September 2023

In today’s digital landscape, a valid SSL certificate signed by a trusted Certificate Authority (CA) is an absolute necessity for websites. If your SSL certificate expires or gets revoked, web browsers will no longer trust your site, potentially causing security concerns. To determine the validity of your SSL certificate, browsers employ the Online Certificate Status Protocol (OCSP). However, OCSP, in its original form, comes with some limitations, which is where OCSP stapling comes into play, successfully addressing these issues. In this article, we will delve into what OCSP stapling is, how it works, and why it is a crucial component of SSL management and infrastructure. Table of Contents: What Is OCSP? What Is OCSP Stapling? How OCSP Stapling Works Advantages of OCSP Stapling Limitations of OCSP Stapling Browsers That Support OCSP Stapling How to Verify If Your Server Has OCSP Stapling Enabled How to Enable OCSP Stapling What Is OCSP? In simple terms, OCSP (Online Certificate Status Protocol) is a mechanism that allows your device (whether it’s a mobile or desktop) to check if a digital certificate used by a website is still valid. SSL certificates play a crucial role in securing websites and online transactions by verifying their identity and encrypting data exchanged between user browsers and site servers. However, all trusted SSL certificates come with an expiration date and can be revoked in cases of critical security incidents, rendering them untrustworthy. This is where OCSP comes into play. When you visit a website using HTTPS, your browser automatically checks with the website’s certificate authority (CA) to ascertain if the SSL certificate is still valid. This process occurs in the background, and if the certificate is no longer valid, your browser will display a warning message to alert you about potential security risks. What Is OCSP Stapling? OCSP stapling is a technology designed to enhance the performance and security of the OCSP check performed by web browsers to validate a website’s SSL certificate. With OCSP stapling, the website’s server takes the OCSP response from the certificate authority and “staples” it to the SSL certificate during the SSL handshake process. This stapled response is then transmitted to the browser along with the certificate, eliminating the need for the browser to conduct a separate OCSP check. What Is OCSP Must-Staple? OCSP Must-Staple is a security extension that can be added to an SSL certificate to ensure that the certificate’s status is checked each time a website is visited. When a certificate has OCSP Must-Staple enabled, the website’s server is obligated to provide the client with an OCSP staple whenever it receives an SSL certificate request. If the server cannot obtain a valid response while checking the certificate’s status, the website will not load. This feature serves as a security measure to prevent attackers from using revoked certificates to impersonate websites or intercept sensitive data. How Does OCSP Stapling Differ From CRLs? OCSP stapling and Certificate Revocation Lists (CRLs) both serve the purpose of checking the revocation status of SSL certificates. However, they operate differently within the SSL handshake process. Certificate Revocation Lists (CRLs) are repositories that contain lists of revoked certificates. When a client connects to a server via SSL, the server sends its digital certificate to the client. The client then checks the certificate’s revocation status by downloading the CRL from the certificate issuer’s repository and comparing the certificate’s serial number with the list of revoked certificates. If the certificate is on the CRL, the client will reject the certificate and terminate the handshake. OCSP stapling, on the other hand, is a mechanism that allows the server to provide a signed, time-stamped OCSP (Online Certificate Status Protocol) response along with its digital certificate during the certificate status request. As this response already contains the certificate’s revocation status, the client only needs to check the OCSP responder directly provided by the server, instead of downloading the CRL and verifying the certificate’s status against the list of revoked certificates. Why Does OCSP Stapling Matter? When you access an HTTPS website, your browser checks the status of the SSL certificate to confirm its validity. OCSP plays a critical role in this process. However, relying solely on OCSP without stapling can pose challenges. The Certificate Authority (CA) must respond to numerous OCSP requests in real-time, especially for websites with high traffic. This can be cost-intensive for the CA and can also impact end-users, as multiple OCSP responses can slow down page loading times. With standard OCSP, browsers