Splitting PEM Files A Comprehensive Guide To Separating Certificates And Keys

July 13, 2025 by StackCamp Team 78 views

How to Split a PEM File for Certificates and Keys

Introduction

When working with SSL/TLS certificates, you often encounter PEM files. PEM (Privacy Enhanced Mail) is a common format for storing cryptographic keys and certificates. A PEM file can contain one or more items, such as a private key, a certificate, or a certificate chain. Sometimes, you need to split a single PEM file into separate files for the certificate and the private key. This is particularly common when dealing with services or systems that require the certificate and key to be uploaded as separate files. For instance, when configuring Apple Push Notifications (APNs), you might use Fastlane to generate a PEM file that includes both the certificate and the key. However, the system you're uploading to might require these to be in two separate files. In this comprehensive guide, we'll explore how to split a PEM file effectively, ensuring you can manage your certificates and keys with ease.

Understanding PEM File Structure

Before diving into the splitting process, it’s crucial to understand the structure of a PEM file. A PEM file is a text file encoded in Base64, and it typically contains one or more blocks of data. Each block is enclosed between a BEGIN and an END marker. Common types of blocks you’ll find in a PEM file include:

-----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----: These markers enclose the certificate data.
-----BEGIN PRIVATE KEY----- and -----END PRIVATE KEY-----: These markers enclose the private key data.
-----BEGIN RSA PRIVATE KEY----- and -----END RSA PRIVATE KEY-----: Another common format for private keys.
-----BEGIN ENCRYPTED PRIVATE KEY----- and -----END ENCRYPTED PRIVATE KEY-----: Indicates an encrypted private key.

Knowing these markers is essential because they will guide you in splitting the PEM file correctly. The process involves identifying these blocks and extracting them into separate files.

Why Split a PEM File?

Splitting a PEM file is necessary in several scenarios. Here are a few common reasons:

System Requirements: Many systems and services require the certificate and private key to be uploaded as separate files. This is a common practice for security reasons, as it allows for more granular control over how these components are used.
Configuration: Certain applications or servers may require you to specify the paths to the certificate and key files separately in their configuration settings.
Security: Separating the certificate and key can enhance security. For example, you might store the private key in a more secure location than the certificate.
Compatibility: Some tools and libraries may not be able to handle a combined PEM file, necessitating the separation of certificate and key.

Understanding these reasons underscores the importance of knowing how to split a PEM file effectively.

Methods to Split a PEM File

There are several methods to split a PEM file, ranging from manual techniques using text editors to command-line tools. Here, we'll cover the most common and reliable methods.

1. Using a Text Editor (Manual Method)

The simplest way to split a PEM file is by using a text editor. This method is straightforward and doesn’t require any additional software, but it does require careful attention to detail to avoid errors. This manual method is particularly useful when you quickly need to extract the certificate or the key and don't have access to command-line tools. The key to successfully using a text editor is accurately identifying the BEGIN and END markers for each section.

Steps:

Open the PEM File: Open the PEM file using a text editor such as Notepad (on Windows), TextEdit (on macOS), or any other text editor.
Identify the Blocks: Look for the BEGIN and END markers for the certificate and private key. As mentioned earlier, these markers will look like -----BEGIN CERTIFICATE-----, -----END CERTIFICATE-----, -----BEGIN PRIVATE KEY-----, and -----END PRIVATE KEY-----. The certificate block typically starts with -----BEGIN CERTIFICATE----- and ends with -----END CERTIFICATE-----. The private key block usually starts with -----BEGIN PRIVATE KEY----- (or -----BEGIN RSA PRIVATE KEY-----) and ends with -----END PRIVATE KEY-----.
Copy the Certificate Block: Select the entire certificate block, including the BEGIN and END markers, and copy it to a new file. Save this file with a .pem or .crt extension (e.g., certificate.pem). Ensuring you include the markers is critical for the file to be correctly recognized as a certificate.
Copy the Private Key Block: Similarly, select the entire private key block, including the BEGIN and END markers, and copy it to another new file. Save this file with a .pem or .key extension (e.g., private.key). Just like with the certificate, including the markers is essential for the file to be valid.
Verify the Files: Open the newly created files to ensure they contain the correct blocks. The certificate file should contain only the certificate block, and the private key file should contain only the private key block. This verification step helps prevent issues later on when you try to use these files in your system or application.

