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What is a Code Signing Certificate and How Does it Work?

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In a world where technology dominates our lives, building trust is essential. Fortunately, code signing certificates provide us with the security we need to make sure that software can be identified and relied upon as a trustworthy source of information.

But what is a code signing certificate? Read to learn all about code signing certificates and how they work.

What is a Code Signing Certificate?

A Code Signing Certificate is a technology that includes the process of validation for publishers of software, content, code, and scripts based on a digital signature to authenticate their identities to web users. In addition to identifying the identity of the publisher, code signing also protects the code from being tampered with.

By using code signing certificates, software developers can securely attach their digital signatures to applications and programs. This reassuringly informs end-users that the integrity of said content has been maintained since it was originally signed by its developer – guaranteeing a safe experience for all involved.

How to get a Code Signing Certificate?

Code Signing Certificates depend on digital signature technology, which is issued by an internationally trusted third party called Certificate Authority (CA). A Code Signing Certificate from a trusted Certificate Authority (CA) will identify the software and publisher as trustworthy.

Let us understand the process.

Before a software developer can sign their code, they must first generate a public/private key pair. This is typically done using software tools such as OpenSSL, which allows the developer to create a unique key pair.

The developer then submits the public key, along with their organization’s identity information, to a trusted Certificate Authority (CA). The CA verifies the authenticity of the identity information and issues a code signing certificate, which is signed by the CA’s private key.

This certificate contains the developer’s organization’s identity and the developer’s public key. Once the developer has this certificate, they can use it to sign their code, and end-users can use the certificate to verify the authenticity of the code.

When web users download the signed code, they get a copy of the certificate to authenticate the identity of the publisher/author. The web browser verifies the digital signature, and the user trusts that the code did indeed come from that particular developer.

What happens when a Code Signing Certificate is issued:

  • The code is put through a one-way hash function. This creates a “digest” of fixed length.
  • The developer’s private key is used to encrypt this digest.
  • The digest is combined with the certificate and hash algorithm to create a signature block.
  • The signature block is inserted into the portable executable file.

Steps of Authentication Process When Code is Downloaded from Another User:

  • The certificate is examined, and the developer’s public key is obtained from the CA.
  • The digest is then decrypted with the public key.
  • The same hash algorithm that was used to create the digest is run on the code again, to create a second digest.
  • The second digest is compared to the original.

Advantages of using a Code Signing Certificate:

Protects your Code
A digital signature indicates that a piece of code belongs to you and has not been corrupted with malware. Unsigned code presents frightening warning messages in an attempt to limit the chance of malicious code harming a user’s PC, device, or network.

Increases Adoption
Because of the proliferation of malware disguised as legitimate software, customers view any software downloaded from the web with extreme suspicion. Unexpected warning messages from their OS or browser such as those resulting from unsigned code, no matter how benign, cause many users to cancel the installation.

Protects your Reputation
Consumers expect a smooth installation process; warning messages look unprofessional and create suspicion. Code Signing allows you to forgo these types of messages and helps you train your customers to only trust digitally-signed codes.

Meets the Requirements of your Partners
Your partners and distribution channels want to ensure that they are not risking their reputation and their customers’ safety by distributing your code. Digital signatures allow them to verify that the content they are sharing is legitimate.

Simplifies Monitoring and Enforcement
A digital signature using a Code Signing Certificate helps identify the authenticity of the signed code, making it easy to screen for modified files. With a DigiCert Time-stamp, any signed code remains valid even after the certificate expires. The time stamp tells users that they had a valid certificate when the software was signed.


Code signing certificates are a powerful and invaluable cybersecurity asset. With the understanding of their many benefits, it is clear that investing in one should be at the top of your to-do list.

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