need to inquire about the certificate from both the web server and the Certificate Authority. OCSP stapling simplifies this process, enhancing efficiency and security. How OCSP Stapling Works As mentioned earlier, when a browser connects to a secure website, it must contact the certificate authority’s OCSP servers to verify the SSL certificate’s validity. This process can introduce latency, as the browser waits for the OCSP server’s response. OCSP stapling improves the OCSP protocol by allowing the web server, rather than the browser, to query the CA regarding the SSL certificate’s status. When the web server contacts the SSL vendor, the CA provides a highly secure digitally time-stamped response. This stapled response is then bound to the SSL certificate during the SSL handshake, making the verification process quicker. Instead of reaching out to the CA, the browser only needs to verify the server’s timestamp, trusting it as a reliable CA. Advantages of OCSP Stapling OCSP stapling provides several advantages, including: Enhanced Security: OCSP stapling prevents security threats that may arise from revoked certificates. The stapled response ensures that the client has the most up-to-date certificate revocation status, reducing the risk of man-in-the-middle attacks and other certificate-based vulnerabilities. Improved Performance: OCSP stapling enhances performance by reducing the latency associated with certificate revocation checks. Instead of the client needing to query the CA’s OCSP server directly, the server can provide a stapled response in the SSL handshake, reducing round trips and expediting connection establishment. Lower Network Traffic: By eliminating the need for the client to contact the CA’s OCSP

When you dive into the world of SSL certificates, one term that you’ll come across, regardless of the certificate’s brand or type, is the SHA-256 algorithm. It’s a ubiquitous specification, often mentioned in a certificate’s details or product information. However, for those not well-versed in technical jargon and cryptographic mathematics, SHA-256 can seem like an enigma. In this article, we aim to demystify this algorithm and shed light on what it is and how it works. Table of Contents: What Is Hashing? What Is the SHA-256 Algorithm? Key Features of the SHA-256 Algorithm Is SHA-256 Secure? How Does SHA-256 Work? What Is SHA-256 Used For? SHA Algorithms History Final Words What Is Hashing? Let’s begin by understanding the concept of hashing. Hashing is a process of converting information into a different value. It takes blocks of data and transforms them into a shorter, fixed-length key or value. This transformation is accomplished through a mathematical function, resulting in a unique and complex series of characters. Hashing serves as a secure and efficient method to verify data integrity. When you hash a piece of data, you can later compare the resulting hash to a known value to confirm that the data hasn’t been tampered with or altered. Hashing is irreversible, meaning you can’t use the hash value to retrieve the original data. This property is invaluable for password storage, where only the hash of a password is stored, enhancing security. What Is the SHA-256 Algorithm? The SHA-256 (Secure Hash Algorithm 256) is a widely used cryptographic algorithm that generates a fixed-length 256-bit (32-byte) hash value. Its primary purpose is to create a unique digital fingerprint of data, such as messages or files. This fingerprint, or hash, is produced by running the input data through a complex mathematical function. Key Features of the SHA-256 Algorithm: Message Length: The length of the plaintext should be less than 264 bits. When installing an SSL certificate, you may select SHA-512 and larger digests, but these require more computational power. Digest Length: The hash digest length is 256 bits. While SHA-512 is more secure, it’s often not recommended due to increased computational demands. Irreversibility: SHA-256, like all hash functions, is irreversible. For every input, there is exactly one output, but not vice versa. Multiple inputs can produce the same output, and the output has a fixed size with no restrictions on input size. Is SHA-256 Secure? While no cryptographic algorithm is entirely immune to attacks, SHA-256 has endured extensive analysis and testing, making it a trusted tool for data security. Its security relies on complex mathematical and bitwise operations that make it extremely challenging to find two different inputs producing the same hash. One potential vulnerability is a collision attack, where two different inputs yield the same hash value. While highly improbable with SHA-256’s 256-bit output, it remains theoretically possible. Such an attack, if successful, could compromise data