How to Find Your TLS/SSL Certificate Private Key

A Step-by-Step Guide to Find the TLS/SSL Certificate Private Key

TLS and its earlier version SSL are encryption protocols that ensure communication, across a computer network by utilizing X509 certificates containing a key paired with a required private key, for operation.

When configuring TLS/SSL for a website or service you will require both the certificate file (containing the key ) and the private key file. If the private key is lost or inaccessible TLS/SSL connections won’t be successful.

This comprehensive guide will explain the various methods for locating a lost or forgotten private key for a TLS/SSL certificate on Windows, Linux, and Apache servers.

What is a Private Key for a TLS / SSL certificate?

An SSL/TLS certificate is made up of a key and a corresponding private key that work together mathematically to secure HTTPS connections by decrypting data encrypted with the public key.

Here are some important details about keys:

Losing the private key means you can no longer establish private, encrypted channels. Once you can find or recover the associated private key, the TLS/SSL certificate becomes unusable.

When Would You Need to Find a Private Key?

There are a few scenarios that may require locating a private key:

Finding the private key file quickly facilitates certificate renewals, migrations, disaster recovery, compliance, and troubleshooting. The next sections cover various methods of locating it.

Locating the Private Key File on Windows

Here are the steps to help find the private key file on Windows systems:

Check the Certificate Store

Search Known Storage Locations

Private keys on Windows are often stored as .PFX or .PVK files. Some common places to check include:

Use Windows search or PowerShell commands to find files with extensions like .pem, .key, .pfx, or the certificate thumbprint.

Check Any Backup Locations

Check backup directories or servers to see if a copy of the private key was saved:

Having an up-to-date backup means you can easily retrieve lost or damaged private keys.

Review Server Software Key Settings

For IIS, Apache, Nginx, and other server software, review the SSL certificate settings to determine if the key path or password may have been saved:

This can provide clues on where the key file originally resided.

Check Automation Tools or Scripts

For certificates managed through automation tools like PowerShell, Ansible, or Terraform – check scripts and output logs to see if the private key location or password was recorded.

Contact the Certificate Issuer

As a last resort, contact the certificate issuer to see if they still have the private key archived. This is unique, however, as the private key is meant to be kept private by the owner.

Locating the Private Key on Linux/Unix

Here are some methods for finding private key files on Linux, Unix, BSD, and other UNIX-like systems:

Look in Known Key Storage Directories

The openssl command line tool typically stores keys in /etc/ssl/private. Check there and /etc/ssl/certs for key files.

# Search these folders for private key file
sudo find /etc/ssl -name "*.key"

Other locations to check include:

Use the find command to search for .key, .pem or .crt files in likely locations.

Check OpenSSL Configuration

The openssl.cnf file may specify the storage location for private keys generated using OpenSSL:

# View the OpenSSL config
cat /etc/ssl/openssl.cnf | grep -i dir
# Look for the [ CA_default ] section
dir = /etc/pki/CA

This shows keys being stored in /etc/pki/CA – adapt the path as needed.

Look Through Web Server Configs

For Nginx, check ssl_certificate_key directives in the site configs:

# Look for private key locations 
grep -R "ssl_certificate_key" /etc/nginx/sites-enabled/

For Apache httpd, find SSLCertificateKeyFile entries:

# Search Apache config for private key file
grep -R "SSLCertificateKeyFile" /etc/httpd/conf.d/

This reveals where the server software expects to find the keys.

Review Automation Code or Scripts

Check any shell scripts, Ansible playbooks, CloudInit, or Terraform code used to automate certificate deployment. The private key path or password may be referenced.

Check Backup/DR Locations

Review backup directories and off-site disaster recovery locations in case the key was archived as part of a backup routine.

Having an offline backup of the private key is wise in case you need to restore it.

How to Find Private Keys for Apache TLS/SSL Certificates

Apache web server stores TLS certificates and keys in the SSLCertificateFile and SSLCertificateKeyFile directives in httpd-ssl.conf.

Here is how to find the private key when using Apache:

Check httpd-ssl.conf

Look in /etc/httpd/conf.d/httpd-ssl.conf for the SSLCertificateKeyFile setting:

SSLCertificateKeyFile /etc/pki/tls/private/localhost.key

This specifies the private key file path used when enabling SSL for the site or virtual host.

