factored well within the next decade by an academic effort such as ours or the one in [7]. Thus, it would be prudent to phase out usage of 1024-bit RSA within the next three to four years.
The researchers make it clear that this is not an immediate threat, and while the use of larger keys should be phased in, there are no immediate security ramifications.

When choosing an encryption algorithm, you must first ask yourself what your purpose is -- in other words, conduct a risk analysis. What do you want to protect? How important is it? How vulnerable is it? What is the threat? Who is the threat?

If your biggest risk is your neighbor, then you can feel relatively secure using off-the-shelf encryption without worrying about too many details.

However, even if you are not a nation-state with an opponent that will invest unlimited resources to get your information, there are three main questions you should ask:

1. How long into the future would I like this information to remain secret? Based on this answer you can consult with an industry analyst as to projected computer power changes in the coming years. Any foreseeable breakthroughs in the math that could reduce the time needed to break the encryption. Then based on two factors, make the call: How paranoid do you feel you need to be according to your risk assessment, judged against the functionality you require and implementation costs?

2. Does my opponent have the resources to deal with this encryption? To break modern encryption on a PC could take longer than the life of the universe. Don't be confused by this statement: Consider what else your opponent might be willing to do to get your information. Encryption makes us feel safer, but it does not equate security.

As an alternative, also consider that encryption is a secret, and you might want to use several encryption schemes so as to not make one too secure to work with; you won't be able to trust people who run your daily operations to use it.

3. Because the algorithm is rarely the weakest link in real-world attacks, have I taken care of the implementation? Most attacks against encryption systems are against the implementation rather than the algorithm -- be it the programming, which should be done and reviewed by experts, or the procedures by which the encryption is put to use.

Further, side-channel attacks ranging from the less likely, such as TEMPEST (electromagnetic emanations) to Trojan horses (which are a significant threat), and from stolen laptops to buying off an employee, must not be left to chance. These should all be considered and planned for. The algorithm alone does not make you safe.

Follow Gadi Evron on Twitter: http://twitter.com/gadievron.

Gadi Evron is an independent security strategist based in Israel. Special to Dark Reading. Gadi is CEO and founder of Cymmetria, a cyber deception startup and chairman of the Israeli CERT. Previously, he was vice president of cybersecurity strategy for Kaspersky Lab and led PwC's Cyber Security Center of Excellence, located in Israel. He is widely recognized for ... View Full Bio

Comment  | 
Print  | 
More Insights
Newest First  |  Oldest First  |  Threaded View
Data Leak Week: Billions of Sensitive Files Exposed Online
Kelly Jackson Higgins, Executive Editor at Dark Reading,  12/10/2019
Lessons from the NSA: Know Your Assets
Robert Lemos, Contributing Writer,  12/12/2019
4 Tips to Run Fast in the Face of Digital Transformation
Shane Buckley, President & Chief Operating Officer, Gigamon,  12/9/2019
Register for Dark Reading Newsletters
White Papers
Current Issue
The Year in Security: 2019
This Tech Digest provides a wrap up and overview of the year's top cybersecurity news stories. It was a year of new twists on old threats, with fears of another WannaCry-type worm and of a possible botnet army of Wi-Fi routers. But 2019 also underscored the risk of firmware and trusted security tools harboring dangerous holes that cybercriminals and nation-state hackers could readily abuse. Read more.
Flash Poll
Rethinking Enterprise Data Defense
Rethinking Enterprise Data Defense
Frustrated with recurring intrusions and breaches, cybersecurity professionals are questioning some of the industrys conventional wisdom. Heres a look at what theyre thinking about.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
PUBLISHED: 2019-12-15
In the Linux kernel before 5.3.11, sound/core/timer.c has a use-after-free caused by erroneous code refactoring, aka CID-e7af6307a8a5. This is related to snd_timer_open and snd_timer_close_locked. The timeri variable was originally intended to be for a newly created timer instance, but was used for ...
PUBLISHED: 2019-12-15
python-requests-Kerberos through 0.5 does not handle mutual authentication
PUBLISHED: 2019-12-15
CFME (CloudForms Management Engine) 5: RHN account information is logged to top_output.log during registration
PUBLISHED: 2019-12-15
jersey: XXE via parameter entities not disabled by the jersey SAX parser
PUBLISHED: 2019-12-15
JBoss KeyCloak: Open redirect vulnerability via failure to validate the redirect URL.