Private And Public Keys - SSL.com (2024)

• SSL Support Team
• June 12, 2023
• Certificate Type, S/MIME, Client, and Document Signing, SSL/TLS
• SSL and Digital Certificates, SSL/TLS

The SSL/TLS protocol uses a pair of keys – one private, one public – to authenticate, secure and manage secure connections. These keys are a linked pair of text files and are created together as a pair when you create your Certificate Signing Request (CSR).

SSL works by making one key of the pair (the public key) known to the outside world, while the other (the private key) remains a secret only you know.

What is the Private Key?

Private keys play a fundamental role in digital certificates, serving as the cornerstone of secure online communication. Understanding the importance of private keys is crucial for businesses and individuals aiming to safeguard their sensitive information and maintain a secure online environment.

The private key is used to digitally sign your Certificate Signing Request (CSR), and later to secure and verify connections to your server.

Your private key should be closely guarded, since anyone with access to it can readily break your encryption. (Note again that the private key is just a text file – however, it’s a really important text file and should be protected accordingly.)

If you lose your private key, or believe it was compromised in any way, SSL.com recommends “re-keying” your certificate. To rekey, you’ll create and submit a new CSR, and SSL.com will reissue your certificate using your new key pair. SSL.com offers this as a free service for the lifetime of your certificate – for more information, see this article on how to handle a lost or compromised private key.

What are Important Features of the Private Key?

1. Security through Asymmetric Encryption: Private keys are an integral part of asymmetric encryption systems, such as the widely used RSA algorithm. By leveraging private and public key pairs, these systems enable secure communication, data integrity, and authentication. The private key, known only to the certificate owner, allows for the creation of digital signatures that can be verified using the corresponding public key.

2. Authentication and Trust: Digital certificates serve as electronic credentials that validate the identity of individuals, organizations, or websites. Private keys are used to generate digital signatures, which verify the authenticity and integrity of data transmitted over the internet. By safeguarding the private key, certificate owners ensure that only trusted entities can generate valid digital signatures, establishing trust in online interactions.

3. Encryption and Confidentiality: In SSL/TLS certificates, private keys are employed to initiate secure connections and encrypt sensitive data. Websites that utilize SSL/TLS encryption provide a secure environment for transmitting confidential information, such as login credentials, financial details, or personal data. The private key’s secrecy ensures that only authorized entities possess the means to decrypt the encrypted data, safeguarding it from unauthorized access.

4. Prevention of Fraudulent Activities: A compromised private key can lead to severe security breaches, enabling attackers to impersonate the certificate owner or intercept and manipulate encrypted communications. With unauthorized access to the private key, cybercriminals can create fraudulent digital signatures, compromise the authenticity of digital certificates, and deceive users. Protecting the private key is crucial in mitigating the risk of fraudulent activities and maintaining the integrity of online transactions.

5. Compliance and Regulatory Requirements: Various industries, such as finance, healthcare, and e-commerce, are subject to strict security regulations and compliance standards. Private key protection is often a requirement for meeting these guidelines. By implementing robust security measures to safeguard private keys, organizations can ensure compliance with industry-specific regulations and maintain the trust of their customers.

The private key of a digital certificate plays a vital role in ensuring online security, confidentiality, and trust. By understanding the importance of private keys and implementing robust security measures to protect them, businesses and individuals can safeguard sensitive information, establish trust in online interactions, and mitigate the risk of cyber threats. Maintaining the secrecy and integrity of private keys is essential in creating a secure online environment where users can confidently share data and engage in secure transactions.

What is the Public Key?

The public key, by contrast, is distributed as widely as possible – it’s included as part of your SSL certificate, and works together with your private key to make sure that your data is encrypted, verified and not tampered with during transport.

Anyone with access to your public key can verify that your message is authentic without having to know your secret private key.

What are Important Features of the Public Key?

1. Public keys are a vital component of asymmetric encryption systems like RSA. They enable secure communication by allowing users to encrypt data that can only be decrypted with the corresponding private key. By utilizing public keys, digital certificates facilitate secure communication channels, protecting sensitive data from unauthorized access.
2. Public keys enable the verification of digital signatures created with the corresponding private keys. These digital signatures establish data integrity and authentication, assuring the recipient that the transmitted information originates from a trusted source and remains unaltered during transit. Digital certificates employ public keys to validate the authenticity of the certificate holder, providing users with confidence in the legitimacy of their online interactions.
3. Public keys serve as a cornerstone in establishing trust between parties involved in online transactions. By incorporating public keys in digital certificates, organizations can demonstrate their identity and legitimacy, instilling confidence in customers and partners. Public key infrastructure (PKI) leverages the power of public keys to create a trusted framework for secure online interactions, paving the way for e-commerce, online banking, and other critical online services.
4. Public keys provide a scalable and interoperable solution for secure communication. They can be easily shared and distributed among multiple entities without compromising security. Public key encryption algorithms are widely supported and standardized, ensuring compatibility across different platforms, devices, and applications. This flexibility and interoperability make public keys an essential element in creating a secure and universally accessible online environment.