What is a trust certificate on iPhone?

Answered by Jeremy Urbaniak

A trusted certificate on an iPhone is a digital certificate that is used to establish a secure and trusted connection between the device and a server or website. It is a crucial component in ensuring the security and authenticity of online communications.

When you connect to a website or server using a secure connection, such as HTTPS, the server presents its digital certificate to your device. This certificate is essentially a cryptographic proof that verifies the identity of the server and ensures that the communication between your device and the server is encrypted and cannot be intercepted or tampered with by malicious entities.

In order for your iPhone to trust the certificate presented by the server, it needs to have a list of trusted root certificates installed. These root certificates are issued by trusted certificate authorities (CAs) and are pre-installed on your device by Apple. They serve as the foundation of trust for all other certificates issued by the CAs.

When your iPhone receives a certificate from a server, it checks if the issuing CA’s root certificate is present in its trusted list. If it is, the certificate is considered trusted and the connection is established. If not, your device may display a warning or error message indicating that the certificate is not trusted.

The trust in a certificate chain is established by a hierarchical structure. At the top of the hierarchy are the root certificates, which are self-signed certificates issued by the CAs themselves. These root certificates are used to sign intermediate certificates, which in turn can be used to sign end-entity certificates, such as those used by websites.

By including the public key of the root certificate in your device’s trusted list, your iPhone can verify the authenticity of any certificate signed by that root. This chain of trust ensures that the certificate presented by a server is issued by a trusted CA and has not been tampered with.

It’s important to note that the trust of a certificate does not guarantee the trustworthiness of the server or website itself. It only ensures that the communication with the server is secure and that the server’s identity has been verified by a trusted CA.

In some cases, you may encounter situations where you need to manually install additional root certificates on your iPhone. This can be necessary when connecting to internal corporate networks or accessing websites that use certificates issued by non-standard CAs. By manually installing these additional root certificates, you can establish trust with these entities and securely connect to them.

To summarize, a trusted certificate on an iPhone is a digital certificate that is used to establish secure and trusted connections between your device and servers or websites. These certificates are issued by trusted CAs and are verified using a chain of trust established by pre-installed root certificates on your device.