A Comprehensive Guide to X.509 Certificate

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X.509 Certificate: What is it, How Does it Work, Its Usage and Applications & Where to Buy it!

Cyber security is the topmost concern for network security professionals in today’s time. With advancing technologies, hackers and cyber attackers are now more capable of strategizing cyber attacks to steal information and harm organizations.

Hence, to prevent organizations and internet users from such attacks, security certificates like X.509, SSL, TLS, code signing, are issued by the certification authorities. These certificates ensure that your browsing experience stays secure and no external malicious files harm your system.

This blog is specifically dedicated to the X.509 Certificate. We will explore all the aspects of the X.509 certificate and will disclose how adding this certificate to your browser can add to a safe internet browsing experience.

What Is an X.509 Certificate?

X.509 is a widely accepted international public key infrastructure (PKI) that securely associates cryptographic key pairs with identities like individuals, organizations, and websites.

It is a certificate-based authentication that facilitates the secure transfer of information by leveraging digital signatures. The X.509 standard is used to verify that a public key belongs to a particular user or organization.

The X.509 certificate can be obtained from a trusted CA (Certification Authority) and can be used to provide security to your programs or internet browsers.

The X.509 certificates are widely used in multiple internet protocols such as TLS/SSL, HTTPS, etc. They generally help manage security and identity in computer networking and the internet.

What is Inside an X.509 Certificate?

An X.509 certificate contains the details of its owner and the certification authority issuing it. Here is what’s inside a standard X.509 certificate:

1. Version Number

It indicates the X.509 version that applies to the certificate through which the system knows what data to include in the certificate.

2. Serial Number

The Certification Authority that issues the certificate assigns a unique serial number to the certificate to distinguish it from other certificates.

3. Signature Algorithm Identifier

It consists of details of the algorithm which is used to sign the X.509 certificate.

4. Issuer Name

It provides details of the certification authority that created and issued the certificate.

5. Validity Period

Every security certificate comes with an expiration date. Hence, this field denotes the period for which the X.509 certificate is valid.

6. Subject Name

This field mentions the name of the user to whom the certificate is issued.

7. Subject Public Key Information

The certificate has a separate field allocated to define the subject’s public key used with the algorithm identifier to conduct its functioning.

8. Signature

It consists of the hash code for all fields generally encrypted by the certification authority’s private key.

9. Extension Block

These are optional fields that contain their own unique IDs and are expressed as object identifiers with a defined set value.

How Does X.509 Certificate Work?

The X.509 certificate or the X.509 standard is based on Abstract Syntax Notation One (ASN.1), which is an interface description language.

ASN.1 defines different data structures that could be serialized & deserialized in a cross-platform way.

The X.509 certificate consists of identity, and a public key bounded together with a digital signature or a hash function.

The X.509 certificate format leverages a related public and private key pair for encrypting and decrypting a message being transferred from one point to another.

It might sound a little confusing, so to put it in layman’s language, X.509 certificate works as an identity card that is required during the authentication process of a website, file, or any other program.

What are the Formats of an X.509 Authentication Service Certificate?

Now that it has been explained what is an x.509 certificate, we must also understand its different formats. Here are the two common formats an X.509 certificate uses:

1. Binary

The X.509 certificate can be encoded in a binary format using these two methods:

 icon-angle-right .DER (Distinguished Encoding Rules)

It is a platform-independent format that uses a single binary certificate and is the default format for most internet browsers. It is commonly used for certificate requests that are usually DER-encoded and later base64-encoded.

 icon-angle-right PKCS#12 (Public-Key Cryptographic Standards)

It is a password-encrypted one or more certificates packed together by a certification authority that consists of the user’s private key.

2. Base64 (ASCII)

The X.509 certificate can be encoded with Base64 format using the following ways:

 icon-angle-right .PEM

It is the default format for OpenSSL, which is suitable for transferring files as text between systems. These are mostly used while making a certificate request in an email.

 icon-angle-right PKCS#7

It is a format used when packaging one or more certificates together that are not encrypted or signed. This certificate format is used to deliver various certificates together to a destination.

What is X.509 Certificate Used for?

An X.509 certificate has multiple uses and can be used for the following:

1. To Enable the Functioning of TLS/SSL Certificates

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are the foundation of HTTPS secure browser connections. Without an SSL/TLS certificate, hackers can effortlessly access a network and modify it to their use.

However, the functioning of the SSL/TLS is based on PKI (Public Key Infrastructure) that is carried out through an X.509 certificate.