Example:

If your original combined.pem file looks like this:

-----BEGIN CERTIFICATE-----
MII...
-----END CERTIFICATE-----
-----BEGIN PRIVATE KEY-----
NII...
-----END PRIVATE KEY-----

You would copy the content between -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- to certificate.pem, and the content between -----BEGIN PRIVATE KEY----- and -----END PRIVATE KEY----- to private.key.

2. Using Command-Line Tools (OpenSSL)

The most reliable and efficient way to split a PEM file is by using command-line tools, particularly OpenSSL. OpenSSL is a powerful cryptographic toolkit that includes a wide range of functions for managing SSL/TLS certificates and keys. It’s available on most Unix-like systems (including macOS and Linux) and can be installed on Windows as well. Using OpenSSL not only simplifies the splitting process but also ensures accuracy and avoids potential errors that can occur with manual methods. The OpenSSL approach is particularly beneficial when dealing with multiple files or when automation is required.

Prerequisites:

OpenSSL Installed: Ensure that OpenSSL is installed on your system. If it’s not, you can download and install it from the official OpenSSL website or use a package manager like apt (on Debian/Ubuntu), yum (on CentOS/RHEL), or brew (on macOS).

Steps:

The primary OpenSSL command we'll use is openssl crl2pkcs7, which can extract certificates from a PEM file. However, we'll also use openssl rsa and openssl x509 to handle private keys and certificates directly. Here’s how you can split the PEM file using OpenSSL:

Extract the Certificate: Use the openssl x509 command to extract the certificate from the PEM file. The command is as follows:
```
openssl x509 -in combined.pem -out certificate.pem -outform PEM
```
- -in combined.pem: Specifies the input file (the combined PEM file).
- -out certificate.pem: Specifies the output file for the certificate.
- -outform PEM: Specifies the output format as PEM.
This command reads the combined.pem file and extracts the certificate, saving it to certificate.pem. The -outform PEM option ensures that the output is in PEM format, which is crucial for compatibility with most systems.
Extract the Private Key: Use the openssl rsa command to extract the private key. If the key is encrypted, you’ll be prompted for the passphrase. The command is:
```
openssl rsa -in combined.pem -out private.key
```
If your private key is not in RSA format (e.g., it's an Elliptic Curve key), you might need to use openssl ec instead:
```
openssl ec -in combined.pem -out private.key
```
- -in combined.pem: Specifies the input file.
- -out private.key: Specifies the output file for the private key.
This command extracts the private key from combined.pem and saves it to private.key. If the private key is encrypted, OpenSSL will prompt you to enter the passphrase to decrypt the key before saving it to the output file.
Alternative Method for Private Key: If the above command doesn’t work, you can try using the openssl pkcs8 command, which is more versatile in handling different key formats:
```
openssl pkcs8 -in combined.pem -nocrypt -out private.key
```
If your key is encrypted, you'll need to remove the -nocrypt option and OpenSSL will prompt you for the passphrase:
```
openssl pkcs8 -in combined.pem -out private.key
```
This command attempts to extract the private key in PKCS#8 format, which is a standard format for storing private key information. The -nocrypt option tells OpenSSL that the key is not encrypted. If the key is encrypted, you should omit this option and enter the passphrase when prompted.
Verify the Files: You can verify the extracted certificate and private key using OpenSSL as well. To view the certificate details, use:
```
openssl x509 -in certificate.pem -text -noout
```
To view the private key details, use:
```
openssl rsa -in private.key -text -noout
```
These commands display the contents of the certificate and private key files in a human-readable format, allowing you to confirm that the extraction was successful and the files contain the expected information.

