Instagram Now Rotating TLS Certificates Daily with 1-Week Validity

Instagram has begun rotating its TLS certificates on a daily basis, with each certificate valid for just over a week.

This approach, which goes far beyond current industry standards, was discovered during routine network debugging and has since been confirmed through systematic monitoring and analysis.

Setup and Discovery

The anomaly was first noticed when a certificate for Instagram was found to have a validity period of only 53 days—unusual compared to the typical 90, 180, or 365-day certificates.

Further investigation revealed that, regardless of when checked, the certificate always had about eight days left before expiration.

This led to the hypothesis that Instagram was not only using short-lived certificates but also rotating them much more frequently than most major websites.

To test this, a dedicated script was set up to download and analyze Instagram’s certificates every five minutes.

Each certificate was hashed and stored, allowing for precise tracking of changes and validity periods over time. This method provided a clear window into Instagram’s certificate management practices.

Over the course of a month, the monitoring system collected data on 20 certificates per domain, with only minor interruptions due to machine reboots. The findings were striking:

• Daily Rotation: Instagram changes its TLS certificates every day, and occasionally even twice a day.
• Short Validity: Each new certificate is valid for just over eight days, and is replaced when it has a little more than seven days left before expiration.
• Separate Certificates: Both instagram.com and www.instagram.com use separate certificates, even though the main domain’s wildcard certificate could technically cover subdomains.
• Consistent Timing: Certificate swaps typically occur between 16:00 and 17:00 UTC, with a small window of variability likely due to network conditions.

Graphs of the certificate data showed a clear, daily increment in both the start and end times of certificate validity.

The process is highly automated and robust, with only minor anomalies attributable to external factors.

Instagram’s aggressive certificate rotation strategy is a significant departure from the industry norm, where certificates are typically valid for 90 days or more and rotated far less frequently.

This move may be aimed at minimizing the risk window for compromised keys, though it also raises questions about backend key management and operational complexity.

While the security benefits of such rapid rotation are still up for debate, Instagram’s approach is a clear signal of the direction in which web security practices may be heading as certificate lifetimes continue to shrink across the industry.

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