integrity verification systems relying on SHA-256 hash values. How Does SHA-256 Work? To grasp how SHA-256 functions, let’s look at an example. Imagine you have the message “I love apples” and you apply the SHA-256 hash function to it, resulting in this hash: 40b7df43f24bea395b2c0c3c9d48a3db4db631fa396dd0dd8fe7dc64c9de6f6d Now, add an exclamation mark at the end of the message to make it “I love apples!” and generate a new hash: 1751c183f35ed15c2977e5ae7e439fdca79eeae28527ece6efc1a24e4388096f Notice how a single character alteration drastically changes the hash, while the length remains the same. This property ensures that the hash value conceals the size of the original input. When you send this message to a friend, you provide the hash value and specify the algorithm. Your friend generates the hash on their end, and if it matches, they know the message is genuine. The SHA-256 algorithm follows several steps, including data preprocessing, message expansion, and a message compression function. These steps involve manipulating the input data through logical operations to produce the final 256-bit hash value. What Is SHA-256 Used For? SHA-256 is a fundamental component in various security-related applications: Digital Signature Verification: It plays a crucial role in ensuring the authenticity and integrity of digital signatures, protecting messages and documents from tampering. SSL Handshake: During the SSL handshake, SHA-256 compatibility and functions are essential for establishing secure connections between web browsers and servers. Password Protection: Websites store hashed passwords, enhancing security by preventing exposure of actual user passwords in the event of a security breach. Blockchain Transactions Verification: In blockchain technology, SHA-256 ensures the immutability and integrity of transactions by creating unique hash values for each block. SHA Algorithms History Secure cryptographic hash algorithms, including SHA-256, have a notable history. The National Security Agency (NSA) developed these algorithms and made them available under a royalty-free license. The SHA family includes SHA-0, SHA-1, SHA-2 (which encompasses SHA-256), and the more recent SHA-3. While SHA-1 has vulnerabilities and is being phased out, SHA-256 remains a robust choice for data protection. SHA-3 offers an alternative with a different internal design but has yet to replace SHA-2 in current applications. In conclusion, SHA-256 is a cornerstone of data protection on the web. Although we’ve only scratched the surface of its intricacies, you now have a basic understanding of its purpose and significance. As long as quantum computers capable of cracking complex hash functions remain on the horizon, SHA-256 will continue to be a vital component of encryption and authentication protocols, safeguarding digital data.

Introduction: Domain Control Validation (DCV) is a vital step in securing your online presence with SSL certificates. This guide will walk you through the DCV process, equipping you with the knowledge to successfully navigate it in a variety of ways. Discover the DCV method that best aligns with your expertise and circumstances. Table of Contents: Understanding Domain Control Validation (DCV) Exploring DCV Methods Final Step: Verifying the CAA Record Conclusion What is Domain Control Validation (DCV)? Domain Control Validation, or DCV, is an essential verification process conducted by Certificate Authorities (CAs) to confirm that SSL certificate applicants either own the domain or possess administrative rights over it. This validation step is straightforward, devoid of paperwork, and a prerequisite for SSL certificate issuance. Exploring DCV Methods: To confirm your administrative control over the domain in question, CAs offer three distinct DCV methods, each explained in detail below. 1. Email Validation: Email validation remains the most popular and user-friendly method for SSL certificate validation. In this process, the CA sends an approval email containing a validation code to the WHOIS or domain-based email address associated with your domain. To pass DCV, simply open the email and insert the provided validation code. This automated procedure typically takes less than five minutes, making it an efficient way to obtain a Domain Validation certificate. Please note that only specific domain-based or your contact email addresses from WHOIS are eligible for the DCV email method. If your WHOIS email address is hidden for privacy reasons, or you’re unsure about it, refer to your domain control panel or get in touch with your domain registrar. Alternatively, you can use one of the following pre-approved domain-based email addresses: administrator@yourdomain.com admin@yourdomain.com postmaster@yourdomain.com hostmaster@yourdomain.com