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A cryptographic time capsule and its modern implications

Factoring RSA Keys of a Certificate Authority from the 90s

Security Research

02

The Challenge

Understanding the cryptographic landscape of the 1990s

What Are RSA Keys and Certificate Authorities?

  • 01
    RSA Encryption A foundational public-key cryptosystem that enables secure communication through mathematical complexity
  • 02
    Certificate Authorities (CAs) Trusted entities that issue digital certificates, vouching for the identity of websites and services
  • 03
    The 90s Crypto Landscape Early cryptographic implementations often used shorter key lengths, creating vulnerabilities exploitable today
  • 04
    The Discovery A researcher successfully factored RSA keys from a defunct CA, revealing critical security lessons
512-bit
Key length used by the 90s Certificate Authority
Modern standards require 2048-bit or 4096-bit keys for equivalent security
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The Breakthrough

How the RSA keys were factored

The Factoring Process

1

Discovery

Identified archived certificates from the defunct CA

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2

Extraction

Recovered public keys from certificate data

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3

Computation

Applied modern factoring algorithms to the 512-bit keys

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4

Success

Derived the private keys, breaking the encryption

Key Takeaways

schedule

Cryptographic Aging

Encryption standards have expiration dates; what was secure yesterday may not be secure today

security

Legacy Risks

Older systems and archived certificates can remain active in unexpected places

key

Key Length Matters

The dramatic gap between 512-bit and modern 2048+ bit keys underscores the need for regular updates

visibility

Research Value

Historical cryptographic analysis reveals valuable lessons for modern security practices

Thank You

Exploring the past to secure the future

https://mcpherrin.ca/2026/09/07/rsa.html
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