2. Document Signing and Digital Signatures

Another prevalent use of the X.509 certificate is digitally signing software, programs, and documents. Digital signature leverages PKI to authenticate the signer’s identity and the signature’s integrity.

Digital signatures are created using a hash function that makes them secure and free from duplication. X.509 standard and its PKI mechanism are generally used to conduct this process.

3. Code Signing Certificate

A code signing certificate is another way to digitally sign the code for your software, programs, and executables. It assures the users that the software is safe and its code has not been tampered with.

X.509 is also used in this process to authenticate the developer with its private key and ensure the right code signing procedure.

4. SSH Keys

SSH protocol is mostly used for communication in cloud services, file transfer tools, network environments, and configuration of management tools. The organizations associated with these processes use SSH keys to authenticate the identity of users accessing the system and processes.

SSH keys are nothing but a form of X.509 certificate that facilitates SSH protocol with a secure access credential to maintain higher security.

5. Digital Identities

X.509 certificate also aids in effective digital identity authentication. In today’s data-driven societies, the X.509 infrastructure enables different digital entities to authenticate people seamlessly and provide improved security for organizations’ workflows.

What are the Key Benefits of X.509 Certificates?

The two primary benefits that you obtain with an X.509 certificate are

1. Enhanced Trust

X.509 certificates are used everywhere, from websites to applications to endpoint devices. They establish a level of trust among users as they are validated and approved by a trusted certification authority.

The users feel confident scrolling through webpages and software that are X.509 certified, as the chances of them bringing in malware are negligible.

2. Higher Scalability

X.509 certificates provide extremely high scalability to secure billions of messages simultaneously.

As the X.509 framework leverages a public key infrastructure, this means the public keys can be openly distributed over the net, and only authorized users can access the network or files through their private keys.

How are X.509 Certificates Issued or Implemented?

The X.509 certificate can only be issued by a certification authority that has its own public key infrastructure. As the X.509 certificate is entirely based on the PKI, the authority must have its own PKI.

Public Key Infrastructure consists of several crucial components, such as:

  • Certificate Authorities
  • Certificate Stores
  • Public-Private Key Pairs
  • Certificate Revocation Lists (CRL)
  • Hardware Security Module

Hence, an X.509 certificate can be purchased from a certified authority for your intended use.

Revoking an X.509 Certificate

Authentication methods are always designed with some flexibility and are never rigid. That is why every security certificate has a validity period.

This is so because if you have an absolute certificate and any user having its rights goes rogue, it can seriously harm the organizational security.

For instance, you purchased an X.509 certificate and installed it on your systems, and gave its access to an employee.

Later the employee had a fallout with the company administration, and he decides to harm the company files by misusing his certificate access rights.

In such a case, the X.509 certificate can be revoked and added to CRL (Certificate Revocation List). Once the certificate is in CRL, it will be considered not valid for authentication.

Key Things to Know for the Right Management of X.509 Certificates?

The following is the process of the X.509 certificate explained entirely from its purchase to its governance:

1. Finding and Purchasing the Certificate

Foremostly, enterprises and individuals who wish to buy the X.509 certificate must conduct a survey and identify their requirements for the certificate.

Once they have enlisted their requirements, they must explore different stores to purchase the X.509 certificate.

2. Issuance and Installation

A Certification Authority issues the X.509 certificate after validating your organization’s details. The issuance process consists of 8-10 individual steps that need to be carefully completed to submit your certificate signing request (CSR).

Once you have received the actual certificate, you must properly configure and install it to the intended programs and software.

3. Renewal of the Certificate

Every security certificate that you buy comes with a specified expiration date. It ensures that the organization is still valid and not taken over by a fraudulent successor. Hence, once your X.509 certificate expires, make sure to renew it in time to avail of its benefits.

4. Governing the Certificate Access

Governing the use of security certificates is vital for organizations. Hence, every enterprise must audit its certificate inventory regularly to check the validity of the X.509 certificate and ensure no unauthorized usage of the certificate.

Wrapping Up

Now that you have a better understanding of what is an X.509 digital certificate and what it is used for, you can check your requirements and be certain of what kind of certificate you need.

About the Author!

Anna Shipman is a Cyber Security Consultant at SignMyCode with a strong technical background and experience with a high analytical skillset. She has been involved in the information security industry for more than a decade. In her free time, we find her helping small and medium businesses strengthen their information security infrastructure.

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