Example:

Suppose you have a combined.pem file. After running the OpenSSL commands:

openssl x509 -in combined.pem -out certificate.pem -outform PEM
openssl rsa -in combined.pem -out private.key

You will have two files: certificate.pem containing the certificate, and private.key containing the private key.

3. Using Scripting Languages (e.g., Python)

For more complex scenarios or when you need to automate the splitting process, using a scripting language like Python can be highly effective. Python provides powerful string manipulation and file handling capabilities, making it well-suited for parsing PEM files. This Python approach is particularly useful when you need to process multiple PEM files or integrate the splitting process into a larger workflow. The key to using Python effectively is understanding how to read the file, identify the certificate and key blocks, and write them to separate files.

Prerequisites:

Python Installed: Ensure that Python is installed on your system. Python is available on most operating systems and can be downloaded from the official Python website.

Steps:

Here’s a Python script that splits a PEM file into certificate and private key files:

#!/usr/bin/env python3

import os

def split_pem(input_file, certificate_output_file, private_key_output_file):
    """Splits a PEM file into certificate and private key files."""
    certificate_found = False
    private_key_found = False
    certificate_lines = []
    private_key_lines = []

    try:
        with open(input_file, 'r') as infile:
            lines = infile.readlines()

        with open(certificate_output_file, 'w') as certfile, open(private_key_output_file, 'w') as keyfile:
            for line in lines:
                if '-----BEGIN CERTIFICATE-----' in line:
                    certificate_found = True
                if certificate_found:
                    certificate_lines.append(line)
                if '-----END CERTIFICATE-----' in line:
                    certificate_found = False

                if '-----BEGIN PRIVATE KEY-----' in line or '-----BEGIN RSA PRIVATE KEY-----' in line:
                    private_key_found = True
                if private_key_found:
                    private_key_lines.append(line)
                if '-----END PRIVATE KEY-----' in line:
                    private_key_found = False

            certfile.writelines(certificate_lines)
            keyfile.writelines(private_key_lines)

        print(f"Certificate saved to {certificate_output_file}")
        print(f"Private key saved to {private_key_output_file}")

    except FileNotFoundError:
        print(f"Error: File not found: {input_file}")
    except Exception as e:
        print(f"An error occurred: {e}")

if __name__ == "__main__":
    input_pem_file = "combined.pem"  # Replace with your input PEM file
    output_certificate_file = "certificate.pem"
    output_private_key_file = "private.key"

    split_pem(input_pem_file, output_certificate_file, output_private_key_file)

Explanation:

Import os Module: This module is imported but not directly used in this script. It's included for potential future use, such as handling file paths.
split_pem Function: This function takes three arguments: the input PEM file, the output certificate file, and the output private key file. It reads the input file line by line and identifies the certificate and private key blocks based on the BEGIN and END markers.
File Handling: The function opens the input file for reading and the output files for writing. It uses try...except blocks to handle potential errors, such as the input file not being found or other exceptions that might occur during file processing.
Identifying Blocks: The script uses boolean flags (certificate_found and private_key_found) to track whether it is currently inside a certificate or private key block. It checks for the -----BEGIN CERTIFICATE-----, -----END CERTIFICATE-----, -----BEGIN PRIVATE KEY----- (or -----BEGIN RSA PRIVATE KEY-----), and -----END PRIVATE KEY----- markers in each line.
Extracting Lines: When a BEGIN marker is found, the corresponding found flag is set to True. All lines are then appended to the respective list (certificate_lines or private_key_lines) until the END marker is found, at which point the flag is set back to False.
Writing to Output Files: After processing all lines, the script writes the accumulated lines to the respective output files using the writelines method. This ensures that the entire certificate and private key blocks are written to the output files.
Error Handling: The script includes error handling for the case where the input file is not found and for any other exceptions that might occur during the process. This makes the script more robust and provides helpful error messages to the user.
Main Block: The if __name__ == "__main__": block is the entry point of the script. It defines the input and output file names and calls the split_pem function with these file names.
File Names: The script defines default file names for the input PEM file (combined.pem) and the output certificate (certificate.pem) and private key (private.key) files. These can be easily modified to suit different use cases.