Search Key Storage Folders

Common Apache private key folders include:

Use find to search for .key files:

find /etc/pki/tls -name "*.key"

Look for Exported Keys

Apache allows exporting keys and certs to a .pfx file. Check for any .pfx files in and around the Apache folder.

Review Key Generation Scripts

The private key is generated when first creating a CSR using the openssl tool. Check any saved shell scripts that perform this OpenSSL CSR generation step – they may reference the key location.

Check Backup/DR Systems

See if the private key was archived or replicated to backup servers or disaster recovery systems.

How to Find Nginx Private Keys for SSL Certificates

Here are some tips for finding private key files for SSL certificates when using the Nginx web server:

Check Nginx Configuration Files

Look for ssl_certificate_key directives inside any server { } blocks:

server {
listen 443 ssl;
ssl_certificate_key /etc/ssl/private/nginx.key;
}

This shows the private key file path configured for that TLS/SSL certificate.

Search Typical Nginx Key Directories

Nginx usually stores keys in:

Use find to search:

sudo find /etc/ssl -name "*.key"

Review the nginx -T Output

The nginx -T command dumps all processed config values. Look for any ssl_certificate_key entries here.

Check opt/nginx if Installed from Packages

On systems like Ubuntu and Debian, where Nginx was installed from .deb packages, the default location is /opt/nginx/.

Examine the Nginx Docker Container

For Nginx running in Docker, exec into the container to search for key files:

docker exec -it nginx bash
find /etc/nginx

Inspect Automation Code or Scripts

Review any Terraform, Ansible, CloudInit, or shell scripts that deploy Nginx to see if the private key location is referenced.

Following these tips should help you track down the correct private key for your Nginx TLS/SSL certificates.

A Step-by-Step Guide to Recover Private Keys from Windows Certificate Backups

Windows Certificate Manager allows backing up certificates and private keys to .pfx or .p12 files. Here is how to restore the private key from these backup files:

certutil -dump backup.pfx

certutil -exportpfx -privatekey backup.pfx extracted.pvk

certutil -repairstore my extracted.pvk targetstore.pvk

How to Generate New Private Keys using OpenSSL Commands

If you have exhausted all options and need help finding the original private key, the only recourse is to generate a brand new private key.

Here is how to quickly generate a new private key:

OpenSSL

# Generate 2048 bit RSA private key
openssl genrsa -out new.key 2048
# Generate ECC key
openssl ecparam -genkey -name secp384r1 -out new.key

Windows OpenSSL

# Generate RSA key
openssl genrsa -out new.key 2048
# ECC key
openssl ecparam -genkey -name secp384r1 -out new.key

Final Thoughts

Locating the private key for your TLS/SSL certificate is a critical step in maintaining secure web communications. By following the steps outlined in this guide, you can efficiently retrieve the private key, whether it’s stored on your web server or in a certificate management platform.

Properly managing and safeguarding your private key is essential to preventing unauthorized access and ensuring the confidentiality of your encrypted data. With the right techniques, you can take control of your SSL/TLS security and keep your online presence secure.

Remember, the private key is the backbone of your SSL/TLS infrastructure – treat it with the utmost care.

Frequently Asked Questions

Here are some common questions about locating and managing TLS/SSL private keys:

Can I recover or reset a lost private key password?

No, private key passwords cannot realistically be recovered or reset without the original value. If the password is lost, you must generate a new private key. Always keep backups of all passwords.

My certificate was issued by an external CA – can I get the private key from them?

No, CAs keep only the public key and CSR. They do not retain copies of the certificate’s private keys, which remain with the subscriber.

Can I locate a private key if I only have the public key or certificate?

No, public certificates do not contain enough information to reconstruct the private key. You must find where the original private key file is stored.

If I lose the private key, do I have to re-issue all certificates?

Yes, losing a private key with no backup requires generating new key pairs and re-issuing all affected certificates. You cannot recreate private keys without the originals.

Can I tell if a found private key matches a certificate?

Yes, by generating the public key from the private key using openssl and matching it to the public key in the certificate. If they match, the private key is authentic.

What are the risks of exposed private keys?

Exposed private keys allow intercepting and decrypting confidential communications. They also enable eavesdropping, data theft, and compromise of the SSL/TLS channel. Therefore, private keys must always be closely guarded.

Priya Mervana

Verified Web Security Experts

Priya Mervana is working at SSLInsights.com as a web security expert with over 10 years of experience writing about encryption, SSL certificates, and online privacy. She aims to make complex security topics easily understandable for everyday internet users.