Introduction
A digital certificate is a tool that we use to determine a cryptographic link between a public key and its owner. We also call it a public key certificate. We are using them to share the public key for authentication and encryption purposes. A digital certificate has many components such as a certified public key. Organizations use them to recognize data about the owner of the public key concerned metadata of them, and a digital signature of the public key that was created by the certificate-issuing authority.
The primary purposes of PKI (Public Key Infrastructure) are validation, administration, and revocation of digital certificate security. Public Key Infrastructure is a system through which we distribute and validate public keys. Public key cryptography mainly depends on a pair of keys. A private key and a public key. The private key stays with the owner of the digital certificate for signing and decryption purposes. The certificate authority shares the public key with the receiver of the data; we can use a public key for encryption and validation of the signed data of the certificate owner. The digital certificate security helps you share the public key in such a way that it can be validated.
We use digital certificates in cryptography functions of a public key. These certificates are necessary for initiating a secure connection between a web user and a web server. We can also use these certificates for sharing keys that we use for encryption of the public key and validation of digital signatures. All the major browsers and servers use these certificates to assure the authenticity of the content. A digital certificate makes sure that the data is not edited by some hacker. Another purpose of using these is the encryption and decryption of the data.
Who can issue a digital certificate
Several certificate issuing authorities are responsible for the issuance of different types of digital certificates. Certificate issuing authorities are a trustworthy third party in the circumstances of a Public Key Infrastructure. By opting for a certificate issuing authority, users are trusting its digital certificate security.
It is also possible for an individual to create his Public Key Infrastructure and issue himself a digital certificate. It is a good approach if you are planning to use it only for internal use. Still, the majority of the digital certificates belong to certificate issuing authorities.
Difference between a digital certificate and a digital signature
By using public-key cryptography, we can perform several useful functions such as validation and encoding. Another function that we can perform with it is a digital signature. A digital signature is a component that we can generate by using different codes to sign the particular data. It is a piece of irrefutable evidence that the data has the signature of the owner of a specific public key.
We generate a digital signature with the help of hashing of the data which we want to sign by one-way cryptographic hash. The result of this process is then encrypted by using the private key of the signer of data. This digital signature includes the hash, which we can only validate with the help of the public key of the sender for decryption of the digital signature. For this purpose, we have to go through the same process of a one-way hashing algorithm on the same data.
After this process, we will be able to compare these two hashes. The matching of these two hashes will prove that the data is the same as it was at the time of signing and the data was sent by the public key pair holder who signs it. If they do not match, it means that the data was compromised. Generally, a digital signature is dependent on the transmission of the public key in the form of a digital certificate. We need to digitally sign a digital certificate, and we can not trust it unless we verify the signature.
Types of Digital Certificates
Whenever we talk about digital certificates, the majority of us only mention SSL/TLS certificates as digital certificates. No doubt, SSL/TLS are the most widely used digital certificates, but there are two other types of digital certificates as well. These types are code signing digital certificates and user/client certificates, and these are also important for securing our online communication. In the following paragraph, we will discuss these three types of digital certificates. These are very important in digital certificate security.
SSL/TLS Certificates
SSL/TLS certificates are a very popular tool to secure communication over the open internet. These certificates ensure that the website is secure. We use asymmetric encryption for these certificates. As we know, in asymmetric encryption we use two different keys for encryption and decryption. Basically, an SSL/TLS certificate is a data file installed on the server of a website. Websites use an SSL/TLS certificate for securing the data of their users.
An SSL/TLS certificate is very important to win the trust of the users. These certificates not only secure the data but also validate the ownership of the website and keep the hackers away. SSL/TLS certificates also ensure that the user is interacting with the right server which is the owner of that domain. All these things make a website secure from different types of online attacks.
Code-Signing Certificates
Another important type of digital certificate is a code signing certificate. We use these certificates to guarantee the authenticity of the code that we use for coding software. Code signing SSL verifies the developer of software and also proves that the code is safe and has not been tempered. Just like SSL certificates, these certificates also use a pair of private and public keys.
The developer uses the private key for signing the code and the user uses the public key to confirm the developer’s identity. It confirms that the software belongs to a trusted source. A code signing certificate comes with the timestamp. Timestamping makes sure that the code remains valid even after the expiry of a digital certificate.
User/Client Certificates
Unlike the SSL certificates, a user/client certificate verifies the people and devices which are requesting to access the data. These are like passwords but you do not need to memorize them and they are more secure as compared to a password. A user/client certificate uses the Public Key Infrastructure for verification purposes. As we have discussed earlier, these certificates are different and can not encrypt data. These certificates make sure that only desired people can access the data.