How to Use:

Save the Script: Save the above code to a file, for example, split_pem.py.
Run the Script: Open a terminal or command prompt, navigate to the directory where you saved the script, and run it using python3 split_pem.py. Make sure you have the combined.pem file in the same directory, or modify the script to specify the correct path.
```
python3 split_pem.py
```
The script will output the paths to the created certificate and private key files.

Example:

If you run the script with a combined.pem file, it will create certificate.pem and private.key files in the same directory.

4. Using Online Tools

While not recommended for sensitive keys due to security concerns, several online tools can split PEM files. These tools are convenient for quick, one-off tasks, but you should exercise caution when using them, especially with private keys. Always ensure that the tool is reputable and uses secure data handling practices. The key consideration when using online tools is the security of your data. If you're handling sensitive private keys, it's generally best to avoid online tools and use offline methods like OpenSSL or scripting languages.

Steps:

Search for an Online PEM Splitter: Use a search engine to find an online PEM splitter tool. Look for tools with good reviews and a clear privacy policy.
Upload the PEM File: Follow the tool's instructions to upload your PEM file. Be cautious about the file size limits and the tool's security measures.
Split the File: The tool should automatically split the PEM file into certificate and private key components.
Download the Files: Download the split files to your computer. Ensure that the downloaded files are stored securely.

Considerations:

Security Risks: Uploading private keys to online tools poses a significant security risk. If the tool is compromised or malicious, your private key could be exposed.
Privacy Policies: Review the privacy policy of the online tool to understand how your data is handled.
Reputation: Use reputable tools with positive reviews and a track record of security.

Recommendation:

For sensitive data, it is highly recommended to use offline methods like OpenSSL or scripting languages instead of online tools.

Best Practices for Handling PEM Files

Handling PEM files correctly is crucial for maintaining the security of your systems and applications. Here are some best practices to follow:

1. Secure Storage of Private Keys

Private keys are the most sensitive part of your SSL/TLS setup. They should be stored securely and protected from unauthorized access. Secure storage of private keys is paramount to maintaining the integrity and confidentiality of your encrypted communications. A compromised private key can lead to severe security breaches, including data decryption, impersonation, and other malicious activities. Therefore, it is essential to implement robust security measures to safeguard your private keys.

Key Considerations:

Encryption at Rest: Encrypt your private keys at rest. This means that the key should be stored in an encrypted format, adding an extra layer of protection. You can use various encryption methods, such as AES (Advanced Encryption Standard), to encrypt the key file. The passphrase or key used to encrypt the private key should be stored separately and securely.
Access Control: Implement strict access control measures to limit who can access the private keys. Only authorized personnel or systems should have access. Use file system permissions and access control lists (ACLs) to restrict access to the key files. Regularly review and update these access controls to ensure they remain effective.
Hardware Security Modules (HSMs): For high-security environments, consider using HSMs. These are dedicated hardware devices designed to securely store and manage cryptographic keys. HSMs provide a tamper-resistant environment and are often used in critical infrastructure and financial systems.
Key Rotation: Regularly rotate your private keys. Key rotation involves generating a new key pair and revoking the old key. This reduces the risk associated with key compromise. The frequency of key rotation depends on your security requirements and the sensitivity of the data being protected.
Secure Backups: Back up your private keys securely. Backups should also be encrypted and stored in a separate, secure location. Regularly test your backup and recovery procedures to ensure they work correctly.
Avoid Storing in Code Repositories: Never store private keys in code repositories, such as Git. Code repositories are often shared among developers, and storing keys in these repositories can expose them to unauthorized access. Use environment variables or configuration files to manage key paths or references.
Monitor Access: Monitor access to your private keys. Implement logging and auditing mechanisms to track who is accessing the keys and when. This helps in detecting and responding to unauthorized access attempts.

By following these practices, you can significantly enhance the security of your private keys and protect your systems from potential threats.

