A Basic Overview of an SSL Certificate
Secure Sockets Layer (SSL) and Transport Layer Security (TLS) certificates are an essential part of internet security. SSL/TLS Certificates Work by allowing encrypted connections between a web server and a browser, ensuring all data passed between the server and browser remains private. This beginner’s guide will explain what SSL is, how SSL/TLS certificate works to secure connections, the different types of certificates available, and how to get an SSL/TLS certificate for your own website. With websites becoming increasingly targeted by hackers, utilizing SSL/TLS certificates has become a necessity for protecting user data.
By learning the basics of how SSL/TLS Certificates Work, you can better secure your own online presence and data.
Key Takeaways
- SSL/TLS certificates allow secure, encrypted connections between a web server and a browser.
- Certificates verify the identity of a website and enable data encryption through HTTPS.
- Certificates contain information about the website and the CA that issued it.
- Browsers and devices maintain trusted root CA certificates that validate SSL certificates.
- The certificate issuance process involves generating a CSR and validating the requester’s identity.
- CAs can issue domain-validated, organization-validated, and extended validation certificates.
- SSL/TLS involves an initial handshake to establish an encrypted session and exchange keys.
- Encryption and decryption between server and browser protects data in transit.
- Up-to-date encryption protocols and ciphers should be used to ensure optimal security.
How SSL/TLS Works?
SSL/TLS certificates enable trusted encrypted communication between a web server (website) and a client (browser). Here is an overview of how the technology works:
- A Certificate Authority issues an SSL certificate to a person, organization, or website after validating identity.
- The certificate contains identifying information and the website’s public key.
- The website installs the certificate on its web server.
- Browsers and devices maintain a store of trusted root CA certificates pre-installed by the vendor.
- To access a website over HTTPS, the browser initiates a handshake process with the web server.
- The server presents its SSL certificate and public key to the browser.
- The browser verifies the certificate signature against its trusted root store.
- If valid, the browser generates a symmetric session key and encrypts it with the server’s public key.
- The encrypted session key is sent to the server, allowing both parties to derive the symmetric key for encrypting and decrypting data.
- An encrypted HTTPS session is established, allowing private communication.
- Data transmitted between the server and browser remains confidential through encryption.
SSL/TLS Certificate Issuance Process Steps
For a CA to issue an SSL certificate to a website, the owner must provide proof of identity and submit a Certificate Signing Request (CSR). Here are the steps involved:
- Generate Private Key: The website owner first generates a private and public key pair on the server that will use the certificate. The private key must be kept safe.
- Create CSR: A Certificate Signing Request (CSR) is an encoded file that contains the public key and information about the website requesting it, such as its domain name, organization details, location, and more.
- Submit Identity Proof: The CA will validate that the request comes from the legitimate owner of the domain in one of three ways, depending on the certificate type:
- Domain Validation: Proves control of the domain via email, DNS records, etc.
- Organization Validation: Verifies legal entity status and identity of the organization.
- Extended Validation: The highest level of verification for organizations and legal identities.
- CA Issues SSL Certificate: Upon approval, the CA will issue an SSL certificate containing the domain/company details and public key. The cert is digitally signed with the CA’s private key.
- Install Certificate on Server: The owner installs the newly issued SSL certificate on the web server housing the website. The private key is also installed and kept secret.
How Browsers Validate Certificates
For browsers to trust the identity declared in the SSL certificate during a handshake, the certificate must be validated against the browser’s trusted root store:
- Browsers and devices come pre-installed with root certificates from major Certificate Authorities, such as Comodo, Symantec, GoDaddy, GlobalSign, DigiCert, and more.
- The browser has a built-in list of trusted CA root certificates that verify whether any certificate issued to a website came from a trusted source.
- When a browser connects to a server over HTTPS, the server provides its SSL certificate containing signature information.
- The browser validates the cert’s signature against its root store to confirm a trusted CA signed it. This proves the certificate is authentic.
- The browser then checks that the domain name requested matches the information on the certificate, ensuring you are communicating with the correct server.
- If both signature validation and domain name check out, the SSL certificate can be trusted. The browser will display a padlock icon to indicate the site is secure.
- Any certificate error will generate a warning prohibiting access to the HTTPS site until the problem is corrected.
Vendors regularly update the root stores in browsers and devices to provide an updated list of trusted CAs that can validly sign certificates. This is a key component of the SSL/TLS ecosystem.
SSL/TLS Handshake Process
When a browser attempts to connect to a web server over HTTPS, a handshake process initiates to establish an encrypted session:
- Connection: The browser connects to the server requesting access via HTTPS rather than HTTP.
- Verification: The server presents its SSL certificate containing public key and identity information like organization and domain name.
The browser checks whether the certificate is trusted by validating the signature against root certificates and ensuring that the domain name matches.
- Key Exchange: If the certificate is valid, the browser generates a symmetric session key for encrypting data.
