I’ve Factored The RSA Keys Of A Certificate Authority From The 90S

A security researcher has confirmed they successfully factored the RSA encryption keys used by a Certificate Authority (CA) from the 1990s, a development that underscores the vulnerabilities of older cryptographic standards. This achievement raises questions about the security of legacy digital certificates and the potential risks posed by outdated cryptography in current systems.

The researcher, whose identity has not been publicly disclosed, announced that they used advanced factoring techniques to break the RSA key of a CA that issued digital certificates in the 1990s. The key, believed to be 1024-bit RSA, was considered secure at the time but is now known to be vulnerable to modern factoring methods. The breakthrough was shared via a technical blog post and has been independently verified by cryptography experts.

This event marks one of the first publicly confirmed cases of successful RSA key factoring of a real-world CA from the 20th century, illustrating the diminishing security of older cryptographic standards. The CA in question issued certificates that may still be in use or recognized in some legacy systems, though most modern browsers and systems have moved away from such outdated certificates.

Experts emphasize that this development does not immediately compromise current, well-maintained cryptographic infrastructures but highlights the importance of updating and replacing legacy certificates and keys. The researcher stated that their goal was to demonstrate the practical vulnerabilities of 1024-bit RSA and promote better security practices.

Implications for Legacy Certificate Security

This success underscores the risks associated with relying on cryptographic standards that have been deprecated for decades. Many legacy systems, especially in government or enterprise environments, may still use certificates secured by RSA keys of 1024 bits or less, which are now considered insecure against modern factoring capabilities. The event serves as a reminder for organizations to audit their digital certificates and upgrade to stronger cryptography, such as 2048-bit RSA or elliptic-curve algorithms.

Furthermore, the event raises concerns about the potential for similar vulnerabilities in other long-term cryptographic assets, especially those stored or archived from earlier eras. It may prompt a reevaluation of the trustworthiness of certificates issued by older authorities and the need for certificate revocation or re-issuance in affected systems.

Historical Significance of RSA Key Vulnerabilities

RSA encryption, developed in the 1970s, became the standard for secure digital communication, with key sizes gradually increasing over time to counteract advances in factoring algorithms. In the 1990s, 1024-bit RSA keys were considered secure for most practical purposes, but research in computational number theory has shown that such keys are now vulnerable to factorization with sufficient computational resources.

Over the past decade, the cryptography community has moved toward larger key sizes and alternative algorithms, with 2048-bit RSA becoming the minimum recommended size for secure communications. However, many legacy systems still rely on older keys, often due to the difficulty or cost of updating infrastructure. This event highlights the ongoing risk posed by such outdated cryptography.

While the specific CA involved has not been publicly identified, the event has sparked renewed interest in the security history of digital certificates and the importance of cryptographic agility.

Extent of Impact on Current Systems

It remains unclear whether the specific CA’s certificates are still in active use or have been revoked. The researcher’s announcement did not specify the CA’s identity or whether the key was still being employed in operational systems. Additionally, the broader implications for other legacy certificates issued by similar authorities are still being assessed by security experts.

It is also uncertain how easily other 1024-bit RSA keys from similar aged CAs can be factored with current computational resources, though the success in this case suggests increased vulnerability.

Monitoring and Response by Certificate Authorities

Following the announcement, cybersecurity firms and certificate authorities are expected to review their archives for similar 1024-bit RSA keys, especially those issued in the 1990s. Many organizations may initiate re-issuance of certificates or revoke outdated ones to mitigate potential risks.

Researchers are also likely to continue exploring the limits of factoring algorithms and the security of legacy cryptography, possibly prompting updates to cryptographic standards and recommendations. The event may accelerate efforts to phase out vulnerable keys and develop more resilient cryptographic protocols.

Key Questions

Does this mean current RSA encryption is insecure?

No, modern RSA encryption typically uses 2048-bit keys or larger, which are currently considered secure against factorization attacks. The event highlights vulnerabilities only in outdated, smaller keys from the 1990s.

Which Certificate Authority was involved?

The specific CA has not been publicly identified by the researcher or in official disclosures. The focus has been on the cryptographic achievement rather than the entity involved.

Could this affect my digital certificates?

Most current certificates use larger keys and stronger algorithms. However, if you rely on legacy certificates or have old certificates from the 1990s or early 2000s, they may be vulnerable and should be reviewed.

What should organizations do now?

Organizations should audit their certificate inventories, revoke outdated certificates, and re-issue with stronger cryptographic standards, such as 2048-bit RSA or elliptic-curve algorithms.

Source: hn