2. Proper File Permissions

Set appropriate file permissions for your PEM files, especially the private key file. On Unix-like systems, a common practice is to set the permissions to 600 (read and write only for the owner) for the private key file. Proper file permissions are crucial for safeguarding your private keys and certificates from unauthorized access. Incorrectly configured permissions can leave your sensitive cryptographic materials vulnerable to compromise. Therefore, it is essential to understand and implement appropriate file permissions to protect your PEM files.

Setting File Permissions on Unix-like Systems:

On Unix-like operating systems, such as Linux and macOS, file permissions are managed using a three-digit octal number. Each digit represents the permissions for the owner, group, and others, respectively. The digits are calculated by adding the following values:

4: Read permission
2: Write permission
1: Execute permission

For example, a permission of 600 means:

Owner: Read (4) + Write (2) = 6
Group: No permissions (0)
Others: No permissions (0)

This configuration ensures that only the owner of the file can read and write it, while no one else has any access.

Steps to Set File Permissions:

Identify the Private Key File: Locate the private key file on your system. This file typically has a .key or .pem extension and contains the private key data.
Open a Terminal: Open a terminal or command prompt on your Unix-like system.
Use the chmod Command: Use the chmod (change mode) command to set the file permissions. The command syntax is:
```
chmod 600 private.key
```
Replace private.key with the actual name of your private key file.
Verify the Permissions: You can verify the file permissions using the ls -l command:
```
ls -l private.key
```
The output will show the file permissions in the first column. For example:
```
-rw------- 1 user group 1704 Jul 1 10:00 private.key
```
The -rw------- indicates that the owner has read and write permissions, while the group and others have no permissions.

Best Practices for File Permissions:

Private Key Files: Set the permissions for private key files to 600 to ensure that only the owner can read and write the file. This is the most common and recommended practice for private key security.
Certificate Files: Certificate files (with .crt or .pem extensions) can have more relaxed permissions since they do not contain sensitive information. A common permission setting for certificate files is 644, which allows the owner to read and write, and the group and others to read.
Avoid World-Readable Permissions: Never set permissions that make your private key files world-readable (e.g., 644 or 777). This can expose your keys to unauthorized access.
Regularly Review Permissions: Regularly review the file permissions on your system, especially for sensitive files like private keys. Use tools like ls -l to check the permissions and ensure they are correctly configured.

By implementing proper file permissions, you can significantly reduce the risk of unauthorized access to your private keys and certificates, enhancing the overall security of your systems.

3. Keep Keys and Certificates Separate

Store your private keys and certificates in separate directories. This helps in managing them more effectively and reduces the risk of accidental exposure. Keeping keys and certificates separate is a fundamental security practice that enhances the organization and protection of your cryptographic materials. By segregating private keys and certificates into distinct directories, you minimize the risk of accidental exposure and simplify access control management. This separation ensures that sensitive keys are stored in a more secure environment, while certificates, which are less sensitive, can be managed with different access policies. This method is a cornerstone of robust security practices.

Benefits of Separating Keys and Certificates:

Enhanced Security: Storing private keys in a separate directory allows you to apply stricter access controls. You can limit access to the key directory to only authorized personnel or systems, reducing the risk of unauthorized access.
Reduced Accidental Exposure: Separating keys from certificates reduces the likelihood of accidentally exposing private keys. For example, if you are backing up or sharing certificate files, you can exclude the key directory, ensuring that the private keys are not inadvertently included.
Simplified Management: Separate directories make it easier to manage keys and certificates. You can apply different policies and procedures to each directory, such as backup schedules, access controls, and monitoring.
Improved Organization: Keeping keys and certificates separate improves the overall organization of your cryptographic materials. This makes it easier to locate specific files and reduces the risk of confusion or errors.
Compliance: Many security standards and compliance frameworks recommend or require the separation of keys and certificates as a best practice.

