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Code Signing Certificate

Everything You Need to Know About Code Signing Certificates

Today, 3rd-parties impersonating software publishers have made it tricky for consumers to navigate the online realm, requiring them to always be wary. Consumers download and install a variety of applications that make their lives easier. However, is there a way to ensure those software/app codes are safe or not? Well, there is, and it’s by using digital security certificates such as code signing. But what is a code signing certificate, and how does code signing work? This article presents an in-depth guide on the code signing certificate, its types, benefits, examples, and many more.

What is Code Signing Certificate

What is a Code Signing Certificate?

The software provider uses a cryptographic hash to ensure and authenticate the software through a process known as code signing. Developers can sign the apps and executable files using the code signing certificate before releasing them to the public.

Software developers are provided with digital signatures, which they need to place onto their code, executable software, and program file. Obtain the signature and certificate to ensure software safety during download and installation without tampering.

Code signing certificate helps browsers and operating systems assess that the software comes directly from the publisher. Furthermore, it helps demonstrate the authenticity and code integrity of the downloaded or installed software. Moreover, users can trust any upgrades of the software coming from the software publisher.

A code signing certificate removes alerts about software from an “unknown publisher,” improving user experience. It ensures the software developer is verified and the application comes from a verified source.

The primary job of the certificate is to verify the author of the content and ensure an unauthorized party does not temper it. Moreover, it ensures that the software signed with a certificate is not malware that any hacker has offered to compromise user data.

Integrating code signing certificates into your software helps boost trust and confidence in users and increase the download rate. A typical code signing certificate includes a signature, company name, timestamp, and other necessary things.

What is the Purpose of Digitally Signing Software Code?

Digitally signing code verifies the authenticity and integrity of the software code. Digitally signing software code allows users to verify the software publisher’s identity & confirm that no one can tamper with the code.

This helps prevent the distribution of malware and other malicious code as legitimate software and protects users from downloading software that contains malicious code.

Verifying the authenticity and integrity of the software code helps establish trust between the software publisher and the user.

There are different types of certificates, such as OV (Organization Validated) and EV (Extended Validation) code signing certificates issued by trusted Certificate Authorities (CA) after a thorough background check of the organization and examination of its business practices and reputation.

How Does Code Signing Work?

The code signing certificate process involves several steps that commence with creating unique key pairs using the public key infrastructure.

How Does Code Signing Work

Let’s have a closer look at how does code signing certificate work:

Public-Private Key Generation

You can generate the public-private keys using the public key infrastructure to encrypt the software code with cryptography. The CA will verify the public key generated and ensure it belongs to the designated software developer. The Private key remains private/secure, and the public key remains public for decryption purposes.

Once the CA verifies the key, it’ll return the same along with the code sign certificate. The CA, here, acts as a trusted entity that assumes the responsibility of generating and signing software with code sign certificates. The certificate generated by them conforms to industry standards and authenticates the trustworthiness of the software developer.

Hash Function

Now, the CA will run your software code through a hashing function, which is a one-way function that turns text content into irreversible arbitrary values. This output of arbitrary values is known as a digest, which is encrypted with a private key and comes in handy when the data is sent to users.

The private key here ensures that everyone can see the content, but no one can tamper with it or insert their own rogue content. After combining the code signing certificate, the hash function, and the digest into a signature block, you can publish the software.

Code Signing Certificate

When users download and install the digitally signed software, their computer system will check for the legitimacy of the code signing certificate. In this step, you use the public key to decrypt the digest.

You also use the hash function again on the software code to match the digest provided by the publisher. If it matches, the user can install the software program without warning.

Root Certificates

Even though code-signing certificates provide assurance of authenticity, there are many malicious actors who can create rogue key pairs and certificates that appear to be valid. Root certificates come in handy to differentiate such rogue certificates from legitimate ones.

You can think of a family where you want to trace the root of the code signing certificate provided to you. The root certificates help determine if the code signing certificate in that tree is trustworthy using the chain of trust. The chain of trust allows validation of the original signing authority of the code signing certificate.

Types of Code Signing Certificates

There are basically two types of code signing certificates offered by most CAs and distributors: Organization Validation or Individual Code Signing and Extended Validation certificates. Let’s get to know more about them:

Organization Validation Code Signing Certificate

The Certificate Authority uses Organization Validation or Individual Validation certificates to validate small businesses or individual software publishers. The CA will verify whether the organization has legal registration and up-to-date records.

The CA would evaluate your organization using online government data and the official website to determine your registration status. The information in the government records must match the information you submitted in order for the CAs to issue a code signing certificate.

This is essential because the name of the company or individual who applied to a CA will appear on the certificate.