Ensure to replace “@yourdomain.com” with your actual domain name. Didn’t receive the validation email? Here’s what you can do: Check your spam and junk folder, as email filters may mistakenly mark the CA’s email as spam. Double-check the accuracy of your email address to ensure there are no typos. Attempt to resend the email. If all else fails, seek support from your SSL provider. Selected an email address that doesn’t exist? No worries; you can resolve this issue by following these steps: Access your hosting dashboard and create the domain-based email address specified for validation. Resend the approval email. Important Note: Effective June 16, 2021, Sectigo no longer accepts WHOIS-based email addresses for Domain Control Validation (DCV). 2. DNS Validation: DNS validation is a more technical approach, requiring the creation of a CNAME record in your domain’s DNS settings. This method hinges on the domain name system (DNS), which serves as the web’s phonebook, translating human-readable domain names into machine-readable IP addresses. When selecting DNS validation, you will receive unique validation record values for your specific order. These values can be found in your SSL vendor account. The CA verifies domain ownership by checking for a DNS TXT record with a specific value. You’ll be provided with this unique value to add to your DNS TXT record, which the CA will then verify. After SSL certificate activation, you must add the predetermined domain record values to your domain registrar, ensuring that your firewall doesn’t block the CA’s validation robot. Here are the steps to follow: Log into your domain registrar account and navigate to your domain’s DNS settings. Create the CNAME record using the domain record value from your vendor account. Set the minimal available TTL (Time to Live) for the record to minimize propagation delays or potential setup errors. Remember to verify your CNAME record using a suitable tool. Check Your CNAME Record Sectigo and GoGetSSL require a CNAME DNS type, which looks like this: _b2013ea8353c9760c0221c49dc3e8ca7.yourwebsite.com CNAME 165b83449f4fdf83021de4e6f6ee795a.4ae75dbefe3r7bb8a1878616d8b5ae4.5r4r46855d28f6903.comodoca.com. DigiCert, Thawte, GeoTrust, and RapidSSL require TXT DNS type, which looks like this: yourwebsite.com TXT “w34f54t4t45t354eer98rn4jf4449nfrf” or dnsauth.yourwebsite.com TXT “w34f54t4t45t354eer98rn4jf4449nfrf”. After setting up the CNAME record, what’s next? Newly added DNS records may take up to 72 hours to propagate globally, although this typically happens within a few hours. If you need your Domain Validation certificate promptly, the other two methods may be more suitable. HTTP/HTTPS Validation: Please note that this method is no longer applicable for validating Wildcard SSL certificates. HTTP/HTTPS validation necessitates the upload of a TXT validation file to your domain’s directory. Ensure that you can access your hosting account via your dashboard or FTP, and that the CA can access it through any web browser. The CA will scan your website, searching for the TXT file at the designated link. Once the CA’s crawler locates the TXT file on your website, your SSL certificate will successfully pass domain validation. To obtain the validation file, access your vendor’s account after selecting the file-based option. The validation file is typically a .txt file with an alphanumeric name (e.g., B4DS4C5H73UFGJDHJ.txt). After downloading the validation file, you must upload it to your hosting server/panel. Place the file in the “.well-known” folder within the “pki-validation” subfolder of your domain’s document root directory. This ensures that the validation file can be accessed via the specified path for validation: http://yourdomain.com/.well-known/pki-validation/B4DS4C5H73UFGJDHJ.txt. 3. Brand Validation: In rare instances, the CA may require manual Domain Validation, known as Brand Validation. This manual check can take up to 48 hours, after which the CA will either approve or reject your order. Common reasons for orders undergoing Brand Validation include: The domain name being blacklisted or having a questionable reputation. Inclusion of stop words such as “online,” “secure,” “payment,” “bank,” and others, which can trigger manual verification. Hidden brand names within domain names, leading to manual scrutiny. Orders originating from restricted countries. Final Step: Check the CAA Record: Starting from September 8th, 2017, all Certificate Authorities (CAs) must adhere to your CAA policy as a security measure. Your CAA record should permit the CA to issue an SSL certificate for your domain. Failure to do so will result in the order being labeled as “Pending” until the record is updated. By default, in the absence of a CAA record, any CA can issue an