Steps to Separate Keys and Certificates:

Create Directories: Create two separate directories: one for private keys and one for certificates. Choose descriptive names for these directories, such as private_keys and certificates.
```
mkdir private_keys
mkdir certificates
```
Move Files: Move your private key files (typically with .key or .pem extensions) to the private_keys directory and your certificate files (typically with .crt or .pem extensions) to the certificates directory.
```
mv private.key private_keys/
mv certificate.pem certificates/
```
Set Permissions: Set appropriate file permissions for the key and certificate directories. For the private_keys directory, ensure that only authorized users have access. For example, you can set the permissions to 700 for the directory itself and 600 for the key files within it.
```
chmod 700 private_keys
chmod 600 private_keys/*
```
For the certificates directory, you can set more relaxed permissions, such as 755 for the directory and 644 for the certificate files.
```
chmod 755 certificates
chmod 644 certificates/*
```
Update Configurations: Update any configurations or scripts that reference the key and certificate files to reflect the new directory structure. This ensures that your systems and applications can still access the files correctly.
Regularly Review: Regularly review the directory structure and file permissions to ensure that the separation of keys and certificates is maintained and that access controls are properly enforced.

By separating your private keys and certificates into distinct directories, you enhance the security and manageability of your cryptographic materials, reducing the risk of accidental exposure and simplifying access control.

4. Use Strong Passphrases for Encrypted Keys

If your private key is encrypted, use a strong passphrase. A strong passphrase should be long, complex, and unique. Using strong passphrases for encrypted keys is a critical security measure that protects your private keys from unauthorized access. Encryption adds a layer of security to your private keys, ensuring that they cannot be used without the correct passphrase. However, the strength of this protection depends heavily on the quality of the passphrase. A weak passphrase can be easily cracked, rendering the encryption ineffective. Therefore, it is essential to use strong, complex passphrases to safeguard your encrypted keys.

Characteristics of a Strong Passphrase:

Length: A strong passphrase should be at least 12 characters long, and ideally longer. Longer passphrases are exponentially more difficult to crack.
Complexity: The passphrase should include a mix of uppercase letters, lowercase letters, numbers, and symbols. This increases the complexity and makes it harder to guess or crack using brute-force methods.
Uniqueness: The passphrase should be unique and not reused across different accounts or systems. Reusing passphrases increases the risk that a compromise of one passphrase could expose multiple accounts or systems.
Randomness: The passphrase should be generated randomly and not based on personal information, dictionary words, or common patterns. Avoid using names, dates, or other easily guessable information.
Memorability (Optional): While randomness is important, the passphrase should also be memorable enough that you can recall it without writing it down. However, memorability should not come at the expense of complexity and randomness. Consider using a passphrase manager to securely store and manage complex passphrases.

Best Practices for Passphrase Management:

Use a Passphrase Generator: Use a passphrase generator to create strong, random passphrases. Many online tools and password managers can generate passphrases that meet the criteria for strength and complexity.
Avoid Dictionary Words: Do not use dictionary words or phrases in your passphrases. These are easily cracked using dictionary attacks.
Mix Characters: Include a mix of uppercase letters, lowercase letters, numbers, and symbols in your passphrases. This significantly increases the complexity.
Regularly Update Passphrases: Regularly update your passphrases, especially for sensitive keys. The frequency of updates depends on your security requirements and the sensitivity of the data being protected.
Securely Store Passphrases: Store your passphrases securely. Use a password manager or other secure method to store and manage your passphrases. Avoid writing them down on paper or storing them in plain text files.
Consider Multi-Factor Authentication (MFA): For highly sensitive keys, consider using multi-factor authentication (MFA) to add an extra layer of security. MFA requires multiple forms of authentication, such as a passphrase and a one-time code from a mobile app.

Example of Generating a Strong Passphrase:

openssl rand -base64 32

This OpenSSL command generates a 32-byte random string encoded in Base64, which can be used as a strong passphrase.

By using strong passphrases for your encrypted keys and following best practices for passphrase management, you can significantly enhance the security of your cryptographic materials and protect them from unauthorized access.