Here are some reasons why choose the OV code signing certificate:

  • Instant Removal of Warnings: Since the certificate will include your organization’s name, it’ll help eliminate the unknown publisher warnings.
  • Unlimited Signing: You can digitally sign as many software and executables as you like until your OV code signing certificate is valid and in effect.
  • Software Timestamping: The certificate allows you to timestamp your digital signature to ensure that it’s valid and recognized even when the certificate’s validity has expired.
  • Compatibility: The certificate is compatible with most platforms, such as Adobe, Java, JAR, Windows, and mobile apps.

Extended Validation Code Signing Certificate

Software publishers can receive the greatest degree of trust with EV code signing certificates. During installation, applications certified with such certificates can easily bypass SmartScreen filters on Windows and mobile devices. However, obtaining such a certificate requires going through a religious authentication and validation process.

Here, the CA will ask for certain types of specific documents to prove your business’s legitimacy. Once you submit all the necessary documents, the CA will take 1 to 5 days for validation and issue the certificate. But once you acquire the same, it removes unknown publisher warnings and boosts users’ trust in your brand.

EV code signing enables the easy detection of updates made to executable files. Furthermore, the certificate’s timestamping characteristics can alert users whether or not the software has a valid certificate.

Here are some more reasons to choose an EV code signing certificate:

  • Two-Factor Authentication: In EV code signing, the CA sends the publisher the private keys and an encryption token stored in secure hardware such as a USB drive.
  • Automatic Reputation and SmartScreen Filter: Software programs signed with EV certificates get instant recognition with the SmartScreen filter and a verified publisher badge at installation.
  • Time-Sensitive Signing: EV code signing certificates have timestamping ability to ensure that your digital signature lives on even after the certificate expires.
  • Universal Compatibility: EV code signing certificates have universal platform compatibility, as you can sign software for almost all platforms.
  • Support for Hardware Security Module (HSM): EV certificates support hardware security modules to give you more control over certificate credentials.

Benefits of Code Signing Certificate

Code signing is important for several reasons, such as verifying publisher identity with extensive vetting. It allows for cross-verification of the software code to ensure no one can modify it.

Software signed with digital certificates also ensures its code is exactly the same as before signing. That said, here are several other benefits of a code sign certificate, as discussed below:

  • Code signing presents a way to secure your software, application, and executable files digitally.
  • It extensively vets the organizations for their authenticity and integrity before the CA can issue the certificate.
  • The hash function ensures the software code maintains its integrity.
  • Code signing certificates include timestamping features that ensure your digital signature remains valid even after the expiration of the certificate.
  • Code-signed applications can easily pass the SmartScreen filter to gain reputation and verified publisher badge to inform users it’s coming from an authorized source.
  • It helps eliminate the risk of code tampering and malicious code insertion.
  • Boosts trust and confidence in users to download, install, and use your software programs.

Code Signing Examples

Have you encountered those dialogue boxes that ask, “Do you want to allow this app to make changes to your device?” when you try to run a program? If yes, then you have seen the code signing in action.

If you sign software or applications with a digital security certificate such as OV or EV, the Windows OS will display the following message:

Verified Publisher

However, if you don’t sign the software using a code signing certificate issued from a renowned CA or their trusted distributors, the warning message will look something like this:

Unverified Publisher

Some of the best examples of code-signed software include:

  • Windows Applications
  • Windows Software Updates
  • Apple Software
  • Microsoft Office
  • Adobe Software
  • And other

What Does Code Signing Do?

Code signing helps prove two things: code/content source legitimacy and code/content integrity. Let’s get to know more about each aspect:

Code/Content Source Legitimacy

The first thing code signing does is it verifies that the software or application is coming from an authoritative source, for instance, a developer or a publisher. When a user downloads software from the internet, browsers may show an alert that there are dangers in downloading this data.

The software may show an “unknown publisher” warning, but you can eliminate this warning by acquiring a code signing certificate from a renowned Certificate Authority or their trusted distributor. Signing your software helps identify the publisher’s name on the certificate.

Code/Content Integrity

Code signing is further used to verify the piece of code or content included in the software is not tampered with. It checks whether the content provided fits its designated purpose or not. If the code or the content is found modified or altered from its original state after digital signing, the signature will become invalid.

Thus, whenever a user tries to download or install such types of software, the system will display the “unknown publisher” warnings. Signing code is advantageous for consumers and developers since it increases users’ confidence in the source.

