Almost 250,000 RSA keys were found to be broken as part of an investigation into a certificate vulnerability that could compromise internet of things (IoT) devices such as connected cars and medical implants.

Based on an analysis of approximately 175 million certificates, researchers at Keyfactor discovered that those sharing one of their prime factors with another could easily be compromised. When an IoT device attempted to connect to the internet, for example, a technique making use of the vulnerability could impersonate a server by re-deriving the key for an SSL/TLS server certificate.

Details about how the RSA keys were broken were initially released at the first IEEE Conference on Trust, Privacy and Security in Intelligent Systems and Applications.

How Certificate Security Can Suffer

An active public key is based on two large primes that are randomly chosen, but the research showed how often they share factors by using an algorithm that mined them for commonalities.

The results of the research, which builds upon similar investigations dating back to 2012, showed that one out of 172 certificates, or approximately 435,000, were weak. This could be due to a flaw in the random number generation that occurs when primes are chosen, according to the report.

If that happens, attackers who understand a computation known as the Greatest Common Devisor (GCD) could perform simple calculations to break the keys. This, in turn, could lead to data theft or devices malfunctioning since a device user wouldn’t be able to distinguish an attacker from someone with a legitimate certificate, the researchers added.

The dataset for the project was built by using proprietary tools designed to discover active RSA keys and millions of other samples gathered through certificate transparency logs.

Consider the Full Potential of Cryptography

Besides ensuring random number generation tools work properly, the researchers emphasized keeping IoT devices updated and securely installing firmware from the very beginning.

Security experts have also pointed out that the best cryptography goes beyond encryption, keys and certificates to look holistically at security. The goal should be to support not only confidentiality and privacy, for instance, but data integrity and non-repudiation. Cryptography services can help organizations meet those kinds of goals by delivering the right training and effective governance.