5. Regularly Review and Rotate Keys and Certificates

Regularly review your keys and certificates and rotate them as needed. Key rotation involves generating new keys and certificates and revoking the old ones. This reduces the risk associated with key compromise. Regularly reviewing and rotating keys and certificates is a critical security practice that minimizes the risk associated with compromised cryptographic materials. Key rotation involves generating new keys and certificates and revoking the old ones, ensuring that even if a key is compromised, the potential damage is limited. This proactive approach to security helps maintain the integrity and confidentiality of your systems and applications. The key to effective key rotation is establishing a schedule and following it consistently.

Benefits of Key and Certificate Rotation:

Reduced Risk of Key Compromise: Key rotation limits the time window during which a compromised key can be used. If a key is compromised, the attacker can only use it until the next rotation.
Compliance with Security Policies: Many security standards and compliance frameworks require regular key rotation as a best practice. Rotating keys helps you meet these requirements and maintain a strong security posture.
Protection Against Brute-Force Attacks: Regularly rotating keys reduces the effectiveness of brute-force attacks. Even if an attacker is attempting to crack a key, the key will be rotated before they have a chance to succeed.
Improved Trust: Regular key rotation can improve trust with your users and partners. It demonstrates a commitment to security and helps maintain confidence in your systems and applications.
Adaptation to Changing Security Needs: Key rotation allows you to adapt to changing security needs and emerging threats. You can use stronger cryptographic algorithms or longer key lengths as needed.

Steps for Key and Certificate Rotation:

Establish a Rotation Schedule: Determine the frequency at which you will rotate your keys and certificates. The rotation schedule should be based on your security requirements and the sensitivity of the data being protected. Common rotation intervals range from 90 days to one year.
Generate New Keys and Certificates: Generate a new key pair and certificate using a trusted certificate authority (CA) or your own internal CA. Ensure that the new keys and certificates meet your security requirements, such as key length and cryptographic algorithm.
Deploy New Certificates: Deploy the new certificates to your systems and applications. This may involve updating configuration files, installing new certificates on servers, and distributing new certificates to clients.
Revoke Old Certificates: Revoke the old certificates with your CA. This prevents them from being used to establish secure connections. Revocation involves submitting a certificate revocation request to the CA and publishing the revoked certificate in a certificate revocation list (CRL).
Update Key Storage: Update your key storage systems to reflect the new keys and certificates. This may involve encrypting the new keys, setting appropriate file permissions, and storing the keys in a secure location.
Test the New Configuration: Test the new configuration to ensure that it is working correctly. Verify that secure connections can be established using the new certificates and that the old certificates are no longer accepted.
Document the Process: Document the key rotation process, including the steps taken, the dates of rotation, and the reasons for rotation. This helps ensure that the process is followed consistently and that any issues are tracked and resolved.

Best Practices for Key and Certificate Rotation:

Automate the Process: Automate the key rotation process as much as possible. This reduces the risk of human error and ensures that keys are rotated on schedule.
Use a Certificate Management System: Use a certificate management system to manage your keys and certificates. These systems provide tools for generating, deploying, and revoking certificates.
Monitor Certificate Expiry: Monitor the expiry dates of your certificates and plan for rotation well in advance. This helps prevent unexpected outages due to expired certificates.
Communicate Changes: Communicate key and certificate changes to your users and partners. This helps ensure that they are aware of the changes and can take any necessary steps on their end.

By regularly reviewing and rotating your keys and certificates, you can significantly reduce the risk of key compromise and maintain a strong security posture.

Conclusion

Splitting a PEM file into separate certificate and private key files is a common task in SSL/TLS certificate management. Whether you choose to use a text editor, OpenSSL, a scripting language like Python, or, with caution, an online tool, understanding the process and best practices is crucial. Remember to prioritize the security of your private keys by storing them securely, setting proper file permissions, and using strong passphrases. By following the guidelines outlined in this article, you can effectively manage your PEM files and ensure the security of your systems and applications. The key takeaway is that careful handling of your PEM files, especially private keys, is paramount for maintaining a secure environment.