The Importance/Strengths of Code Signing

Code signing is an important security measure that helps to establish trust between software publishers and users. Here are some of the key strengths of code signing:

  • Identity verification: Code signing allows software publishers to digitally sign their code using a private key associated with a code signing certificate, which helps users verify the software publisher’s identity.
  • Tamper detection: Code signing helps ensure that the code has not been modified since it was signed. This helps prevent malware and other malicious code from being distributed with legitimate software.
  • Protection against malware: Code signing protects users from downloading and installing software tampered with or modified by an attacker.
  • Compliance: Many industries and government agencies are now strict about digitally signing the software/application code before using it.
  • Brand Protection: With code signing, software publishers can protect their brands from being victims of any malware attack.
  • Improve User Experience: By providing trust and security, code signing can enhance the user experience by increasing confidence in the software and reducing the risk of malware infections and other security issues.
  • Reducing warnings and error messages: Software signed with a valid code signing certificate won’t generate any warnings or alerts when installed on a user’s computer, making the user experience smoother and more pleasant.

Weaknesses of Code Signing

  • Relying on the certificate authority’s trust: Code signing relies on the trust of the CA that issues the certificate. If a CA’s private key is compromised, it can be used to issue fraudulent certificates and sign malicious code.
  • Private key compromise: If the private key provided to publishers gets compromised, attackers can use it to sign malicious code, which will be distributed as legitimate software.
  • Malware can evade detection: Some forms of malware can evade detection by code-signing scanners and antivirus software.
  • The only proof of authenticity: Code signing only provides proof of authenticity; it does not ensure the software is free of vulnerabilities or malware.
  • Complexity: Setting up and managing a code-signing infrastructure can be complex and time-consuming, particularly for organizations that must sign code for multiple platforms.

Steps for End-Users to Determine Software Authenticity

  • Check the software you are planning to download and install comes from an authority publisher i.e., Microsoft.
  • Check the software name you are planning to download or install. For example, check the MS Office software name.
  • Check the publisher name of the software and validate it’s the same who wrote the software. Doing so can be difficult as the software download site differs from the publisher’s.
  • Inspect the code signing certificate attached to the software and validate the publisher’s name.
  • Lastly, check if the renowned and publicly trusted CA has issued the certificate.

Where is Code Signing Used?

The code signing certificate is supported and compatible with most platforms except for Linux. Linux-based software is not signed and may come as unsigned, which will show an “unknown publisher” warning.

Apart from that, here are some types of software where code signing is used:

  • iOS Apps: Code signing in iOS apps is done through Xcode, which lets the OS know who signed the app and ensures it hasn’t been altered.
  • C#: Visual C# gets a unique name sign code unavailable anywhere else and can’t be spoofed.
  • Windows Certificate: Any executable or software program can be signed with a Windows certificate to verify its security and integrity. A trusted Certificate Authority must sign software for it to be secure.
  • Visual Studio: It’s helpful in strong name signing for assemblies, which allows other computer systems to trust the software’s developer.

Apart from these, code signing is used anywhere to authentic the source of the software, including the following:

  • Window applications
  • Software updates and patches
  • Apple software
  • Microsoft Office objects and macros
  • Java software
  • .jar files
  • All other types of executable

How do Verify the Software is Signed with a Code Signing Certificate?

When you have a signed executable or software with a code signing certificate, the signing technology creates a layer of protection. This layer protects it from any alterations or modifications hackers may try.

Thus, when your users try to download these files, the browsers will let them do so without any interruptions or alert messages. When a user tries to download unsigned software, the browser or the OS system may show an alert such as below:

Unverified Publisher

When you encounter such warnings, it means the software you are trying to download or install isn’t coming from a verified source. Thus, you should abandon the download and installation and look for the authorized source.

How Does Timestamping Work with a Code Signing Certificate?

How Does Timestamping Work

Timestamping is a feature that can be used with a code signing certificate to ensure that a digital signature remains valid even after the certificate expires.

When a code signing certificate is used to sign software, the signature includes the current date and time. If the certificate expires after the software is signed, the signature is no longer considered valid, and some systems may treat the software as untrusted.

Timestamping solves this problem by adding a timestamp to the signature. The timestamp is created by a trusted third-party timestamp authority (TSA) and records the date and time the signature was created.

When a user installs the software, the system verifies the timestamp to confirm that the signature was created prior to the certificate expiration date. If the timestamp indicates that the signature was created before the certificate expired, the system accepts the signature as valid, even if the certificate has already expired.

Timestamping helps keep the signature valid and ensures that the software hasn’t been tampered with after signing.

It is important to note that timestamping is not the same as renewing a certificate. Timestamping only verifies the signature’s authenticity but does not extend the certificate’s validity period. One must obtain a new code-signing certificate to sign new software or software updates after the certificate has expired.