The public key from the server’s certificate is used to encrypt the symmetric session key and securely send it to the server.
- Encryption Enabled: Using the symmetric session key, both parties can symmetrically encrypt and decrypt all data transmitted across the session.
An encrypted HTTPS connection is established, allowing private communication.
This handshake enables both parties to:
- Verify the identity of the server
- Exchange encryption keys securely
- Encrypt the connection to protect data in transit
Once the handshake is complete, all traffic flowing between the browser and server will be encrypted by default, including any cookies, data submissions, or page content. The padlock icon indicates the secure HTTPS connection status.
SSL/TLS Encryption & Keys
The encryption mechanisms used by SSL/TLS provide data security and integrity to HTTPS transactions:
- Symmetric Encryption: This uses a shared secret key by both parties to encrypt and decrypt information. Fast performance. Used to encrypt bulk data sent across the session.
- Asymmetric Encryption: Uses matched public-private key pairs where one key encrypts and the other decrypts. Key exchange is done publicly. Used initially to share symmetric keys.
- Hash Functions: Cryptographic hashing of messages to produce digest used to detect tampering. Used for things like digital signatures.
- Encryption Ciphers: Encryption cipher suites that define algorithms used for key exchange, symmetric encryption, and hashing functions. The cipher strength must match that of the server and browser.
- Key Length: Longer public and private key length increases strength against attacks. At least 2048-bit is recommended for RSA keys.
SSL/TLS provides a robust mechanism for securing interactions and sensitive data transfers by leveraging secure encryption protocols and best practices.
Final Thoughts
In conclusion, SSL/TLS certificates are a vital component of secure online communication, enabling the encrypted exchange of data between a web server and a client.
By verifying the identity of the server and establishing a secure connection, these digital certificates help protect sensitive information such as login credentials, financial data, and personal details from interception by malicious actors.
The process of obtaining, managing, and properly configuring SSL/TLS certificates can be complex, but is essential for safeguarding the confidentiality and integrity of digital transactions.
As the reliance on internet-based services continues to grow, the importance of SSL/TLS certificates will only increase, underscoring the need for a thorough understanding of how they function to ensure a secure online environment.
Frequently Asked Questions (FAQs)
What is the difference between SSL and TLS?
SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are technical precursors and successors. TLS 1.0 was based on SSL 3.0. TLS is the latest protocol version supporting current encryption methods. SSL is still used as the umbrella term, but TLS is the standard.
Do all websites need an SSL certificate?
SSL certificates are crucial for any website that transmits private user data like logins, personal info, financial information, or other sensitive details. All ecommerce sites should use HTTPS. SSL also increasingly impacts search engine rankings. While some sites, like basic blogs, may not need encryption, SSL is recommended for nearly everyone.
How much do SSL certificates cost?
SSL pricing depends on the validation type and features, but extended validation certificates typically cost $150-USD 400 annually. Domain and organization-validated certificates can cost as little as $10-$50 per year. Volume discounts are available from most CAs. Free certificates do exist but may have drawbacks.
How long does it take to get an SSL certificate?
The issuance timeline depends on the validation process required. Domain-validated certificates can be issued within minutes or hours. Organization and extended validation certificates that require company vetting can take 1-5 days for approval. Automated certificate issuance and installation make SSL certificates easy to get.
Can I use an SSL certificate on multiple domains?
You can secure multiple domains and subdomains with a SAN certificate. Wildcard certificates also secure unlimited subdomains on one base domain. Alternatively, some CAs may allow one SSL certificate to be installed on up to 5 domains. However, a single domain certificate only protects one FQDN.
What are the different SSL errors?
Common SSL errors include certificate domain mismatch, expired certificate, not yet valid, untrusted/invalid issuer, incorrect algorithm, self-signed certificate, revoked certificate, etc. Errors will cause the browser to display warnings and block access to the HTTPS site until the underlying issue is resolved.
What does enabling HTTPS and SSL do?
Enabling HTTPS SSL/TLS encryption on a website involves purchasing and installing an SSL certificate on your server and redirecting site pages from HTTP to HTTPS. This provides a trusted identity, activates encryption for all traffic, gives browsers visual trust indicators, and enables compliance with regulations related to the transmission of sensitive data.
Why use a certificate authority instead of a self-signed certificate?
Self-signed certificates are not issued or validated by a trusted third-party CA. Browsers cannot verify their authenticity, so they will display warnings or block users. CA-signed certificates are trusted by all major browsers and devices by default, avoiding errors and building user trust through validation.
Can I use one SSL certificate for multiple websites?
Technically, it is possible to use one SSL certificate across multiple websites or domains. However, this should only be done for a small number of internal domains behind a load balancer or reverse proxy server. Due to potential issues, public websites must use separate SSL certificates for each unique site.
Jinu Arjun