See Also: Best Practices for Code Signing Time Stamping

What’s After My Code Signing Certificate Expires?

If your code signing certificate has expired, you can renew it from your certificate authority and install it again on your software. Most certificates have a typical validity period of two years, after which you have to renew the same.

However, since most code signing certificates come with the time-stamping feature, your certificate still remains valid indefinitely even after expiry. Additionally, you can provide your CA with your email ID to get regular updates about your certificate expiry so that you can renew it timely.

Best Practices to Follow for Code Signing Certificate Security

For the safety of your software and code signing certificate, here are some best practices everyone should follow:

  • Access Control: Limit the access to private keys of your certificate to only authorized personnel. Doing so restricts its exposure; otherwise, hackers can access and use it to distribute the malicious code to your users.
  • Certificate for Test Signing: Developers should use either self-signed or a certificate from a private CA for software in pre-release to test it in a secure environment.
  • Use High-Security Standards: Use a high-standard security module or vault to secure your certificate keys from hackers. It should meet the FIPS-140 level 2 certificate for protection.
  • Scan for Malware: Run a malware scan before signing your software code because code signing will authenticate your code but not what’s inside it. Thus, be careful and execute the necessary virus and malware scans on software code.

What is the Difference Between Public Code Signing and Private Code Signing?

Public code signing and private code signing are two different methods of code signing.

Public Code Signing is the process of signing code with a certificate issued by a trusted third-party certificate authority (CA). Most systems and browsers widely recognize and trust these certificates. Software developers and publishers typically use public code signing certificates to distribute their software to a wide audience.

On the other hand, Private Code Signing is the process of signing a code with a certificate issued by an internal certificate authority (CA) within an organization. These certificates are not recognized by most systems and browsers and are usually utilized to sign code that will be distributed solely within an organization.

The main difference between public and private code signing is the trust and recognition associated with the certificate. Public code signing certificates are widely recognized and trusted, while private code signing certificates are only recognized and trusted within the organization that issued them. Another difference is the level of validation and verification that is required to obtain a certificate. Public code signing certificates typically require a more extensive validation and verification process than private code signing. This is because public software is meant to be used by a large audience and therefore needs more security.

What is the Difference Between Regular Code Signing and EV Code Signing?

OV and EV code signing are two types of code-signing certificates used to sign software and executable files digitally. The certificate’s associated level of trust is one of the key differences between regular code signing and EV code signing.

EV code signing certificates undergo a more rigorous validation process, making them considered more trustworthy and secure. Additionally, the EV code signing certificate also has the benefit of showing the organization’s name in the browser’s address bar, which helps build the organization’s reputation.

EV certificates are compatible with Microsoft SmartScreen, which warns users if an application is from an untrusted source. OV code signing certificate does not offer this feature.

Final Thoughts

Code signing binds the identity of the publisher with the code for users to know that it’s coming from a verified source. It offers a way for developers to securely provide their software or applications under their name over the internet without fearing malicious activities.

The publisher typically requests a code signing certificate from a Certificate Authority, who then issues the certificate. You can request and purchase the same from renowned CAs such as Comodo or Sectigo. Additionally, you can buy the same certificate at affordable and cheap prices from trusted distributors or resellers.

Frequently Asked Questions

What does code signing mean?

A Certificate Authority verifies that the content or code of software or applications has not been modified or tampered with since it was signed in code signing. Doing so helps users download and install the software only from verified sources.

What is code signing in cryptography?

Cryptography encrypts the public and private keys used in code-signing software, thereby verifying the identity of the software provider and ensuring that the software remains unaltered after signing.

Who uses code signing?

Code signing is necessary for all the software developers, programmers, and engineers, who build applications for Microsoft, iMac, Android, iOS, and other platforms.

Is code signing required?

Yes, code signing the software or application is mandatory if you’ve developed software for Microsoft, Google, or Apple platforms.

What do you need to obtain a code signing certificate?

Code signing certificate generation requires the following three steps: 1. Generating CSR, 2. Completing the validation process by providing necessary documents, and 3. Downloading the certificate.

Who issues code signing certificates?

Code Signing Certificate providers or Authorized organizations known as Certificate Authorities, such as Comodo, Sectigo, and others, issue code-signing certificates which are crucial for software signing.

What is IV code signing?

IV or Individual Validation is simply the OV code signing certificate allotted only to independent software developers. The certificate has the same features and offers the same benefits as the OV code signing certificate.

Do code signing certificates expire?

Yes, all code signing certificates have an expiry period that ranges from a few months to two years. Once the certificate expires, you must renew the same from your CA. However, most certificates have a timestamping feature that enables your digital signature to remain valid even after the certificate expires.

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